1
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Liu D, Wang B, Vasenko AS, Prezhdo OV. Decoherence ensures convergence of non-adiabatic molecular dynamics with number of states. J Chem Phys 2024; 161:064104. [PMID: 39120030 DOI: 10.1063/5.0222557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2024] [Accepted: 07/24/2024] [Indexed: 08/10/2024] Open
Abstract
Non-adiabatic (NA) molecular dynamics (MD) is a powerful approach for studying far-from-equilibrium quantum dynamics in photophysical and photochemical systems. Most NA-MD methods are developed and tested with few-state models, and their validity with complex systems involving many states is not well studied. By modeling intraband equilibration and interband recombination of charge carriers in MoS2, we investigate the convergence of three popular NA-MD algorithms, fewest switches surface hopping (FSSH), global flux surface hopping (GFSH), and decoherence induced surface hopping (DISH) with the number of states. Only the standard DISH algorithm converges with the number of states and produces Boltzmann equilibrium. Unitary propagation of the wave function in FSSH and GFSH violates the Boltzmann distribution, leads to internal inconsistency between time-dependent Schrödinger equation state populations and trajectory counts, and produces non-convergent results. Introducing decoherence in FSSH and GFSH by collapsing the wave function fixes these problems. The simplified version of DISH that omits projecting out the occupied state and is applicable to few-state systems also causes problems when the number of states is increased. We discuss the algorithmic application of wave function collapse and Boltzmann detailed balance and provide detailed FSSH, GFSH, and DISH flow charts. The use of convergent NA-MD methods is highly important for modeling complicated quantum processes involving multiple states. Our findings provide the basis for investigating quantum dynamics in realistic complex systems.
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Affiliation(s)
| | - Bipeng Wang
- Department of Chemical Engineering, University of Southern California, Los Angeles, California 90089, USA
| | - Andrey S Vasenko
- HSE University, 101000 Moscow, Russia
- Donostia International Physics Center (DIPC), 20018 San Sebastián-Donostia, Euskadi, Spain
| | - Oleg V Prezhdo
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089, USA
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2
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Ma X, Fang WH, Long R, Prezhdo OV. Compression of Organic Molecules Coupled with Hydrogen Bonding Extends the Charge Carrier Lifetime in BA 2SnI 4. J Am Chem Soc 2024; 146:16314-16323. [PMID: 38812460 DOI: 10.1021/jacs.4c05191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2024]
Abstract
Two-dimensional (2D) metal halide perovskites, such as BA2SnI4 (BA═CH3(CH2)3NH3), exhibit an enhanced charge carrier lifetime in experiments under strain. Experiments suggest that significant compression of the BA molecule, rather than of the inorganic lattice, contributes to this enhancement. To elucidate the underlying physical mechanism, we apply a moderate compressive strain to the entire system and subsequently introduce significant compression to the BA molecules. We then perform ab initio nonadiabatic molecular dynamics simulations of nonradiative electron-hole recombination. We observe that the overall lattice compression reduces atomic motions and decreases nonadiabatic coupling, thereby delaying electron-hole recombination. Additionally, compression of the BA molecules enhances hydrogen bonding between the BA molecules and iodine atoms, which lengthens the Sn-I bonds, distorts the [SnI6]4- octahedra, and suppresses atomic motions further, thus reducing nonadiabatic coupling. Also, the elongated Sn-I bonds and weakened antibonding interactions increase the band gap. Altogether, the compression delays the nonradiative electron-hole recombination by more than a factor of 3. Our simulations provide new and valuable physical insights into how compressive strain, accommodated primarily by the organic ligands, positively influences the optoelectronic properties of 2D layered halide perovskites, offering a promising pathway for further performance improvements.
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Affiliation(s)
- Xinbo Ma
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, P. R. China
| | - Wei-Hai Fang
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, P. R. China
| | - Run Long
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, P. R. China
| | - Oleg V Prezhdo
- University of Southern California, Los Angeles, California 90007, United States
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3
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Agrawal S, Wang B, Wu Y, Casanova D, Prezhdo OV. Photocatalytic activity of dual defect modified graphitic carbon nitride is robust to tautomerism: machine learning assisted ab initio quantum dynamics. NANOSCALE 2024. [PMID: 38623607 DOI: 10.1039/d4nr00606b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
Two-dimensional graphitic carbon nitride (GCN) is a popular metal-free polymer for sustainable energy applications due to its unique structure and semiconductor properties. Dopants and defects are used to tune GCN, and dual defect modified GCN exhibits superior properties and enhanced photocatalytic efficiency in comparison to pristine or single defect GCN. We employ a multistep approach combining time-dependent density functional theory and nonadiabatic molecular dynamics (NAMD) with machine learning (ML) to investigate coupled structural and electronic dynamics in GCN over a nanosecond timescale, comparable to and exceeding the lifetimes of photo-generated charge carriers and photocatalytic events. Although frequent hydrogen hopping transitions occur among four tautomeric structures, the electron-hole separation and recombination processes are only weakly sensitive to the tautomerism. The charge separated state survives for about 10 ps, sufficiently long to enable photocatalysis. The employed ML-NAMD methodology provides insights into rare events that can influence excited state dynamics in the condensed phase and nanoscale materials and extends NAMD simulations from pico- to nanoseconds. The ab initio quantum dynamics simulation provides a detailed atomistic mechanism of photoinduced evolution of charge carriers in GCN and rationalizes how GCN remains photo-catalytically active despite its multiple isomeric and tautomeric forms.
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Affiliation(s)
- Sraddha Agrawal
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA.
| | - Bipeng Wang
- Department of Chemical Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - Yifan Wu
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA.
| | - David Casanova
- Donostia International Physics Center (DIPC), 20018 Donostia, Euskadi, Spain
- IKERBASQUE, Basque Foundation for Science, 48009 Bilbao, Euskadi, Spain
| | - Oleg V Prezhdo
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA.
- Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089, USA
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4
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Dai D, Agrawal S, Prezhdo OV, Long R. Impact of large A-site cations on electron-vibrational interactions in 2D halide perovskites: Ab initio quantum dynamics. J Chem Phys 2024; 160:114704. [PMID: 38506296 DOI: 10.1063/5.0202251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 03/03/2024] [Indexed: 03/21/2024] Open
Abstract
Using ab initio nonadiabatic molecular dynamics, we study the effect of large A-site cations on nonradiative electron-hole recombination in two-dimensional Ruddlesden-Popper perovskites HA2APb2I7, HA = n-hexylammonium, A = methylammonium (MA), or guanidinium (GA). The steric hindrance created by large GA cations distorts and stiffens the inorganic Pb-I lattice, reduces thermal structural fluctuations, and maintains the delocalization of electrons and holes at ambient and elevated temperatures. The delocalized charges interact more strongly in the GA system than in the MA system, and the charge recombination is accelerated. In contrast, replacement of only some MA cations with GA enhances disorder and increases charge lifetime, as seen in three-dimensional perovskites. This study highlights the key influence of structural fluctuations and disorder on the properties of charge carriers in metal halide perovskites, providing guidance for tuning materials' optoelectronic performance.
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Affiliation(s)
- Dandan Dai
- College of Chemistry, Key Laboratory of Theoretical and Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Sraddha Agrawal
- Department of Chemistry, University of Southern California, Los Angeles, California 90007, USA
| | - Oleg V Prezhdo
- Department of Chemistry, University of Southern California, Los Angeles, California 90007, USA
| | - Run Long
- College of Chemistry, Key Laboratory of Theoretical and Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, People's Republic of China
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5
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Agrawal S, Casanova D, Trivedi DJ, Prezhdo OV. Enhanced Charge Separation in Single Atom Cobalt Based Graphitic Carbon Nitride: Time Domain Ab Initio Analysis. J Phys Chem Lett 2024; 15:2202-2208. [PMID: 38373150 PMCID: PMC10910588 DOI: 10.1021/acs.jpclett.3c03621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 02/07/2024] [Accepted: 02/14/2024] [Indexed: 02/21/2024]
Abstract
In recent years, single atom catalysts have been at the forefront of energy conversion research, particularly in the field of catalysis. Carbon nitrides offer great potential as hosts for stabilizing metal atoms due to their unique electronic structure. We use ab initio nonadiabatic molecular dynamics to study photoexcitation dynamics in single atom cobalt based graphitic carbon nitride. The results elucidate the positive effect of the doped cobalt atom on the electronic structure of GCN. Cobalt doping produces filled midgap states that serve as oxidation centers, advantageous for various redox reactions. The presence of midgap states enables the harvesting of longer wavelength photons, thereby extending the absorption range of solar light. Although doping accelerates charge relaxation overall, charge recombination is significantly slower than charge separation, creating beneficial conditions for catalysis applications. The simulations reveal the detailed microscopic mechanism underlying the improved performance of the doped system due to atomic defects and demonstrate an effective charge separation strategy to construct highly efficient and stable photocatalytic two-dimensional materials.
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Affiliation(s)
- Sraddha Agrawal
- Department
of Chemistry, University of Southern California, Los Angeles, California 90007, United States
| | - David Casanova
- Donostia
International Physics Center (DIPC), 20018 Donostia, Euskadi, Spain
- IKERBASQUE,
Basque Foundation for Science, 48009 Bilbao, Euskadi, Spain
| | - Dhara J. Trivedi
- Department
of Physics, Clarkson University, Potsdam, New York 13699, United States
| | - Oleg V. Prezhdo
- Department
of Chemistry, University of Southern California, Los Angeles, California 90007, United States
- Department
of Physics and Astronomy, University of
Southern California, Los Angeles, California 90007, United States
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6
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Katiyar AK, Hoang AT, Xu D, Hong J, Kim BJ, Ji S, Ahn JH. 2D Materials in Flexible Electronics: Recent Advances and Future Prospectives. Chem Rev 2024; 124:318-419. [PMID: 38055207 DOI: 10.1021/acs.chemrev.3c00302] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
Flexible electronics have recently gained considerable attention due to their potential to provide new and innovative solutions to a wide range of challenges in various electronic fields. These electronics require specific material properties and performance because they need to be integrated into a variety of surfaces or folded and rolled for newly formatted electronics. Two-dimensional (2D) materials have emerged as promising candidates for flexible electronics due to their unique mechanical, electrical, and optical properties, as well as their compatibility with other materials, enabling the creation of various flexible electronic devices. This article provides a comprehensive review of the progress made in developing flexible electronic devices using 2D materials. In addition, it highlights the key aspects of materials, scalable material production, and device fabrication processes for flexible applications, along with important examples of demonstrations that achieved breakthroughs in various flexible and wearable electronic applications. Finally, we discuss the opportunities, current challenges, potential solutions, and future investigative directions about this field.
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Affiliation(s)
- Ajit Kumar Katiyar
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Anh Tuan Hoang
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Duo Xu
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Juyeong Hong
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Beom Jin Kim
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Seunghyeon Ji
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Jong-Hyun Ahn
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, Republic of Korea
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7
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Yang Y, Zhang Y, Fernandez-Alberti S, Long R. Resolving the Puzzle of Charge Carrier Lifetime in ZnO by Revisiting the Role of Oxygen Vacancy. J Phys Chem Lett 2024; 15:1-8. [PMID: 38126721 DOI: 10.1021/acs.jpclett.3c03195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
Zinc oxide (ZnO) is a wide bandgap prototypical n-type semiconductor due to the presence of intrinsic oxygen vacancies (VO). The VO can readily transfer to the most energetically favorable +2 charged VO (VO2+) by losing two electrons mediated by the metastable VO1+ defect. Nevertheless, the influence of charged VO on the charge dynamics in ZnO and the underlying mechanisms remain elusive. By performing nonadiabatic molecular dynamics simulations of the charge trapping and recombination processes, we show that both VO1+ and VO2+ slow down the nonradiative electron-hole recombination via assisted defect states and, thus, extending charge carrier lifetime compared to pristine ZnO. Our study contributes to identifying the different recombination pathways that take place in VO1+ and VO2+ of n-type ZnO systems, providing useful guidance for designing high-performance ZnO-based devices.
