1
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Aydin A, Keski-Rahkonen J, Heller EJ. Quantum acoustics unravels Planckian resistivity. Proc Natl Acad Sci U S A 2024; 121:e2404853121. [PMID: 38968118 PMCID: PMC11253009 DOI: 10.1073/pnas.2404853121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Accepted: 06/05/2024] [Indexed: 07/07/2024] Open
Abstract
Strange metals exhibit universal linear-in-temperature resistivity described by a Planckian scattering rate, the origin of which remains elusive. By employing an approach inspired by quantum optics, we arrive at the coherent state representation of lattice vibrations: quantum acoustics. Utilizing this nonperturbative framework, we demonstrate that lattice vibrations could serve as active drivers in the Planckian resistivity phenomenon, challenging prevailing theories. By treating charge carriers as quantum wave packets negotiating the dynamic acoustic field, we find that a competition ensues between localization and delocalization giving rise to the previously conjectured universal quantum bound of diffusion, [Formula: see text], independent of temperature or any other material parameters. This leads to the enigmatic T-linear resistivity over hundreds of degrees, except at very low temperatures. Quantum diffusion also explains why strange metals have much higher electrical resistivity than typical metals. Our work elucidates the critical role of phonons in Planckian resistivity from a unique perspective and reconsiders their significance in the transport properties of strange metals.
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Affiliation(s)
- Alhun Aydin
- Department of Physics, Harvard University, 02138Cambridge, MA
- Faculty of Engineering and Natural Sciences, Sabanci University, 34956Tuzla, Istanbul, Türkiye
| | - Joonas Keski-Rahkonen
- Department of Physics, Harvard University, 02138Cambridge, MA
- Computational Physics Laboratory, Tampere University, FI-33101Tampere, Finland
| | - Eric J. Heller
- Department of Physics, Harvard University, 02138Cambridge, MA
- Department of Chemistry and Chemical Biology, Harvard University, 02138Cambridge, MA
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2
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Navamani K. Unified Entropy-Ruled Einstein's Relation for Bulk and Low-Dimensional Molecular-Material Systems: A Hopping-to-Band Shift Paradigm. J Phys Chem Lett 2024; 15:2519-2528. [PMID: 38411901 DOI: 10.1021/acs.jpclett.3c02513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
We present a unified paradigm on entropy-ruled Einstein's diffusion-mobility relation (μ/D ratio) for 1D, 2D, and 3D free-electron solid state systems. The localization transport in the extended molecules is well approximated by the continuum time-delayed hopping factor within our unified entropy-ruled transport method of noninteracting quantum systems. Moreover, we generalize an entropy-dependent diffusion relation for 1D, 2D, and 3D systems as defined by D d , h e f f = D d , h e f f = 0 exp ( ( d - 1 ) h e f f d + 2 ) , where heff and d are the effective entropy and dimension (d = 1, 2, 3), respectively. This generalized relation is valid for both equilibrium and nonequilibrium transport systems since the parameter heff is closely connected with the nonequilibrium fluctuation theorem-based entropy production rule. Importantly, we herein revisit the Boltzmann approach using an entropy-ruled method for mobility calculation for the universal quantum materials that is expressed as μ d = [ ( d d + 2 ) q d h e f f d η ] v F 2 τ 2 , where v F 2 τ 2 is the diffusion constant for band transport systems and η is the chemical potential. According to our entropy-ruled μ/D relation, the Navamani-Shockley diode equation is transformed.
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Affiliation(s)
- K Navamani
- Department of Physics, Centre for Research and Development (CFRD), KPR Institute of Engineering and Technology, Coimbatore-641407, India
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3
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Li Z, Florian M, Datta K, Jiang Z, Borsch M, Wen Q, Kira M, Deotare PB. Enhanced Exciton Drift Transport through Suppressed Diffusion in One-Dimensional Guides. ACS NANO 2023; 17:22410-22417. [PMID: 37874891 DOI: 10.1021/acsnano.3c04870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2023]
Abstract
Drift-diffusion dynamics is investigated in a one-dimensional (1D) exciton guide at room temperature. Spatial engineering of the exciton energy in a WSe2 monolayer is achieved using local strain to confine and direct exciton transport. An unexpected and massive deviation from the Einstein relation is observed and correlated to exciton capture by defects. We find that the capture reduces exciton temperature and diffusion so much that drift transport visibility improves to 38% as excitons traverse asymmetrically over regions with occupied defect states. Based on measurements over multiple potential gradients, we estimate the exciton mobility to be 169 ± 39 cm2/(eV s) at room temperature. Experiments at elevated exciton densities reveal that the exciton drift velocity monotonically increases with exciton density, unlike exciton mobility, due to contributions from nonequilibrium many-body effects.
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Affiliation(s)
- Zidong Li
- Electrical and Computer Engineering Department, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Matthias Florian
- Electrical and Computer Engineering Department, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Kanak Datta
- Electrical and Computer Engineering Department, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Zhaohan Jiang
- Electrical and Computer Engineering Department, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Markus Borsch
- Electrical and Computer Engineering Department, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Qiannan Wen
- Electrical and Computer Engineering Department, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Mack Kira
- Electrical and Computer Engineering Department, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Parag B Deotare
- Electrical and Computer Engineering Department, University of Michigan, Ann Arbor, Michigan 48109, United States
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4
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Navamani K. Quantum-Classical Transition Analogy of the Diffusion-Mobility Relation for Hopping and Band Transport Systems: Molecules to Materials. ACS OMEGA 2023; 8:16009-16015. [PMID: 37179606 PMCID: PMC10173316 DOI: 10.1021/acsomega.2c08046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Accepted: 04/11/2023] [Indexed: 05/15/2023]
Abstract
We propose a quantum-classical transition analogy for Einstein's diffusion-mobility (D/μ) relation to reveal electron-hole dynamics in both the degenerate and nondegenerate molecular and material systems. Here, one-to-one variation between differential entropy and chemical potential (Δη/Δhs) is the proposed analogy, which unifies quantum and classical transport. The degeneracy stabilization energy on D/μ decides whether the transport is quantum or classical; accordingly, the transformation occurs in the Navamani-Shockley diode equation.
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5
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Jašinskas V, Franckevičius M, Gelžinis A, Chmeliov J, Gulbinas V. Direct Tracking of Charge Carrier Drift and Extraction from Perovskite Solar Cells by Means of Transient Electroabsorption Spectroscopy. ACS APPLIED ELECTRONIC MATERIALS 2023; 5:317-326. [PMID: 38616982 PMCID: PMC11008527 DOI: 10.1021/acsaelm.2c01346] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 01/01/2023] [Indexed: 04/16/2024]
Abstract
The best perovskite solar cells currently demonstrate more than 25% efficiencies, yet many fundamental processes that determine the operation of these devices are still not fully understood. In particular, even though the device performance strongly depends on charge carrier transport across the perovskite layer to selective electrodes, information about this process is still very controversial. Here, we investigate charge carrier motion and extraction from an archetypical CH3NH3PbI3 (MAPI) perovskite solar cell. We use the ultrafast electric-field-modulated transient absorption technique, which allows us to evaluate the electric field dynamics from the time-resolved electroabsorption spectra and to visualize the motion of charge carriers with subpicosecond time resolution. We demonstrate that photogenerated holes drift across the mesoporous TiO2/perovskite layer during hundreds of picoseconds. On the other hand, their extraction into the spiro-OMeTAD hole transporting layer lasts for more than 1 nanosecond, suggesting that the hole extraction is limited by the perovskite/spiro-OMeTAD interface rather than by the hole transport through the perovskite layer. Additionally, we use the ultrafast time-resolved fluorescence technique that reveals fluorescence decay during tens of picoseconds, which we attribute to the spatial separation of electrons and holes.