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Affiliation(s)
- Yating Yang
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, P. R. China
- Department of Radiochemistry, China Institute of Atomic Energy, Beijing 102413, P. R. China
| | - Yitong Zhang
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, P. R. China
| | | | - Run Long
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, P. R. China
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8
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Mondal S, Chowdhury U, Dey S, Habib M, Mora Perez C, Frauenheim T, Sarkar R, Pal S, Prezhdo OV. Controlling Charge Carrier Dynamics in Porphyrin Nanorings by Optically Active Templates. J Phys Chem Lett 2023; 14:11384-11392. [PMID: 38078872 PMCID: PMC10749466 DOI: 10.1021/acs.jpclett.3c03304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 12/01/2023] [Accepted: 12/01/2023] [Indexed: 12/22/2023]
Abstract
Understanding the dynamics of photogenerated charge carriers is essential for enhancing the performance of solar and optoelectronic devices. Using atomistic quantum dynamics simulations, we demonstrate that a short π-conjugated optically active template can be used to control hot carrier relaxation, charge carrier separation, and carrier recombination in light-harvesting porphyrin nanorings. Relaxation of hot holes is slowed by 60% with an optically active template compared to that with an analogous optically inactive template. Both systems exhibit subpicosecond electron transfer from the photoactive core to the templates. Notably, charge recombination is suppressed 6-fold by the optically active template. The atomistic time-domain simulations rationalize these effects by the extent of electron and hole localization, modification of the density of states, participation of distinct vibrational motions, and changes in quantum coherence. Extension of the hot carrier lifetime and reduction of charge carrier recombination, without hampering charge separation, demonstrate a strategy for enhancing efficiencies of energy materials with optically active templates.
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Affiliation(s)
- Shrabanti Mondal
- Department
of Chemistry, University of Gour Banga, Malda 732103, India
| | - Uttam Chowdhury
- Department
of Chemistry, University of Gour Banga, Malda 732103, India
| | - Subhajit Dey
- Department
of Chemistry, University of Gour Banga, Malda 732103, India
| | - Md Habib
- Department
of Chemistry, University of Gour Banga, Malda 732103, India
- Department
of Chemistry, Sripat Singh College, Jiaganj 742122, India
| | - Carlos Mora Perez
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Thomas Frauenheim
- Bremen
Center
for Computational Materials Science, Universität
Bremen, Bremen 28359, Germany
- Beijing
Computational Science Research Center, Beijing 100193, China
- Shenzhen
JL Computational Science and Applied Research Institute, Shenzhen 518109, China
| | - Ritabrata Sarkar
- Department
of Chemistry, University of Gour Banga, Malda 732103, India
- Bremen
Center
for Computational Materials Science, Universität
Bremen, Bremen 28359, Germany
| | - Sougata Pal
- Department
of Chemistry, University of Gour Banga, Malda 732103, India
| | - Oleg V. Prezhdo
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089, United States
- Department
of Physics and Astronomy, University of
Southern California, Los Angeles, California 90089, United States
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9
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Lu TF, Chu W, Agrawal S, Zhang Z, Prezhdo OV. Lattice Distortion and Low-Frequency Anharmonic Phonons Suppress Charge Recombination in Lead Halide Perovskites upon Pseudohalide Doping: Time-Domain Ab Initio Analysis. J Phys Chem Lett 2023; 14:10685-10692. [PMID: 37988630 PMCID: PMC10694819 DOI: 10.1021/acs.jpclett.3c02850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 11/15/2023] [Accepted: 11/16/2023] [Indexed: 11/23/2023]
Abstract
Perovskite solar cells have witnessed a surge in interest as a promising technology for low-cost, high-efficiency photovoltaics with certified power conversion efficiencies beyond 25%. However, their commercial development is hindered by poor stability and nonradiative losses that restrict their approach to the theoretical efficiency limit. Using ab initio nonadiabatic molecular dynamics, we demonstrate that nonradiative charge recombination is suppressed when the iodide in formamidinium lead iodide (FAPbI3) is partially replaced with pseudohalide anions (SCN-, BF4-, and PF6-). The replacement breaks the symmetry of the system and creates local structural distortion and dynamic disorder, decreasing electron-hole overlap and nonadiabatic electron-vibrational coupling. The charge carrier lifetime is found to increase with increased structural distortion and is the longest for PF6-. This work is fundamentally relevant to the design of high-performance perovskite materials for optoelectronic applications.
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Affiliation(s)
- Teng-Fei Lu
- School
of Materials Science and Engineering, Dalian
Jiaotong University, Dalian 116028, Liaoning, China
| | - Weibin Chu
- Key
Laboratory of Computational Physical Sciences (Ministry of Education),
Institute of Computational Physical Sciences, Fudan University, Shanghai 200433, China
| | - Sraddha Agrawal
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Zhihua Zhang
- School
of Materials Science and Engineering, Dalian
Jiaotong University, Dalian 116028, Liaoning, China
| | - Oleg V. Prezhdo
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089, United States
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10
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Guo S, Li C, Nie Z, Wang X, Wang M, Tian C, Yan X, Hu K, Long R. Tensile Strain-Dependent Ultrafast Electron Transfer and Relaxation Dynamics in Flexible WSe 2/MoS 2 Heterostructures. J Phys Chem Lett 2023:10920-10929. [PMID: 38033191 DOI: 10.1021/acs.jpclett.3c02943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2023]
Abstract
Understanding and controlling carrier dynamics in two-dimensional (2D) van der Waals heterostructures through strain are crucial for their flexible applications. Here, femtosecond transient absorption spectroscopy is employed to elucidate the interlayer electron transfer and relaxation dynamics under external tensile strains in a WSe2/MoS2 heterostructure. The results show that a modest ∼1% tensile strain can significantly alter the lifetimes of electron transfer and nonradiative electron-hole recombination by >30%. Ab initio non-adiabatic molecular dynamics simulations suggest that tensile strain weakens the electron-phonon coupling, thereby suppressing the transfer and recombination dynamics. Theoretical predictions indicate that strain-induced energy difference increases along the electron transfer path could contribute to the prolongation of the transfer lifetime. A subpicosecond decay process, related to hot-electron cooling, remains almost unaffected by strain. This study demonstrates the potential of tuning interlayer carrier dynamics through external strains, offering insights into flexible optoelectronic device design with 2D materials.
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Affiliation(s)
- Sen Guo
- School of Physical Science and Information Technology, Liaocheng University, Liaocheng, Shandong 252000, China
- FSchool of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Chaofan Li
- School of Physical Science and Information Technology, Liaocheng University, Liaocheng, Shandong 252000, China
| | - Zhaogang Nie
- School of Physical Science and Information Technology, Liaocheng University, Liaocheng, Shandong 252000, China
- FSchool of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Xiaoli Wang
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of the Ministry of Education, Beijing Normal University, Beijing 100875, China
| | - Minghong Wang
- School of Physical Science and Information Technology, Liaocheng University, Liaocheng, Shandong 252000, China
| | - Cunwei Tian
- School of Physical Science and Information Technology, Liaocheng University, Liaocheng, Shandong 252000, China
| | - Xinhua Yan
- Nobat Intelligent Equipment (Shandong), Company, Ltd., Liaocheng, Shandong 252000, China
| | - Kaige Hu
- FSchool of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Run Long
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of the Ministry of Education, Beijing Normal University, Beijing 100875, China
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11
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Ma X, Long R. The sp 3 Defect Decreases Charge Carrier Lifetime in (8,3) Single-Walled Carbon Nanotubes. J Phys Chem Lett 2023; 14:10242-10248. [PMID: 37937588 DOI: 10.1021/acs.jpclett.3c02923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2023]
Abstract
A recent experimental approach introduces sp3 defects into single-walled carbon nanotubes (SWNTs) through controlled functionalization with guanine, resulting in a decrease in charge carrier lifetime. However, the physical mechanism behind this phenomenon remains unclear. We employ nonadiabatic molecular dynamics to systematically model the nonradiative recombination process of electron-hole pairs in SWNTs with sp3 defects generated by a guanine molecule. We demonstrate that the introduction of sp3 defects creates an overlapping channel between the highest occupied (HOMO) and lowest unoccupied molecular orbital (LUMO), significantly enhancing the nonadiabatic (NA) coupling and leading to a 4.7-fold acceleration in charge carrier recombination compared to defect-free SWNTs. The charge carrier recombination slows significantly at a lower temperature (50 K) due to the weakening of the NA coupling. Our results rationalize the accelerated recombination of charge carriers in SWNTs with sp3 defects in experiments and contribute to a deeper understanding of the carrier dynamics in SWNTs.
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Affiliation(s)
- Xinbo Ma
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, P. R. China
| | - Run Long
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, P. R. China
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12
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Wang B, Wu Y, Liu D, Vasenko AS, Casanova D, Prezhdo OV. Efficient Modeling of Quantum Dynamics of Charge Carriers in Materials Using Short Nonequilibrium Molecular Dynamics. J Phys Chem Lett 2023; 14:8289-8295. [PMID: 37681642 PMCID: PMC10518862 DOI: 10.1021/acs.jpclett.3c02187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Accepted: 09/05/2023] [Indexed: 09/09/2023]
Abstract
Nonadiabatic molecular dynamics provides essential insights into excited-state processes, but it is computationally intense and simplifications are needed. The classical path approximation provides critical savings. Still, long heating and equilibration steps are required. We demonstrate that practical results can be obtained with short, partially equilibrated ab initio trajectories. Once the system's structure is adequate and essential fluctuations are sampled, the nonadiabatic Hamiltonian can be constructed. Local structures require only 1-2 ps trajectories, as demonstrated with point defects in metal halide perovskites. Short trajectories represent anharmonic motions common in defective structures, an essential improvement over the harmonic approximation around the optimized geometry. Glassy systems, such as grain boundaries, require different simulation protocols, e.g., involving machine learning force fields. 10-fold shorter trajectories generate 10-20% time scale errors, which are acceptable, given experimental uncertainties and other approximations. The practical NAMD protocol enables fast screening of excited-state dynamics for rapid exploration of new materials.
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Affiliation(s)
- Bipeng Wang
- Department
of Chemical Engineering, University of Southern
California, Los Angeles, California 90089, United States
| | - Yifan Wu
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | | | - Andrey S. Vasenko
- HSE
University, 101000 Moscow, Russia
- Donostia
International Physics Center (DIPC), 20018 San Sebastián-Donostia, Euskadi, Spain
| | - David Casanova
- Donostia
International Physics Center (DIPC), 20018 San Sebastián-Donostia, Euskadi, Spain
- IKERBASQUE, Basque Foundation for Science, 48009 Bilbao, Euskadi, Spain
| | - Oleg V. Prezhdo
- Department
of Chemical Engineering, University of Southern
California, Los Angeles, California 90089, United States
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089, United States
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13
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Vorobyova M, Biffoli F, Giurlani W, Martinuzzi SM, Linser M, Caneschi A, Innocenti M. PVD for Decorative Applications: A Review. MATERIALS (BASEL, SWITZERLAND) 2023; 16:4919. [PMID: 37512195 PMCID: PMC10381906 DOI: 10.3390/ma16144919] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Revised: 07/05/2023] [Accepted: 07/07/2023] [Indexed: 07/30/2023]
Abstract
Physical Vapor Deposition (PVD) is a widely utilized process in various industrial applications, serving as a protective and hard coating. However, its presence in fields like fashion has only recently emerged, as electroplating processes had previously dominated this reality. The future looks toward the replacement of the most hazardous and toxic electrochemical processes, especially those involving Cr(VI) and cyanide galvanic baths, which have been restricted by the European Union. Unfortunately, a complete substitution with PVD coatings is not feasible. Currently, the combination of both techniques is employed to achieve new aesthetic features, including a broader color range and diverse textures, rendering de facto PVD of primary interest for the decorative field and the fashion industry. This review aims to outline the guidelines for decorative industries regarding PVD processes and emphasize the recent advancements, quality control procedures, and limitations.