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Affiliation(s)
- Vidmantas Jašinskas
- Department
of Molecular Compound Physics, Center for
Physical Sciences and Technology, Saulėtekio av. 3, VilniusLT-10257, Lithuania
| | - Marius Franckevičius
- Department
of Molecular Compound Physics, Center for
Physical Sciences and Technology, Saulėtekio av. 3, VilniusLT-10257, Lithuania
| | - Andrius Gelžinis
- Department
of Molecular Compound Physics, Center for
Physical Sciences and Technology, Saulėtekio av. 3, VilniusLT-10257, Lithuania
- Institute
of Chemical Physics, Faculty of Physics, Vilnius University, Saulėtekio av. 9, VilniusLT-10222, Lithuania
| | - Jevgenij Chmeliov
- Department
of Molecular Compound Physics, Center for
Physical Sciences and Technology, Saulėtekio av. 3, VilniusLT-10257, Lithuania
- Institute
of Chemical Physics, Faculty of Physics, Vilnius University, Saulėtekio av. 9, VilniusLT-10222, Lithuania
| | - Vidmantas Gulbinas
- Department
of Molecular Compound Physics, Center for
Physical Sciences and Technology, Saulėtekio av. 3, VilniusLT-10257, Lithuania
- Institute
of Chemical Physics, Faculty of Physics, Vilnius University, Saulėtekio av. 9, VilniusLT-10222, Lithuania
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6
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Spiechowicz J, Marchenko IG, Hänggi P, Łuczka J. Diffusion Coefficient of a Brownian Particle in Equilibrium and Nonequilibrium: Einstein Model and Beyond. ENTROPY (BASEL, SWITZERLAND) 2022; 25:42. [PMID: 36673183 PMCID: PMC9857877 DOI: 10.3390/e25010042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 12/21/2022] [Accepted: 12/21/2022] [Indexed: 06/17/2023]
Abstract
The diffusion of small particles is omnipresent in many processes occurring in nature. As such, it is widely studied and exerted in almost all branches of sciences. It constitutes such a broad and often rather complex subject of exploration that we opt here to narrow our survey to the case of the diffusion coefficient for a Brownian particle that can be modeled in the framework of Langevin dynamics. Our main focus centers on the temperature dependence of the diffusion coefficient for several fundamental models of diverse physical systems. Starting out with diffusion in equilibrium for which the Einstein theory holds, we consider a number of physical situations outside of free Brownian motion and end by surveying nonequilibrium diffusion for a time-periodically driven Brownian particle dwelling randomly in a periodic potential. For this latter situation the diffusion coefficient exhibits an intriguingly non-monotonic dependence on temperature.
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Affiliation(s)
- Jakub Spiechowicz
- Institute of Physics, University of Silesia in Katowice, 41-500 Chorzów, Poland
| | - Ivan G. Marchenko
- Institute of Physics, University of Silesia in Katowice, 41-500 Chorzów, Poland
- Kharkiv Institute of Physics and Technology, 61108 Kharkiv, Ukraine
- Education and Research Institute of Computer Physics and Energy, Karazin Kharkiv National University, 61022 Kharkiv, Ukraine
| | - Peter Hänggi
- Institute of Physics, University of Augsburg, 86135 Augsburg, Germany
- Max-Planck Institute for Physics of Complex Systems, 01187 Dresden, Germany
| | - Jerzy Łuczka
- Institute of Physics, University of Silesia in Katowice, 41-500 Chorzów, Poland
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7
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Buhl J, Lüder H, Gerken M. Injection-limited and space charge-limited currents in organic semiconductor devices with nanopatterned metal electrodes. NANOTECHNOLOGY 2022; 34:035202. [PMID: 36179674 DOI: 10.1088/1361-6528/ac9686] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 09/30/2022] [Indexed: 06/16/2023]
Abstract
Charge injection at metal-organic interfaces often limits the electric current in organic light-emitting diodes without additional injection layers. Integrated nanopatterned electrodes may provide a way to overcome this current injection limit by local field enhancements leading to locally space charge-limited currents. We compare electrical characteristics of planar and nanopatterned hole-only devices based on the charge transport material NPB with different thicknesses in order to investigate the nanopattern's effect on the current limitation mechanism. Integration of a periodic nanograting into the metal electrode yields a current increase of about 1.5-4 times, depending on thickness and operating voltage. To verify the experimental results, we implement a finite element simulation model that solves the coupled Poisson and drift-diffusion equations in a weak form. It includes space charges, drift and diffusion currents, nonlinear mobility, and charge injection at the boundaries. We find in experiment and simulation that the planar devices exhibit injection-limited currents, whereas the currents in the nanopatterned devices are dominated by space charge effects, overcoming the planar injection limit. The simulations show space charge accumulations at the corners of the nanopattern, confirming the idea of locally space charge-limited currents.