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Affiliation(s)
- Mariya Vorobyova
- Department of Chemistry "Ugo Schiff", University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy
- National Interuniversity Consortium of Materials Science and Technology (INSTM), Via G. Giusti 9, 50121 Firenze, Italy
| | - Fabio Biffoli
- Department of Chemistry "Ugo Schiff", University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy
| | - Walter Giurlani
- Department of Chemistry "Ugo Schiff", University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy
- National Interuniversity Consortium of Materials Science and Technology (INSTM), Via G. Giusti 9, 50121 Firenze, Italy
| | - Stefano Mauro Martinuzzi
- Department of Chemistry "Ugo Schiff", University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy
- National Interuniversity Consortium of Materials Science and Technology (INSTM), Via G. Giusti 9, 50121 Firenze, Italy
| | | | - Andrea Caneschi
- National Interuniversity Consortium of Materials Science and Technology (INSTM), Via G. Giusti 9, 50121 Firenze, Italy
- Department of Industrial Engineering (DIEF), University of Florence, Via Santa Marta 3, 50139 Firenze, Italy
| | - Massimo Innocenti
- Department of Chemistry "Ugo Schiff", University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy
- National Interuniversity Consortium of Materials Science and Technology (INSTM), Via G. Giusti 9, 50121 Firenze, Italy
- CNR-ICOMM, Insititute of Chemistry of Organometallic Compounds, National Research Council (CNR), Via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy
- CSGI (Center for Colloid and Surface Science), Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy
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14
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Thoutam LR, Mathew R, Ajayan J, Tayal S, Nair SV. A critical review of fabrication challenges and reliability issues in top/bottom gated MoS 2field-effect transistors. NANOTECHNOLOGY 2023; 34:232001. [PMID: 36731113 DOI: 10.1088/1361-6528/acb826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 02/02/2023] [Indexed: 06/18/2023]
Abstract
The voyage of semiconductor industry to decrease the size of transistors to achieve superior device performance seems to near its physical dimensional limitations. The quest is on to explore emerging material systems that offer dimensional scaling to match the silicon- based technologies. The discovery of atomic flat two-dimensional materials has opened up a completely new avenue to fabricate transistors at sub-10 nanometer level which has the potential to compete with modern silicon-based semiconductor devices. Molybdenum disulfide (MoS2) is a two-dimensional layered material with novel semiconducting properties at atomic level seems like a promising candidate that can possibly meet the expectation of Moore's law. This review discusses the various 'fabrication challenges' in making MoS2based electronic devices from start to finish. The review outlines the intricate challenges of substrate selection and various synthesis methods of mono layer and few-layer MoS2. The review focuses on the various techniques and methods to minimize interface defect density at substrate/MoS2interface for optimum MoS2-based device performance. The tunable band-gap of MoS2with varying thickness presents a unique opportunity for contact engineering to mitigate the contact resistance issue using different elemental metals. In this work, we present a comprehensive overview of different types of contact materials with myriad geometries that show a profound impact on device performance. The choice of different insulating/dielectric gate oxides on MoS2in co-planar and vertical geometry is critically reviewed and the physical feasibility of the same is discussed. The experimental constraints of different encapsulation techniques on MoS2and its effect on structural and electronic properties are extensively discussed.
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Affiliation(s)
- Laxman Raju Thoutam
- Amrita School of Nanosciences and Molecular Medicine, Amrita Vishwa Vidyapeetham, Ponekkara, Kochi 682041, India
| | - Ribu Mathew
- School of Electrical & Electronics Engineering, VIT Bhopal University, Bhopal, 466114, India
| | - J Ajayan
- Department of Electronics and Communication Engineering, SR University, Warangal, 506371, India
| | - Shubham Tayal
- Department of Electronics and Communication Engineering, SR University, Warangal, 506371, India
| | - Shantikumar V Nair
- Amrita School of Nanosciences and Molecular Medicine, Amrita Vishwa Vidyapeetham, Ponekkara, Kochi 682041, India
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15
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Giri A, Park G, Jeong U. Layer-Structured Anisotropic Metal Chalcogenides: Recent Advances in Synthesis, Modulation, and Applications. Chem Rev 2023; 123:3329-3442. [PMID: 36719999 PMCID: PMC10103142 DOI: 10.1021/acs.chemrev.2c00455] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The unique electronic and catalytic properties emerging from low symmetry anisotropic (1D and 2D) metal chalcogenides (MCs) have generated tremendous interest for use in next generation electronics, optoelectronics, electrochemical energy storage devices, and chemical sensing devices. Despite many proof-of-concept demonstrations so far, the full potential of anisotropic chalcogenides has yet to be investigated. This article provides a comprehensive overview of the recent progress made in the synthesis, mechanistic understanding, property modulation strategies, and applications of the anisotropic chalcogenides. It begins with an introduction to the basic crystal structures, and then the unique physical and chemical properties of 1D and 2D MCs. Controlled synthetic routes for anisotropic MC crystals are summarized with example advances in the solution-phase synthesis, vapor-phase synthesis, and exfoliation. Several important approaches to modulate dimensions, phases, compositions, defects, and heterostructures of anisotropic MCs are discussed. Recent significant advances in applications are highlighted for electronics, optoelectronic devices, catalysts, batteries, supercapacitors, sensing platforms, and thermoelectric devices. The article ends with prospects for future opportunities and challenges to be addressed in the academic research and practical engineering of anisotropic MCs.
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Affiliation(s)
- Anupam Giri
- Department of Chemistry, Faculty of Science, University of Allahabad, Prayagraj, UP-211002, India
| | - Gyeongbae Park
- Department of Materials Science and Engineering, Pohang University of Science and Technology, Cheongam-Ro 77, Nam-Gu, Pohang, Gyeongbuk790-784, Korea.,Functional Materials and Components R&D Group, Korea Institute of Industrial Technology, Gwahakdanji-ro 137-41, Sacheon-myeon, Gangneung, Gangwon-do25440, Republic of Korea
| | - Unyong Jeong
- Department of Materials Science and Engineering, Pohang University of Science and Technology, Cheongam-Ro 77, Nam-Gu, Pohang, Gyeongbuk790-784, Korea
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16
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Lu M, Ji H, Zhao Y, Chen Y, Tao J, Ou Y, Wang Y, Huang Y, Wang J, Hao G. Machine Learning-Assisted Synthesis of Two-Dimensional Materials. ACS APPLIED MATERIALS & INTERFACES 2023; 15:1871-1878. [PMID: 36574361 DOI: 10.1021/acsami.2c18167] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Two-dimensional (2D) materials have intriguing physical and chemical properties, which exhibit promising applications in the fields of electronics, optoelectronics, as well as energy storage. However, the controllable synthesis of 2D materials is highly desirable but remains challenging. Machine learning (ML) facilitates the development of insights and discoveries from a large amount of data in a short time for the materials synthesis, which can significantly reduce the computational costs and shorten the development cycles. Based on this, taking the 2D material MoS2 as an example, the parameters of successfully synthesized materials by chemical vapor deposition (CVD) were explored through four ML algorithms: XGBoost, Support Vector Machine (SVM), Naïve Bayes (NB), and Multilayer Perceptron (MLP). Recall, specificity, accuracy, and other metrics were used to assess the performance of these four models. By comparison, XGBoost was the best performing model among all the models, with an average prediction accuracy of over 88% and a high area under the receiver operating characteristic (AUROC) reaching 0.91. And these findings showed that the reaction temperature (T) had a crucial influence on the growth of MoS2. Furthermore, the importance of the features in the growth mechanism of MoS2 was optimized, such as the reaction temperature (T), Ar gas flow rate (Rf), reaction time (t), and so on. The results demonstrated that ML assisted materials preparation can significantly minimize the time spent on exploration and trial-and-error, which provided perspectives in the preparation of 2D materials.
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Affiliation(s)
- Mingying Lu
- School of Physics and Optoelectronics, Xiangtan University, Xiangtan, Hunan 411105, P. R. China
| | - Haining Ji
- School of Physics and Optoelectronics, Xiangtan University, Xiangtan, Hunan 411105, P. R. China
| | - Yong Zhao
- School of Physics and Optoelectronics, Xiangtan University, Xiangtan, Hunan 411105, P. R. China
| | - Yongxing Chen
- School of Physics and Optoelectronics, Xiangtan University, Xiangtan, Hunan 411105, P. R. China
| | - Jundong Tao
- School of Physics and Optoelectronics, Xiangtan University, Xiangtan, Hunan 411105, P. R. China
| | - Yangyong Ou
- School of Physics and Optoelectronics, Xiangtan University, Xiangtan, Hunan 411105, P. R. China
| | - Yi Wang
- School of Physics and Optoelectronics, Xiangtan University, Xiangtan, Hunan 411105, P. R. China
| | - Yan Huang
- School of Physics and Optoelectronics, Xiangtan University, Xiangtan, Hunan 411105, P. R. China
| | - Junlong Wang
- School of Physics and Optoelectronics, Xiangtan University, Xiangtan, Hunan 411105, P. R. China
| | - Guolin Hao
- School of Physics and Optoelectronics, Xiangtan University, Xiangtan, Hunan 411105, P. R. China
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17
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Och M, Anastasiou K, Leontis I, Zemignani GZ, Palczynski P, Mostaed A, Sokolikova MS, Alexeev EM, Bai H, Tartakovskii AI, Lischner J, Nellist PD, Russo S, Mattevi C. Synthesis of mono- and few-layered n-type WSe 2 from solid state inorganic precursors. NANOSCALE 2022; 14:15651-15662. [PMID: 36189726 PMCID: PMC9631355 DOI: 10.1039/d2nr03233c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Accepted: 09/05/2022] [Indexed: 06/16/2023]
Abstract
Tuning the charge transport properties of two-dimensional transition metal dichalcogenides (TMDs) is pivotal to their future device integration in post-silicon technologies. To date, co-doping of TMDs during growth still proves to be challenging, and the synthesis of doped WSe2, an otherwise ambipolar material, has been mainly limited to p-doping. Here, we demonstrate the synthesis of high-quality n-type monolayered WSe2 flakes using a solid-state precursor for Se, zinc selenide. n-Type transport has been reported with prime electron mobilities of up to 10 cm2 V-1 s-1. We also demonstrate the tuneability of doping to p-type transport with hole mobilities of 50 cm2 V-1 s-1 after annealing in air. n-Doping has been attributed to the presence of Zn adatoms on the WSe2 flakes as revealed by X-ray photoelectron spectroscopy (XPS), spatially resolved time of flight secondary ion mass spectroscopy (SIMS) and angular dark-field scanning transmission electron microscopy (AD-STEM) characterization of WSe2 flakes. Monolayer WSe2 flakes exhibit a sharp photoluminescence (PL) peak at room temperature and highly uniform emission across the entire flake area, indicating a high degree of crystallinity of the material. This work provides new insight into the synthesis of TMDs with charge carrier control, to pave the way towards post-silicon electronics.