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Affiliation(s)
- Janek Buhl
- Chair for Integrated Systems and Photonics, Faculty of Engineering, Kiel University, Kaiserstraße 2, D-24143 Kiel, Germany
- Kiel Nano, Surface and Interface Science KiNSIS, Kiel University, Christian-Albrechts-Platz 4, D-24118 Kiel, Germany
| | - Hannes Lüder
- Chair for Integrated Systems and Photonics, Faculty of Engineering, Kiel University, Kaiserstraße 2, D-24143 Kiel, Germany
- Kiel Nano, Surface and Interface Science KiNSIS, Kiel University, Christian-Albrechts-Platz 4, D-24118 Kiel, Germany
| | - Martina Gerken
- Chair for Integrated Systems and Photonics, Faculty of Engineering, Kiel University, Kaiserstraße 2, D-24143 Kiel, Germany
- Kiel Nano, Surface and Interface Science KiNSIS, Kiel University, Christian-Albrechts-Platz 4, D-24118 Kiel, Germany
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8
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Navamani K, Rajkumar K. Generalization on Entropy-Ruled Charge and Energy Transport for Organic Solids and Biomolecular Aggregates. ACS OMEGA 2022; 7:27102-27115. [PMID: 35967056 PMCID: PMC9366796 DOI: 10.1021/acsomega.2c01118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 07/13/2022] [Indexed: 05/27/2023]
Abstract
Herein, a generalized version of the entropy-ruled charge and energy transport mechanism for organic solids and biomolecular aggregates is presented. The effects of thermal disorder and electric field on electronic transport in molecular solids have been quantified by entropy, which eventually varies with respect to the typical disorder (static or dynamic). Based on our previous differential entropy (h s )-driven charge transport method, we explore the nonsteady carrier energy flux principle for soft matter systems from small organic solids to macrobiomolecular aggregates. Through this principle, the synergic nature of charge and energy transport in different organic systems is addressed. In this work, entropy is the key parameter to classify whether the carrier dynamics is in a nonsteady or steady state. Besides that, we also propose the formulation for unifying the hopping and band transport, which provides the relaxation time-hopping rate relation and the relaxation time-effective mass ratio. The calculated disorder drift time (or entropy-weighted carrier drift time) for hole transport in an alkyl-substituted triphenylamine (TPA) molecular device is 9.3 × 10-7 s, which illustrates nuclear dynamics-coupled charge transfer kinetics. The existence of nonequilibrium transport is anticipated while the carrier dynamics is in the nonsteady state, which is further examined from the rate of traversing potential in octupolar molecules. Our entropy-ruled Einstein model connects the adiabatic band and nonadiabatic hopping transport mechanisms. The logarithmic current density at different electric field-assisted site energy differences provides information about the typical transport (whether trap-free diffusion or trap-assisted recombination) in molecular devices, which reflects in the Navamani-Shockley diode equation.