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Affiliation(s)
- Mauro Och
- Department of Materials, Imperial College London, London, SW7 2AZ, UK.
| | | | - Ioannis Leontis
- Department of Physics and Astronomy, University of Exeter, Exeter, EX4 4QL, UK
| | - Giulia Zoe Zemignani
- Department of Materials, Imperial College London, London, SW7 2AZ, UK.
- Center for Nano Science and Technology, Milan, Italy
| | - Pawel Palczynski
- Department of Materials, Imperial College London, London, SW7 2AZ, UK.
| | - Ali Mostaed
- Department of Materials, University of Oxford, Oxford, OX1 3PH, UK
| | | | - Evgeny M Alexeev
- Department of Physics and Astronomy, University of Sheffield, Sheffield, S3 7RH, UK
| | - Haoyu Bai
- Department of Materials, Imperial College London, London, SW7 2AZ, UK.
| | | | - Johannes Lischner
- Department of Materials, Imperial College London, London, SW7 2AZ, UK.
- Thomas Young Centre for Theory and Simulation of Materials, Imperial College London, London, SW7 2AZ, UK
| | - Peter D Nellist
- Department of Materials, University of Oxford, Oxford, OX1 3PH, UK
| | - Saverio Russo
- Department of Physics and Astronomy, University of Exeter, Exeter, EX4 4QL, UK
| | - Cecilia Mattevi
- Department of Materials, Imperial College London, London, SW7 2AZ, UK.
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18
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Li W, Akimov AV. How Good Is the Vibronic Hamiltonian Repetition Approach for Long-Time Nonadiabatic Molecular Dynamics? J Phys Chem Lett 2022; 13:9688-9694. [PMID: 36218389 DOI: 10.1021/acs.jpclett.2c02765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Multiple applied studies of slow nonadiabatic processes in nanoscale and condensed matter systems have adopted the "repetition" approximation in which long trajectories for such simulations are obtained by concatenating shorter trajectories, directly available from ab initio calculations, many times. Here, we comprehensively assess this approximation using model Hamiltonians with parameters covering a wide range of regimes. We find that state transition time scales may strongly depend on the length of the repeated data, although the convergence is not monotonic and may be slow. The repetition approach may under- or overestimate the time scales by a factor of ≤7-8, does not directly depend on the dispersion of energy gap and nonadiabatic coupling (NAC) frequencies, but may depend on the magnitude of the NACs. We suggest that the repetition-based nonadiabatic dynamics may be inaccurate in simulations with very small NACs, where intrinsic transition times are on the order of ≥100 ps.
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Affiliation(s)
- Wei Li
- School of Chemistry and Materials Science, Hunan Agricultural University, Changsha410128, China
| | - Alexey V Akimov
- Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, New York14260, United States
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19
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Shi R, Fang Q, Vasenko AS, Long R, Fang WH, Prezhdo OV. Structural Disorder in Higher-Temperature Phases Increases Charge Carrier Lifetimes in Metal Halide Perovskites. J Am Chem Soc 2022; 144:19137-19149. [PMID: 36206144 DOI: 10.1021/jacs.2c08627] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Solar cells and optoelectronic devices are exposed to heat that degrades performance. Therefore, elucidating temperature-dependent charge carrier dynamics is essential for device optimization. Charge carrier lifetimes decrease with temperature in conventional semiconductors. The opposite, anomalous trend is observed in some experiments performed with MAPbI3 (MA = CH3NH3+) and other metal halide perovskites. Using ab initio quantum dynamics simulation, we establish the atomic mechanisms responsible for nonradiative electron-hole recombination in orthorhombic-, tetragonal-, and cubic MAPbI3. We demonstrate that structural disorder arising from the phase transitions is as important as the disorder due to heating in the same phase. The carrier lifetimes grow both with increasing temperature in the same phase and upon transition to the higher-temperature phases. The increased lifetime is rationalized by structural disorder that induces partial charge localization, decreases nonadiabatic coupling, and shortens quantum coherence. Inelastic and elastic electron-vibrational interactions exhibit opposite dependence on temperature and phase. The partial disorder and localization arise from thermal motions of both the inorganic lattice and the organic cations and depend significantly on the phase. The structural deformations induced by thermal fluctuations and phase transitions are on the same order as deformations induced by defects, and hence, thermal disorder plays a very important role. Since charge localization increases carrier lifetimes but inhibits transport, an optimal regime maximizing carrier diffusion can be designed, depending on phase, temperature, material morphology, and device architecture. The atomistic mechanisms responsible for the enhanced carrier lifetimes at elevated temperatures provide guidelines for the design of improved solar energy and optoelectronic materials.
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Affiliation(s)
- Ran Shi
- Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, College of Chemistry, Beijing Normal University, Beijing100875, People's Republic of China
| | - Qiu Fang
- Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, College of Chemistry, Beijing Normal University, Beijing100875, People's Republic of China
| | | | - Run Long
- Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, College of Chemistry, Beijing Normal University, Beijing100875, People's Republic of China
| | - Wei-Hai Fang
- Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, College of Chemistry, Beijing Normal University, Beijing100875, People's Republic of China
| | - Oleg V Prezhdo
- Departments of Chemistry, and Physics and Astronomy, University of Southern California, Los Angeles, California90089, United States
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20
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Suleman M, Lee S, Kim M, Nguyen VH, Riaz M, Nasir N, Kumar S, Park HM, Jung J, Seo Y. NaCl-Assisted Temperature-Dependent Controllable Growth of Large-Area MoS 2 Crystals Using Confined-Space CVD. ACS OMEGA 2022; 7:30074-30086. [PMID: 36061644 PMCID: PMC9434612 DOI: 10.1021/acsomega.2c03108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 08/10/2022] [Indexed: 06/15/2023]
Abstract
Due to its semiconducting nature, controlled growth of large-area chemical vapor deposition (CVD)-grown two-dimensional (2D) molybdenum disulfide (MoS2) has a lot of potential applications in photodetectors, sensors, and optoelectronics. Yet the controllable, large-area, and cost-effective growth of highly crystalline MoS2 remains a challenge. Confined-space CVD is a very promising method for the growth of highly crystalline MoS2 in a controlled manner. Herein, we report the large-scale growth of MoS2 with different morphologies using NaCl as a seeding promoter for confined-space CVD. Changes in the morphologies of MoS2 are reported by variation in the amount of seeding promoter, precursor ratio, and the growth temperature. Furthermore, the properties of the grown MoS2 are analyzed using optical microscopy, scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), and atomic force microscopy (AFM). The electrical properties of the CVD-grown MoS2 show promising performance from fabricated field-effect transistors. This work provides new insight into the growth of large-area MoS2 and opens the way for its various optoelectronic and electronic applications.
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21
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Sarkar R, Habib M, Pal S. Symmetrical Linkage in Porphyrin Nanoring Suppressed the Electron-Hole Recombination Demonstrated by Nonadiabatic Molecular Dynamics. J Phys Chem Lett 2022; 13:7213-7219. [PMID: 35912962 DOI: 10.1021/acs.jpclett.2c02073] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Macromolecular porphyrin nanorings are receiving significant attention because of their excellent optoelectronic properties. However, their efficiencies as potential solar materials are significantly affected by nonradiative charge recombination. To understand the recombination mechanism by alternating structural parameters and using tight-binding nonadiabatic molecular dynamics, we demonstrate that charge recombination depends strongly on the mode of the linker in the porphyrin nanoring. The nanoring having all-butadiyne-linkage (pristine-P8) inhibits carrier relaxation. In contrast, a partially fused nanoring (fused-P8) expedites the rate of quantum transition. An extension of the lifetime by a factor of 4 is due to the larger optical gap in pristine-P8 that reduces the NA coupling by decreasing the overlap between band edge states. Additionally, an intense phonon peak in the low-frequency region and rapid coherence loss within the electronic subsystem favors prolonging the carrier lifetime. This study provides an atomistic realization for the design of macromolecular porphyrin nanorings for the potential use in photovoltaic materials.
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Affiliation(s)
- Ritabrata Sarkar
- Department of Chemistry, University of Gour Banga, Malda 732103, India
- Bremen Center for Computational Materials Science, Universität Bremen, Bremen 28359, Germany
| | - Md Habib
- Department of Chemistry, University of Gour Banga, Malda 732103, India
- Department of Chemistry, Sripat Singh College, Jiaganj 742122, India
| | - Sougata Pal
- Department of Chemistry, University of Gour Banga, Malda 732103, India
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22
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Zhang L, Chu W, Zheng Q, Zhao J. Effects of oxygen vacancies on the photoexcited carrier lifetime in rutile TiO 2. Phys Chem Chem Phys 2022; 24:4743-4750. [PMID: 35142307 DOI: 10.1039/d1cp04248c] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The photoexcited carrier lifetime in semiconductors plays a crucial role in solar energy conversion processes. The defects or impurities in semiconductors are usually proposed to introduce electron-hole (e-h) recombination centers and consequently reduce the photoexcited carrier lifetime. In this report, we investigate the effects of oxygen vacancies (OV) on the carrier lifetime in rutile TiO2, which has important applications in photocatalysis and photovoltaics. It is found that an OV introduces two excess electrons which form two defect states in the band gap. The lower state is localized on one Ti atom and behaves as a small polaron, and the higher one is a hybrid state contributed by three Ti atoms around the OV. Both the polaron and hybrid states exhibit strong electron-phonon (e-ph) coupling and their charge distributions become more and more delocalized when the temperature increases from 100 to 700 K. Such strong e-ph coupling and charge delocalization enhance the nonadibatic coupling between the electronic states along the hole relaxation path, where the defect states behave as intermediate states, leading to a distinct acceleration of e-h recombination. Our study provides valuable insights to understand the role of defects on photoexcited carrier lifetime in semiconductors.
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Affiliation(s)
- Lili Zhang
- Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China. .,Key Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, China
| | - Weibin Chu
- Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China. .,Departments of Chemistry, and Physics and Astronomy, University of Southern California, Los Angeles, CA 90089, USA
| | - Qijing Zheng
- Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
| | - Jin Zhao
- Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
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23
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Ayodele OO, Adesina AO, Pourianejad S, Averitt J, Ignatova T. Recent Advances in Nanomaterial-Based Aptasensors in Medical Diagnosis and Therapy. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:932. [PMID: 33917467 PMCID: PMC8067492 DOI: 10.3390/nano11040932] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 03/25/2021] [Accepted: 03/30/2021] [Indexed: 02/07/2023]
Abstract
Rapid and accurate diagnosis of various biomarkers associated with medical conditions including early detection of viruses and bacteria with highly sensitive biosensors is currently a research priority. Aptamer is a chemically derived recognition molecule capable of detecting and binding small molecules with high specificity and its fast preparation time, cost effectiveness, ease of modification, stability at high temperature and pH are some of the advantages it has over traditional detection methods such as High Performance Liquid Chromatography (HPLC), Enzyme-linked Immunosorbent Assay (ELISA), Polymerase Chain Reaction (PCR). Higher sensitivity and selectivity can further be achieved via coupling of aptamers with nanomaterials and these conjugates called "aptasensors" are receiving greater attention in early diagnosis and therapy. This review will highlight the selection protocol of aptamers based on Traditional Systematic Evolution of Ligands by EXponential enrichment (SELEX) and the various types of modified SELEX. We further identify both the advantages and drawbacks associated with the modified version of SELEX. Furthermore, we describe the current advances in aptasensor development and the quality of signal types, which are dependent on surface area and other specific properties of the selected nanomaterials, are also reviewed.
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Affiliation(s)
| | | | | | | | - Tetyana Ignatova
- Nanoscience Department, The Joint School of Nanoscience & Nanoengineering, University of North Carolina, Greensboro, NC 27401, USA; (O.O.A.); (A.O.A.); (S.P.); (J.A.)
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24
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Dou W, Jia Y, Hao X, Meng Q, Wu J, Zhai S, Li T, Hu W, Song B, Zhou M. Time-Domain Ab Initio Insights into the Reduced Nonradiative Electron-Hole Recombination in ReSe 2/MoS 2 van der Waals Heterostructure. J Phys Chem Lett 2021; 12:2682-2690. [PMID: 33689347 DOI: 10.1021/acs.jpclett.1c00455] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Two-dimensional (2D) ReSe2 has attracted considerable interest due to its unique anisotropic mechanical, optical, and exitonic characteristics. Recent transient absorption experiments demonstrated a prolonged lifetime of photoexcited charge carriers by stacking ReSe2 with MoS2, but the underlying mechanism remains elusive. Here, by combining time-domain density functional theory with nonadiabatic molecular dynamics, we investigate the electronic properties and charge carrier dynamics of 2D ReSe2/MoS2 van der Waals (vdW) heterostructure. ReSe2/MoS2 has a type II band alignment that exhibits spatially distinguished conduction and valence band edges, and a built-in electric field is formed due to interface charge transfer. Remarkably, in spite of the decreased band gap and increased decoherence time, we demonstrate that the photocarrier lifetime of ReSe2/MoS2 is ∼5 times longer than that of ReSe2, which originates from the greatly reduced nonadiabatic coupling that suppresses electron-hole recombination, perfectly explaining the experimental results. These findings not only provide physical insights into experiments but also shed light on future design and fabrication of functional optoelectronic devices based on 2D vdW heterostructures.
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Affiliation(s)
- Wenzhen Dou
- School of Physics, Beihang University, Beijing 100191, China
| | - Yizhen Jia
- School of Physics, Beihang University, Beijing 100191, China
| | - Xiamin Hao
- School of Physics, Beihang University, Beijing 100191, China
| | - Qingling Meng
- School of Physics, Beihang University, Beijing 100191, China
| | - Jinge Wu
- School of Physics, Beihang University, Beijing 100191, China
| | - Shuwei Zhai
- School of Physics, Beihang University, Beijing 100191, China
| | - Tianzhao Li
- School of Physics, Beihang University, Beijing 100191, China
| | - Weijuan Hu
- School of Physics, Beihang University, Beijing 100191, China
| | - Biyu Song
- School of Physics, Beihang University, Beijing 100191, China
| | - Miao Zhou
- School of Physics, Beihang University, Beijing 100191, China
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25
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Zhang L, Chu W, Zhao C, Zheng Q, Prezhdo OV, Zhao J. Dynamics of Photoexcited Small Polarons in Transition-Metal Oxides. J Phys Chem Lett 2021; 12:2191-2198. [PMID: 33630612 DOI: 10.1021/acs.jpclett.1c00003] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The dynamics of photoexcited polarons in transition-metal oxides (TMOs), including their formation, migration, and quenching, plays an important role in photocatalysis and photovoltaics. Taking rutile TiO2 as a prototypical system, we use ab initio nonadiabatic molecular dynamics simulation to investigate the dynamics of small polarons induced by photoexcitation at different temperatures. The photoexcited electron is trapped by the distortion of the surrounding lattice and forms a small polaron within tens of femtoseconds. Polaron migration among Ti atoms is strongly correlated with quenching through an electron-hole (e-h) recombination process. At low temperature, the polaron is localized on a single Ti atom and polaron quenching occurs within several nanoseconds. At increased temperature, as under solar cell operating conditions, thermal phonon excitation stimulates the hopping and delocalization of polarons, which induces fast polaron quenching through the e-h recombination within 200 ps. Our study proves that e-h recombination centers can be formed by photoexcited polarons, which provides new insights to understand the efficiency bottleneck of photocatalysis and photovoltaics in TMOs.
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Affiliation(s)
- Lili Zhang
- Key Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, China
| | - Weibin Chu
- Departments of Chemistry, and Physics and Astronomy, University of Southern California, Los Angeles, California 90089, United States
| | | | | | - Oleg V Prezhdo
- Departments of Chemistry, and Physics and Astronomy, University of Southern California, Los Angeles, California 90089, United States
| | - Jin Zhao
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh Pennsylvania 15260, United States
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26
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Bertoldo F, Unocic RR, Lin YC, Sang X, Puretzky AA, Yu Y, Miakota D, Rouleau CM, Schou J, Thygesen KS, Geohegan DB, Canulescu S. Intrinsic Defects in MoS 2 Grown by Pulsed Laser Deposition: From Monolayers to Bilayers. ACS NANO 2021; 15:2858-2868. [PMID: 33576605 DOI: 10.1021/acsnano.0c08835] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Pulsed laser deposition (PLD) can be considered a powerful method for the growth of two-dimensional (2D) transition-metal dichalcogenides (TMDs) into van der Waals heterostructures. However, despite significant progress, the defects in 2D TMDs grown by PLD remain largely unknown and yet to be explored. Here, we combine atomic resolution images and first-principles calculations to reveal the atomic structure of defects, grains, and grain boundaries in mono- and bilayer MoS2 grown by PLD. We find that sulfur vacancies and MoS antisites are the predominant point defects in 2D MoS2. We predict that the aforementioned point defects are thermodynamically favorable under a Mo-rich/S-poor environment. The MoS2 monolayers are polycrystalline and feature nanometer size grains connected by a high density of grain boundaries. In particular, the coalescence of nanometer grains results in the formation of 180° mirror twin boundaries consisting of distinct 4- and 8-membered rings. We show that PLD synthesis of bilayer MoS2 results in various structural symmetries, including AA' and AB, but also turbostratic with characteristic moiré patterns. Moreover, we report on the experimental demonstration of an electron beam-driven transition between the AB and AA' stacking orientations in bilayer MoS2. These results provide a detailed insight into the atomic structure of monolayer MoS2 and the role of the grain boundaries on the growth of bilayer MoS2, which has importance for future applications in optoelectronics.
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Affiliation(s)
- Fabian Bertoldo
- CAMD and Center for Nanostructured Graphene (CNG), Department of Physics, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Raymond R Unocic
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Yu-Chuan Lin
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Xiahan Sang
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 430070 Wuhan, China
| | - Alexander A Puretzky
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Yiling Yu
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Denys Miakota
- Department of Photonics Engineering, Technical University of Denmark, 4000 Roskilde, Denmark
| | - Christopher M Rouleau
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Jørgen Schou
- Department of Photonics Engineering, Technical University of Denmark, 4000 Roskilde, Denmark
| | - Kristian S Thygesen
- CAMD and Center for Nanostructured Graphene (CNG), Department of Physics, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - David B Geohegan
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Stela Canulescu
- Department of Photonics Engineering, Technical University of Denmark, 4000 Roskilde, Denmark
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27
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Gokul MA, Narayanan V, Rahman A. Modulating flow near substrate surface to grow clean and large-area monolayer MoS 2. NANOTECHNOLOGY 2020; 31:415706. [PMID: 32570232 DOI: 10.1088/1361-6528/ab9ed6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Chemical vapour deposition (CVD) is one of the most promising methods to synthesize monolayers of 2D materials like transition metal dichalcogenides (TMDs) over a large area with high film quality. Among many parameters that determine the growth of 2D materials, flow of precursor near the surface is one of the most sensitive conditions. In this study, we show how subtle changes in the flow near the substrate surface can affect the quality and coverage of the MoS2 monolayer. We fine tune the flow of the carrier gas near the substrate under two extreme conditions to grow large area and clean monolayer. In the first study, we grew several centimetres long continuous monolayer under the condition, which generally produces monolayers of few tens of micrometres in size without tuning the flow on the substrate surface. In the second case, we got monolayer MoS2 under the conditions meant for the formation of bulk MoS2.We achieved this by placing blockades on the substrate surface which helped in modifying the flow near them. Through simulation, we showed how the flow is affected near these blockades and used it as a guiding rule to grow patterned continuous MoS2 monolayers. Detailed electrical and optical measurements were done to determine the quality of the as-grown samples. Our studies provide a way to obtain clean, large area monolayer of desired pattern by tuning the flow of precursor on the vicinity of the substrate surface even when the growth conditions in CVD are far from optimum.
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Affiliation(s)
- M A Gokul
- Department of Physics, Indian Institute for Science Education and Research (IISER)-Pune, Dr. Homi Bhabha Road, Pune 411008, India
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28
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Agrawal S, Lin W, Prezhdo OV, Trivedi DJ. Ab initio quantum dynamics of charge carriers in graphitic carbon nitride nanosheets. J Chem Phys 2020; 153:054701. [PMID: 32770911 DOI: 10.1063/5.0010628] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Graphitic carbon nitride (g-C3N4), a metal-free and visible light responsive photocatalyst, has garnered much attention due to its wide range of applications. In order to elucidate the role of dimensionality on the properties of photo-generated charge carriers, we apply nonadiabatic (NA) molecular dynamics combined with time-domain density functional theory to investigate nonradiative relaxation of hot electrons and holes, and electron-hole recombination in monolayer and bulk g-C3N4. The nonradiative charge recombination occurs on a nanosecond timescale and is faster in bulk than the nanosheet, in agreement with the experiment. The difference arises due to the smaller energy gap and participation of additional vibrations in the bulk system. The long carrier lifetimes are favored by small NA coupling and rapid phonon-induced loss of quantum coherence between the excited and ground electronic states. Decoherence is fast because g-C3N4 is soft and undergoes large scale vibrations. The NA coupling is small since electrons and holes are localized on different atoms, and the electron-hole overlap is relatively small. Phonon-driven relaxation of hot electrons and holes takes 100-200 fs and is slightly slower at higher initial energies due to participation of fewer vibrational modes. This feature of two-dimensional g-C3N4 contrasts traditional three-dimensional semiconductors, which exhibit faster relaxation at higher energies due to larger density of states, and can be used to extract hot carriers to perform useful functions. The ab initio quantum dynamics simulations present a comprehensive picture of the photo-induced charge carrier dynamics in g-C3N4, guiding design of photovoltaic and photocatalytic devices.
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Affiliation(s)
- Sraddha Agrawal
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Wei Lin
- State Key Laboratory of Photocatalysis on Energy and Environment, College of Chemistry, Fuzhou University, Fuzhou 350108, People's Republic of China
| | - Oleg V Prezhdo
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Dhara J Trivedi
- Department of Physics, Clarkson University, Potsdam, New York 13699, USA
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29
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Wei Y, Tokina MV, Benderskii AV, Zhou Z, Long R, Prezhdo OV. Quantum dynamics origin of high photocatalytic activity of mixed-phase anatase/rutile TiO2. J Chem Phys 2020; 153:044706. [DOI: 10.1063/5.0014179] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Yaqing Wei
- College of Chemistry, Key Laboratory of Theoretical and Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, People’s Republic of China
| | - Marina V. Tokina
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Alexander V. Benderskii
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Zhaohui Zhou
- Chemical Engineering and Technology, School of Environmental Science and Engineering, Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region, Ministry of Education, Chang’an University, Xi’an 710064, China
| | - Run Long
- College of Chemistry, Key Laboratory of Theoretical and Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, People’s Republic of China
| | - Oleg V. Prezhdo
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
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30
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He J, Casanova D, Fang WH, Long R, Prezhdo OV. MAI Termination Favors Efficient Hole Extraction and Slow Charge Recombination at the MAPbI 3/CuSCN Heterojunction. J Phys Chem Lett 2020; 11:4481-4489. [PMID: 32423207 DOI: 10.1021/acs.jpclett.0c01467] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Photoinduced charge separation is the key step determining the efficiency of photon-to-electron conversion in solar cells, while charge carrier lifetimes govern the overall solar cell performance. Experiments report that copper(I) thiocyanate (CuSCN) is a very promising hole extraction layer for perovskite solar cells. Using nonadiabatic molecular dynamics combined with ab initio time-domain density functional theory, we show that termination of CH3NH3PbI3 (MAPbI3) at MAPbI3/CuSCN heterojunctions has a strong influence on both charge separation and recombination. Both processes are favored by MAI termination, compared to PbI2 termination. Because the MAPbI3 valence band originates from iodine orbitals while the conduction band arises from Pb orbitals, MAI termination places holes close to CuSCN, favoring extraction, and creates an MAI barrier for recombination of electrons in MAPbI3 and holes in CuSCN. The opposite is true for PbI2 termination. The origin of these effects is attributed solely to the properties of the MAPbI3 surfaces, and therefore, the conclusions should apply to other hole-transporting materials and can be generalized to other perovskites. Importantly, the simulations show that the injected hole remains hot for several hundreds of femtoseconds, allowing it to escape the interfacial region and prevent formation of bound excitons. This study suggests that metal halide perovskites should be treated with an organic precursor, such as MAI, prior to the formation of their interfaces with hole-transporting materials. The reported results advance the fundamental understanding of the highly unusual properties of metal halide perovskites and provide specific guidelines for optimizing the performance of perovskite solar cells and other devices.
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Affiliation(s)
- Jinlu He
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, P. R. China
| | - David Casanova
- Donostia International Physics Center (DIPC), 20018 Donostia, Euskadi, Spain
- IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Euskadi, Spain
| | - Wei-Hai Fang
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, P. R. China
| | - Run Long
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, P. R. China
| | - Oleg V Prezhdo
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
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31
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Lu TF, Wang YS, Tomko JA, Hopkins PE, Zhang HX, Prezhdo OV. Control of Charge Carrier Dynamics in Plasmonic Au Films by TiO x Substrate Stoichiometry. J Phys Chem Lett 2020; 11:1419-1427. [PMID: 32011143 DOI: 10.1021/acs.jpclett.9b03884] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Plasmonic excitations in noble metals have many fascinating properties and give rise to a broad range of applications. We demonstrate, using nonadiabatic molecular dynamics combined with time-domain density functional theory, that the chemical composition and stoichiometry of substrates can have a strong influence on charge dynamics. By changing oxygen content in TiO2, including stoichiometric, oxygen rich, and oxygen poor phases, and Ti metal, one can alter lifetimes of charge carriers in Au by a factor of 5 and control the ratio of electron-to-hole relaxation rates by a factor of 10. Remarkably, a thin TiOx substrate greatly alters charge carrier properties in much thicker Au films. Such large variations stem from the fact that the Ti and O atoms are much lighter than Au, and their vibrations are much faster at dissipating the energy. The control over a particular charge carrier and an energy range depends on the Au and TiOx level alignment, and the interfacial interaction strength. These factors are easily influenced by the TiOx stoichiometry. In particular, oxygen rich and poor TiO2 can be used to control holes and electrons, respectively, while metallic Ti affects both charge carriers. The detailed atomistic analysis of the interfacial and electron-vibrational interactions generates the fundamental understanding of the properties of plasmonic materials needed to design photovoltaic, photocatalytic, optoelectronic, sensing, nanomedical, and other devices.
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Affiliation(s)
- Teng-Fei Lu
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry , Jilin University , Changchun 130023 , People's Republic of China
- Department of Chemistry , University of Southern California , Los Angeles , California 90089 , United States
| | - Yi-Siang Wang
- Department of Chemistry , University of Southern California , Los Angeles , California 90089 , United States
| | - John A Tomko
- Department of Materials Science and Engineering , University of Virginia , Charlottesville , Virginia 22904 , United States
| | - Patrick E Hopkins
- Department of Materials Science and Engineering , University of Virginia , Charlottesville , Virginia 22904 , United States
- Department of Mechanical and Aerospace Engineering , University of Virginia , Charlottesville , Virginia 22904 , United States
- Department of Physics , University of Virginia , Charlottesville , Virginia 22904 , United States
| | - Hong-Xing Zhang
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry , Jilin University , Changchun 130023 , People's Republic of China
| | - Oleg V Prezhdo
- Department of Chemistry , University of Southern California , Los Angeles , California 90089 , United States
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32
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Zhang Z, Qiao L, Mora-Perez C, Long R, Prezhdo OV. Pb dimerization greatly accelerates charge losses in MAPbI3: Time-domain ab initio analysis. J Chem Phys 2020; 152:064707. [DOI: 10.1063/1.5131342] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Zhaosheng Zhang
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, People’s Republic of China
| | - Lu Qiao
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, People’s Republic of China
| | - Carlos Mora-Perez
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Run Long
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, People’s Republic of China
| | - Oleg V. Prezhdo
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
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33
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Agafonov V, Nargelienė V, Balakauskas S, Bukauskas V, Kamarauskas M, Lukša A, Mironas A, Rėza A, Šetkus A. Single variable defined technology control of the optical properties in MoS 2 films with controlled number of 2D-layers. NANOTECHNOLOGY 2020; 31:025602. [PMID: 31550684 DOI: 10.1088/1361-6528/ab4753] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Fabrication of practical devices based on the transient metal dichalcogenides (TMDs) can be successively extended to various areas of the applications if the large area growth technology can be intentionally controlled and the characteristics of the layers can be easily predicted. In present work we presented the principles of the technology control based on the single key variable that can be directly related to the sequence of the technological processes. The atomically thin MoS2 layers were used as a model material and the layers were obtained by the CVD synthesis of the molybdenum precursor. Our thorough study demonstrated that the method allowed to deliberately choose the number of the MoS2 two-dimensional (2D)-layers between 1 and 10 by simply choosing the precursor deposition time. The optical properties of the layers were characterised by the optical transitions that corresponded to the known band structure of the MoS2 layers. Fused calibration diagram was proposed as the practical tool for the technology control and it was proved to be highly successive in relating the 2D-properties of the films with the initial stage of the fabrication technology. The method can be adapted to the wafer size TMDs growth on the diverse substrates.
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Affiliation(s)
- Vladimir Agafonov
- Department of Physical Technologies, Center for Physical Sciences and Technology, Sauletekio av. 3, LT-10257 Vilnius, Lithuania
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34
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Yang Y, Fang WH, Benderskii A, Long R, Prezhdo OV. Strain Controls Charge Carrier Lifetimes in Monolayer WSe 2: Ab Initio Time Domain Analysis. J Phys Chem Lett 2019; 10:7732-7739. [PMID: 31755714 DOI: 10.1021/acs.jpclett.9b03105] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Mono- and few-layer transition metal dichalcogenides (TMDs) are among the most appealing candidates for electronic and optoelectronic devices. During synthesis, TMDs actively interact with substrates, which induce notable strain and influence significantly charge carriers in TMDs. By performing time-domain ab initio simulations on monolayer WSe2, we demonstrate that charge carrier lifetimes vary by a factor of 3 within a typical 1% strain range, the bandgap changes by 0.2 eV, and electron-phonon interactions vary by 60%. Fortuitously, the most common tensile strain extends the lifetimes. The changes arise because of modifications in interatomic interactions. Further, compared to the optimized structure, at ambient temperature the bandgap drops by 0.1 eV and fluctuates by 0.1 eV. WSe2 obeys linear response within 1% strain; however, further strain leads to nonlinear qualitative changes in WSe2 electronic properties. The conduction band is affected more strongly than the valence band. Charges couple to phonons within a 100-400 cm-1 frequency range, with the strongest coupling to in-plane and out-of-plane modes at 250 cm-1. The reported findings agree with the available experiments and should be generic to other 2D materials. The strain effects need to be considered during TMD synthesis and provide means to control and tune TMD properties for 2D device applications.
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Affiliation(s)
- Yating Yang
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education , Beijing Normal University , Beijing 100875 , P.R. China
| | - Wei-Hai Fang
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education , Beijing Normal University , Beijing 100875 , P.R. China
| | - Alex Benderskii
- Department of Chemistry , University of Southern California , Los Angeles , California 90089 , United States
| | - Run Long
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education , Beijing Normal University , Beijing 100875 , P.R. China
| | - Oleg V Prezhdo
- Department of Chemistry , University of Southern California , Los Angeles , California 90089 , United States
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35
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Zhou G, Cen C, Wang S, Deng M, Prezhdo OV. Electron-Phonon Scattering Is Much Weaker in Carbon Nanotubes than in Graphene Nanoribbons. J Phys Chem Lett 2019; 10:7179-7187. [PMID: 31644293 DOI: 10.1021/acs.jpclett.9b02874] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Carbon nanotubes (CNTs) and graphene nanoribbons (GNRs) are lower-dimensional derivatives of graphene. Similar to graphene, they exhibit high charge mobilities; however, in contrast to graphene, they are semiconducting and thus are suitable for electronics, optics, solar energy devices, and other applications. Charge carrier mobilities, energies, and lifetimes are governed by scattering with phonons, and we demonstrate, using ab initio nonadiabatic molecular dynamics, that charge-phonon scattering is much stronger in GNRs. Focusing on a GNR and a CNT of similar size and electronic properties, we show that the difference arises because of the significantly higher stiffness of the CNT. The GNR undergoes large-scale undulating motions at ambient conditions. Such thermal geometry distortions localize wave functions, accelerate both elastic and inelastic charge-phonon scattering, and increase the rates of energy and carrier losses. Even though, formally, both CNTs and GNRs are quantum confined derivatives of graphene, charge-phonon scattering differs significantly between them. Showing good agreement with time-resolved photoconductivity and photoluminescence measurements, the study demonstrates that GNRs are quite similar to molecules, such as conjugated polymers, while CNTs exhibit extended features attributed to bulk materials. The state-of-the-art simulations alter the traditional view of graphene nanostructures and demonstrate that the performance can be tuned not only by size and composition but also by stiffness and response to thermal excitation.
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Affiliation(s)
- Guoqing Zhou
- Guizhou Provincial Key Laboratory of Computational Nano-material Science , Guizhou Education University , Guiyang 550018 , China
- Department of Physics and Astronomy , University of Southern California , Los Angeles , California 90089 , United States
| | - Chao Cen
- Guizhou Provincial Key Laboratory of Computational Nano-material Science , Guizhou Education University , Guiyang 550018 , China
| | - Shuyi Wang
- Guizhou Provincial Key Laboratory of Computational Nano-material Science , Guizhou Education University , Guiyang 550018 , China
| | - Mingsen Deng
- Guizhou Provincial Key Laboratory of Computational Nano-material Science , Guizhou Education University , Guiyang 550018 , China
| | - Oleg V Prezhdo
- Department of Physics and Astronomy , University of Southern California , Los Angeles , California 90089 , United States
- Department of Chemistry , University of Southern California , Los Angeles , California 90089 , United States
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36
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Lei L, Huang D, Zeng G, Cheng M, Jiang D, Zhou C, Chen S, Wang W. A fantastic two-dimensional MoS2 material based on the inert basal planes activation: Electronic structure, synthesis strategies, catalytic active sites, catalytic and electronics properties. Coord Chem Rev 2019. [DOI: 10.1016/j.ccr.2019.213020] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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37
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Zhang L, Chu W, Zheng Q, Benderskii AV, Prezhdo OV, Zhao J. Suppression of Electron-Hole Recombination by Intrinsic Defects in 2D Monoelemental Material. J Phys Chem Lett 2019; 10:6151-6158. [PMID: 31553184 DOI: 10.1021/acs.jpclett.9b02620] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The Shockley-Read-Hall (SRH) model, in which the deep trap defect states in the band gap are proposed as nonradiative electron-hole (e-h) recombination centers, has been widely used to describe the nonradiative e-h recombination through the defects in semiconductor. By using the ab initio nonadiabatic molecular dynamics method, we find that the SRH model fails to describe the e-h recombination behavior for defects in 2D monoelemental material such as monolayer black phosphorus (BP). Through the investigation of three intrinsic defects with shallow and deep defect states in monolayer BP, it is found that, surprisingly, none of these defects significantly accelerates the e-h recombination. Further analysis shows that because monolayer BP is a monoelemental material, the distinct impurity phonon, which often induces fast e-h recombination, is not formed. Moreover, because of the flexibility of 2D material, the defects scatter the phonons present in pristine BP, generating multiple modes with lower frequencies compared with the pristine BP, which further suppresses the e-h recombination. We propose that the conclusion can be extended to other monoelemental 2D materials, which is important guidance for the future design of functional semiconductors.
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Affiliation(s)
- Lili Zhang
- ICQD/Hefei National Laboratory for Physical Sciences at Microscale, and Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences, and Department of Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
- Department of Chemistry , University of Southern California , Los Angeles , California 90089 , United States
| | - Weibin Chu
- ICQD/Hefei National Laboratory for Physical Sciences at Microscale, and Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences, and Department of Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
- Department of Chemistry , University of Southern California , Los Angeles , California 90089 , United States
| | - Qijing Zheng
- ICQD/Hefei National Laboratory for Physical Sciences at Microscale, and Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences, and Department of Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
- Synergetic Innovation Center of Quantum Information & Quantum Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Alexander V Benderskii
- Department of Chemistry , University of Southern California , Los Angeles , California 90089 , United States
| | - Oleg V Prezhdo
- Department of Chemistry , University of Southern California , Los Angeles , California 90089 , United States
| | - Jin Zhao
- ICQD/Hefei National Laboratory for Physical Sciences at Microscale, and Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences, and Department of Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
- Synergetic Innovation Center of Quantum Information & Quantum Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
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38
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Li W, Vasenko AS, Tang J, Prezhdo OV. Anharmonicity Extends Carrier Lifetimes in Lead Halide Perovskites at Elevated Temperatures. J Phys Chem Lett 2019; 10:6219-6226. [PMID: 31556621 DOI: 10.1021/acs.jpclett.9b02553] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Lead halide perovskites constitute a very promising class of materials for a broad range of solar and optoelectronic applications. Perovskites exhibit many unusual properties, and recent experiments demonstrate an unusual temperature dependence of charge carrier lifetimes. Focusing on the all-inorganic CsPbBr3, and using a combination of ab initio nonadiabatic molecular dynamics and time-domain density functional theory, we demonstrate that the unconventional behavior arises because of a highly anharmonic nature of atomic motions in perovskites. As temperature increases, perovskite structure undergoes a notable deformation, reflected in tilting of octahedral units, and experiences large-scale anharmonic movements away from the equilibrium geometry. As a result, the electronic energy gap increases, and phonon-induced loss of coherence within the electronic subsystem accelerates. These two factors slow down nonradiative electron-hole recombination, which constitutes the main limitation on efficiencies of perovskite solar, optical, and electronic devices. The increase of charge carrier lifetimes with temperature is particularly beneficial in applications, because materials heat up, for instance, from sunlight during solar energy harvesting. The behavior of the all-inorganic halide perovskite investigated here is different from that of hybrid organic-inorganic perovskites, which exhibit additional disorder associated with reorientations of the asymmetric organic cations. The reported simulations generate an in-depth understanding of the unusual properties of inorganic perovskites, relevant for photocatalytic, photovoltaic, electronic, and optical applications.
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Affiliation(s)
- Wei Li
- College of Science , Hunan Agricultural University , Changsha 410128 , People's Republic of China
| | - Andrey S Vasenko
- National Research University Higher School of Economics , 101000 Moscow , Russia
| | - Jianfeng Tang
- College of Science , Hunan Agricultural University , Changsha 410128 , People's Republic of China
| | - Oleg V Prezhdo
- Department of Chemistry , University of Southern California , Los Angeles , California 90089 , United States
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39
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Song B, Liu L, Yam C. Suppressed Carrier Recombination in Janus MoSSe Bilayer Stacks: A Time-Domain Ab Initio Study. J Phys Chem Lett 2019; 10:5564-5570. [PMID: 31475829 DOI: 10.1021/acs.jpclett.9b02048] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Janus transition metal dichalcogenides (TMDs) have recently emerged as a new class of two-dimensional materials with a vertical dipole moment. Here, using time-domain ab initio simulations, we show that electron-hole recombination can be substantially suppressed via different stacking orientations of bilayer MoSSe. Despite having a larger net dipole moment, a S-Se/S-Se oriented MoSSe bilayer has a shorter carrier lifetime due to strong nonadiabatic coupling and a small band gap. The electron-hole recombination is coupled to the interlayer out-of-plane motion. In contrast, the opposite vertical dipoles weaken interlayer interactions in symmetric oriented MoSSe bilayers. Consequently, initial and final states are localized within different layers, and this significantly suppresses carrier recombination, resulting in an order of magnitude longer excited carrier lifetime in Se-S/S-Se oriented MoSSe bilayers. Our simulations provide theoretical insights into the carrier dynamics and suggest a way to enhance the carrier lifetime in Janus TMDs for efficient energy harvesting.
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Affiliation(s)
- Bing Song
- Beijing Computational Science Research Center , Haidian District, Beijing 100193 , China
| | - Limin Liu
- Beijing Computational Science Research Center , Haidian District, Beijing 100193 , China
- School of Physics , Beihang University , Beijing 100083 , China
| | - ChiYung Yam
- Beijing Computational Science Research Center , Haidian District, Beijing 100193 , China
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40
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Li L, Lin MF, Zhang X, Britz A, Krishnamoorthy A, Ma R, Kalia RK, Nakano A, Vashishta P, Ajayan P, Hoffmann MC, Fritz DM, Bergmann U, Prezhdo OV. Phonon-Suppressed Auger Scattering of Charge Carriers in Defective Two-Dimensional Transition Metal Dichalcogenides. NANO LETTERS 2019; 19:6078-6086. [PMID: 31434484 DOI: 10.1021/acs.nanolett.9b02005] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Two-dimensional transition metal dichalcogenides (TMDs) draw strong interest in materials science, with applications in optoelectronics and many other fields. Good performance requires high carrier concentrations and long lifetimes. However, high concentrations accelerate energy exchange between charged particles by Auger-type processes, especially in TMDs where many-body interactions are strong, thus facilitating carrier trapping. We report time-resolved optical pump-THz probe measurements of carrier lifetimes as a function of carrier density. Surprisingly, the lifetime reduction with increased density is very weak. It decreases only by 20% when we increase the pump fluence 100 times. This unexpected feature of the Auger process is rationalized by our time-domain ab initio simulations. The simulations show that phonon-driven trapping competes successfully with the Auger process. On the one hand, trap states are relatively close to band edges, and phonons accommodate efficiently the electronic energy during the trapping. On the other hand, trap states localize around defects, and the overlap of trapped and free carriers is small, decreasing carrier-carrier interactions. At low carrier densities, phonons provide the main charge trapping mechanism, decreasing carrier lifetimes compared to defect-free samples. At high carrier densities, phonons suppress Auger processes and lower the dependence of the trapping rate on carrier density. Our results provide theoretical insights into the diverse roles played by phonons and Auger processes in TMDs and generate guidelines for defect engineering to improve device performance at high carrier densities.
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Affiliation(s)
- Linqiu Li
- Department of Chemistry , University of Southern California , Los Angeles , California 90089 , United States
| | - Ming-Fu Lin
- Linac Coherent Light Source , SLAC National Accelerator Laboratory , Menlo Park , California 94025 , United States
| | - Xiang Zhang
- Department of Materials Science and Nanoengineering , Rice University , Houston , Texas 77005 , United States
| | - Alexander Britz
- Linac Coherent Light Source , SLAC National Accelerator Laboratory , Menlo Park , California 94025 , United States
- Stanford PULSE Institute , SLAC National Accelerator Laboratory , Menlo Park , California 94025 , United States
| | - Aravind Krishnamoorthy
- Collaboratory for Advanced Computing and Simulations, Department of Physics &Astronomy, Department of Computer Science, Department of Chemical Engineering & Materials Science, Department of Biological Sciences , University of Southern California , Los Angeles , California 90089 , United States
| | - Ruru Ma
- Collaboratory for Advanced Computing and Simulations, Department of Physics &Astronomy, Department of Computer Science, Department of Chemical Engineering & Materials Science, Department of Biological Sciences , University of Southern California , Los Angeles , California 90089 , United States
| | - Rajiv K Kalia
- Collaboratory for Advanced Computing and Simulations, Department of Physics &Astronomy, Department of Computer Science, Department of Chemical Engineering & Materials Science, Department of Biological Sciences , University of Southern California , Los Angeles , California 90089 , United States
| | - Aiichiro Nakano
- Collaboratory for Advanced Computing and Simulations, Department of Physics &Astronomy, Department of Computer Science, Department of Chemical Engineering & Materials Science, Department of Biological Sciences , University of Southern California , Los Angeles , California 90089 , United States
| | - Priya Vashishta
- Collaboratory for Advanced Computing and Simulations, Department of Physics &Astronomy, Department of Computer Science, Department of Chemical Engineering & Materials Science, Department of Biological Sciences , University of Southern California , Los Angeles , California 90089 , United States
| | - Pulickel Ajayan
- Department of Materials Science and Nanoengineering , Rice University , Houston , Texas 77005 , United States
| | - Matthias C Hoffmann
- Linac Coherent Light Source , SLAC National Accelerator Laboratory , Menlo Park , California 94025 , United States
| | - David M Fritz
- Linac Coherent Light Source , SLAC National Accelerator Laboratory , Menlo Park , California 94025 , United States
| | - Uwe Bergmann
- Stanford PULSE Institute , SLAC National Accelerator Laboratory , Menlo Park , California 94025 , United States
| | - Oleg V Prezhdo
- Department of Chemistry , University of Southern California , Los Angeles , California 90089 , United States
- Department of Physics & Astronomy , University of Southern California , Los Angeles , California 90089 , United States
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41
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Zhang Z, Fang WH, Long R, Prezhdo OV. Exciton Dissociation and Suppressed Charge Recombination at 2D Perovskite Edges: Key Roles of Unsaturated Halide Bonds and Thermal Disorder. J Am Chem Soc 2019; 141:15557-15566. [DOI: 10.1021/jacs.9b06046] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Zhaosheng Zhang
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, People’s Republic of China
| | - Wei-Hai Fang
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, People’s Republic of China
| | - Run Long
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, People’s Republic of China
| | - Oleg V. Prezhdo
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
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42
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Xie XY, Liu XY, Fang Q, Fang WH, Cui G. Photoinduced Carrier Dynamics at the Interface of Pentacene and Molybdenum Disulfide. J Phys Chem A 2019; 123:7693-7703. [PMID: 31419385 DOI: 10.1021/acs.jpca.9b04728] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Understanding of photoinduced interfacial carrier dynamics in organic-transition metal dichalcogenides heterostructures is very important for the enhancement of their potential photoelectronic conversion efficiencies. In this work we have used density functional theory (DFT) calculations and DFT-based fewest-switches surface-hopping dynamics simulations to explore the photoinduced hole transfer and subsequent nonadiabatic electron-hole recombination dynamics taking place at the interface of pentacene and MoS2 in pentacene@MoS2. Upon photoexcitation the electronic transition mainly occurs on the MoS2 monolayer, which corresponds to moving an electron to the MoS2 conduction band. As a result, a hole is left in the valence band. This hole state is energetically lower than certain occupied states of the pentacene molecule; thus, the interfacial hole transfer from MoS2 to pentacene is favorable in energy. In terms of nonadiabatic dynamics simulations, the hole transfer time to the HOMO-1 state of the pentacene is estimated to be about 600 fs; however, the following hole relaxation process from HOMO-1 to HOMO takes much longer time of ca. 15 ps due to the large energy gap between HOMO-1 and HOMO. Moreover, our results also show that the subsequent radiationless recombination process between the hole transferred to the pentacene molecule and the remaining electron on the MoS2 CBM needs about 10.2 ns. The computational results shed important mechanistic insights on the interfacial carrier dynamics of mixed-dimensional pentacene@MoS2. These insights could help to design excellent interfaces for organic-TMDs heterostructures.
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Affiliation(s)
- Xiao-Ying Xie
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry , Beijing Normal University , Beijing 100875 , China
| | - Xiang-Yang Liu
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry , Beijing Normal University , Beijing 100875 , China
| | - Qiu Fang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry , Beijing Normal University , Beijing 100875 , China
| | - Wei-Hai Fang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry , Beijing Normal University , Beijing 100875 , China
| | - Ganglong Cui
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry , Beijing Normal University , Beijing 100875 , China
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Wei W, Huang B, Dai Y. Photoexcited charge carrier behaviors in solar energy conversion systems from theoretical simulations. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2019. [DOI: 10.1002/wcms.1441] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Wei Wei
- School of Physics, State Key Laboratory of Crystal Materials Shandong University Jinan China
| | - Baibiao Huang
- School of Physics, State Key Laboratory of Crystal Materials Shandong University Jinan China
| | - Ying Dai
- School of Physics, State Key Laboratory of Crystal Materials Shandong University Jinan China
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44
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Li W, Long R, Tang J, Prezhdo OV. Influence of Defects on Excited-State Dynamics in Lead Halide Perovskites: Time-Domain ab Initio Studies. J Phys Chem Lett 2019; 10:3788-3804. [PMID: 31244263 DOI: 10.1021/acs.jpclett.9b00641] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
This Perspective summarizes recent research into the excited-state dynamics in lead halide perovskites that are of paramount importance for photovoltaic and photocatalytic applications. Nonadiabatic molecular dynamics combined with time-domain ab initio density functional theory allows one to mimic time-resolved spectroscopy experiments at the atomistic level of detail. The focus is placed on realistic aspects of perovskite materials, including point defects, surfaces, grain boundaries, mixed stoichiometries, dopants, and interfaces. The atomistic description of the quantum dynamics of electron and hole trapping and recombination, provided by the time-domain ab initio simulations, generates important insights into the mechanisms of charge and energy losses and guides the development of high-performance perovskite solar cell devices.
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Affiliation(s)
- Wei Li
- College of Science , Hunan Agricultural University , Changsha 410128 , People's Republic of China
| | - Run Long
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education , Beijing Normal University , Beijing 100875 , People's Republic of China
| | - Jianfeng Tang
- College of Science , Hunan Agricultural University , Changsha 410128 , People's Republic of China
| | - Oleg V Prezhdo
- Department of Chemistry , University of Southern California , Los Angeles , California 90089 , United States
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45
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Nam Y, Li L, Lee JY, Prezhdo OV. Strong Influence of Oxygen Vacancy Location on Charge Carrier Losses in Reduced TiO 2 Nanoparticles. J Phys Chem Lett 2019; 10:2676-2683. [PMID: 31066278 DOI: 10.1021/acs.jpclett.9b00987] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Oxygen vacancies in TiO2 nanoparticles are important for charge carrier dynamics, with recent studies reporting contradictory results on TiO2 nanoparticle photocatalytic activity. We demonstrate that ground state multiplicity, defect levels, and formation energies depend strongly on vacancy location. Quantum dynamics simulations show that charges are trapped within several picoseconds and recombine over a broad range of time scales from tens of picoseconds to nanoseconds. Specifically, nanoparticles with missing partially coordinated surface oxygens showed fast recombination, while nanoparticles with missing highly coordinated subsurface oxygens or singly coordinated oxygens at tips showed slow recombination, even slower than in the pristine system. The results are rationalized by energy gaps and electron-hole localization, the latter determining nonadiabatic coupling and quantum coherence time. The diverse charge recombination scenarios revealed by the nonadiabatic dynamics simulations rationalize the contradictory experimental results for photocatalytic activity and provide guidelines for rational design of nanoscale metal oxides for solar energy harvesting and utilization.
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Affiliation(s)
- Yeonsig Nam
- Department of Chemistry , Sungkyunkwan University , Suwon 16419 , Korea
- Department of Chemistry , University of Southern California , Los Angeles , California 90089 , United States
| | - Linqiu Li
- Department of Chemistry , University of Southern California , Los Angeles , California 90089 , United States
| | - Jin Yong Lee
- Department of Chemistry , Sungkyunkwan University , Suwon 16419 , Korea
| | - Oleg V Prezhdo
- Department of Chemistry , University of Southern California , Los Angeles , California 90089 , United States
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46
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Zhou X, Tokina MV, Tomko JA, Braun JL, Hopkins PE, Prezhdo OV. Thin Ti adhesion layer breaks bottleneck to hot hole relaxation in Au films. J Chem Phys 2019; 150:184701. [DOI: 10.1063/1.5096901] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- Xin Zhou
- College of Environment and Chemical Engineering, Dalian University, Dalian 116622, People’s Republic of China
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Marina V. Tokina
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - John A. Tomko
- Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22903, USA
| | - Jeffrey L. Braun
- Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22903, USA
| | - Patrick E. Hopkins
- Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22903, USA
- Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22903, USA
- Department of Physics, University of Virginia, Charlottesville, Virginia 22903, USA
| | - Oleg V. Prezhdo
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089, USA
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47
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Wang S, Luo Q, Fang WH, Long R. Interfacial Engineering Determines Band Alignment and Steers Charge Separation and Recombination at an Inorganic Perovskite Quantum Dot/WS 2 Junction: A Time Domain Ab Initio Study. J Phys Chem Lett 2019; 10:1234-1241. [PMID: 30818951 DOI: 10.1021/acs.jpclett.9b00285] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Using time-domain density functional theory and nonadiabatic (NA) molecular dynamics, we demonstrate that interfacial interaction between WS2 and CsPbBr3 quantum dots (QDs) determines the band alignment, leading to a type-II and type-I heterojunction for the WS2 contacting with Cs/Br- and PbBr2-terminated facet QD, respectively. In the type-II heterojunction, electron transfer is faster than hole transfer arising due to the stronger NA coupling, higher density of electron acceptor states, and more and higher phonon modes involved. Both the electron and hole transfer times are subpicosecond, in agreement with experiments. The energy lost by the electron and hole is slower than charge transfer by several times, facilitating keeping charge carriers sufficiently "hot". Particularly, the electron-hole recombination occurs over 1 ns, favoring a long-lived charge-separated state. Detailed atomistic insights into the photoinduced charge and energy dynamics at the WS2/QD interface provide valuable guidelines for improving performance of perovskite/transition-metal dichalcogenide solar cells.
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Affiliation(s)
- Siyu Wang
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education , Beijing Normal University , Beijing 100875 , People's Republic of China
| | - Qiquan Luo
- Hefei National Laboratory for Physical Sciences at the Microscale , University of Science and Technology of China , Hefei 230026 , People's Republic of China
| | - Wei-Hai Fang
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education , Beijing Normal University , Beijing 100875 , People's Republic of China
| | - Run Long
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education , Beijing Normal University , Beijing 100875 , People's Republic of China
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48
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Zhang L, Vasenko AS, Zhao J, Prezhdo OV. Mono-Elemental Properties of 2D Black Phosphorus Ensure Extended Charge Carrier Lifetimes under Oxidation: Time-Domain Ab Initio Analysis. J Phys Chem Lett 2019; 10:1083-1091. [PMID: 30777762 DOI: 10.1021/acs.jpclett.9b00042] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
An attractive two-dimensional semiconductor with tunable direct bandgap and high carrier mobility, black phosphorus (BP), is used in batteries, solar cells, photocatalysis, plasmonics, and optoelectronics. BP is sensitive to ambient conditions, with oxygen playing a critical role in structure degradation. Our simulations show that BP oxidation slows down charge recombination. This is unexpected, since typically charges are trapped and lost on defects. First, BP has no ionic character. It interacts with oxygen and water weakly, experiencing little perturbation to electronic structure. Second, phosphorus supports different oxidation states and binds extraneous atoms avoiding deep defect levels. Third, soft BP structure can accommodate foreign species without disrupting periodic geometry. Finally, BP phonon scattering on defects shortens quantum coherence and suppresses recombination. Thus, oxidation can be regarded as production of a self-protective layer that improves BP properties. These BP features should be common to other monoelemental 2D materials, stimulating energy and electronics applications.
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Affiliation(s)
- Lili Zhang
- ICQD/Hefei National Laboratory for Physical Sciences at Microscale, and Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences, and Department of Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
- Department of Chemistry , University of Southern California , Los Angeles , California 90089 , United States
| | - Andrey S Vasenko
- National Research University Higher School of Economics , 101000 Moscow , Russia
| | - Jin Zhao
- ICQD/Hefei National Laboratory for Physical Sciences at Microscale, and Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences, and Department of Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
- Synergetic Innovation Center of Quantum Information & Quantum Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Oleg V Prezhdo
- Department of Chemistry , University of Southern California , Los Angeles , California 90089 , United States
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Nguyen TK, Nguyen AD, Le CT, Ullah F, Tahir Z, Koo KI, Kim E, Kim DW, Jang JI, Kim YS. High Photoresponse in Conformally Grown Monolayer MoS 2 on a Rugged Substrate. ACS APPLIED MATERIALS & INTERFACES 2018; 10:40824-40830. [PMID: 30387344 DOI: 10.1021/acsami.8b15673] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Conformal growth of atomic-thick semiconductor layers on patterned substrates can boost up the performance of electronic and optoelectronic devices remarkably. However, conformal growth is a very challenging technological task, since the control of the growth processes requires utmost precision. Herein, we report on conformal growth and characterization of monolayer MoS2 on planar, microrugged, and nanorugged SiO2/Si substrates via metal-organic chemical vapor deposition. The continuous and conformal nature of monolayer MoS2 on the rugged surface was verified by high-resolution transmission electron microscopy. Strain effects were examined by photoluminescence (PL) and Raman spectroscopy. Interestingly, the photoresponsivity (∼254.5 mA/W) of as-grown MoS2 on the nanorugged substrate was 59 times larger than that of the planar sample (4.3 mA/W) under a small applied bias of 0.1 V. This value is record high when compared with all previous MoS2-based photocurrent generation under low or zero bias. Such enhancement in the photoresponsivity arises from a large active area for light-matter interaction and local strain for PL quenching, wherein the latter effect is the key factor and unique in the conformally grown monolayer on the nanorugged surface.
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Affiliation(s)
| | | | | | | | | | | | - Eunah Kim
- Department of Physics , Ewha Womans University , Seoul 03760 , South Korea
| | - Dong-Wook Kim
- Department of Physics , Ewha Womans University , Seoul 03760 , South Korea
| | - Joon I Jang
- Department of Physics , Sogang University , Seoul 04107 , South Korea
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50
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Liu XY, Xie XY, Fang WH, Cui G. Theoretical Insights into Interfacial Electron Transfer between Zinc Phthalocyanine and Molybdenum Disulfide. J Phys Chem A 2018; 122:9587-9596. [DOI: 10.1021/acs.jpca.8b07816] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Xiang-Yang Liu
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Xiao-Ying Xie
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Wei-Hai Fang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Ganglong Cui
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
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