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Affiliation(s)
- Karuppuchamy Navamani
- Department
of Physics, Centre for Research and Development
(CFRD), KPR Institute of Engineering and Technology, Coimbatore 641407, India
| | - Kanakaraj Rajkumar
- Department
of Physics, Indian Institute of Technology
Madras, Chennai 600036, India
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9
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de Melo Neto CA, Pereira ML, Ribeiro LA, Roncaratti LF, da Silva Filho DA. Theoretical prediction of electron mobility in birhodanine crystals and their sulfur analogs. Chem Phys Lett 2021. [DOI: 10.1016/j.cplett.2020.138226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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10
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Li T, Xu L, Xiao X, Chen F, Cao L, Wu W, Tong W, Zhang F. Enhanced Spin Transport of Conjugated Polymer in the Semiconductor/Insulating Polymer Blend. ACS APPLIED MATERIALS & INTERFACES 2020; 12:2708-2716. [PMID: 31894693 DOI: 10.1021/acsami.9b16602] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Conjugated polymers are of high potential in the development of spintronic devices. In this paper, we report systematic studies on spin transport properties of a semiconducting polymer PBDTTT-C-T in the permalloy/polymer/Pt trilayer using the spin pumping method. Pure spin current with long spin relaxation time is observed via the inverse spin Hall effect (ISHE) measurements. Furthermore, spin current is also found to propagate through the blend film consisting of a small amount of PBDTTT-C-T in an insulating matrix. The polymer blend exhibits a remarkably enhanced spin relaxation length (56 nm) and carrier mobility compared to pristine PBDTTT-C-T. From film microstructural characterizations, we propose that the enhanced spin/carrier transport properties are attributed to the formation of interlinked nanonetwork comprising of the PBDTTT-C-T chain bundles in the inert matrix to afford efficient intrachain charge conduction pathway. Temperature- dependent ISHE measurements support the spin-orbit coupling dominated spin relaxation mechanism.
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Affiliation(s)
- Tian Li
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Condition, High Magnetic Field Laboratory (HMFL) , Chinese Academy of Sciences , Hefei , Anhui 230031 , China
- University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Liqiang Xu
- University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Xuhua Xiao
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Condition, High Magnetic Field Laboratory (HMFL) , Chinese Academy of Sciences , Hefei , Anhui 230031 , China
- University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Feng Chen
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Condition, High Magnetic Field Laboratory (HMFL) , Chinese Academy of Sciences , Hefei , Anhui 230031 , China
| | - Liang Cao
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Condition, High Magnetic Field Laboratory (HMFL) , Chinese Academy of Sciences , Hefei , Anhui 230031 , China
| | - Wenbin Wu
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Condition, High Magnetic Field Laboratory (HMFL) , Chinese Academy of Sciences , Hefei , Anhui 230031 , China
- University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Wei Tong
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Condition, High Magnetic Field Laboratory (HMFL) , Chinese Academy of Sciences , Hefei , Anhui 230031 , China
| | - Fapei Zhang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Condition, High Magnetic Field Laboratory (HMFL) , Chinese Academy of Sciences , Hefei , Anhui 230031 , China
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11
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Navamani K, Pati SK, Senthilkumar K. Effect of site energy fluctuation on charge transport in disordered organic molecules. J Chem Phys 2019; 151:224301. [PMID: 31837669 DOI: 10.1063/1.5122695] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Effect of dynamics of site energy disorder on charge transport in organic molecular semiconductors is not yet well-established. In order to study the relationship between the dynamics of site energy disorder and charge transport, we have performed a multiscale study on dialkyl substituted thienothiophene capped benzobisthiazole (BDHTT-BBT) and methyl-substituted dicyanovinyl-capped quinquethiophene (DCV5T-Me) molecular solids. In this study, we explore the structural dynamics and correlated charge transport by electronic structure calculations, molecular dynamics, and kinetic Monte-Carlo simulations. We have also proposed the differential entropy dependent diffusion and charge density equations to study the electric field drifted diffusion property and carrier density. In this investigation, we have addressed the transformation mechanism from dynamic to static disorder in the extended stacked molecular units. Here, the decrease in the charge transfer rate due to site energy fluctuations reveals the dispersion transport along the extended π-stacked molecules. Furthermore, the calculated current density for a different set of site energy difference values shows the validity and the limitations of the Einstein relation. Based on the calculated ideality factor, we have classified the charge transport in these molecules as either the Langevin or the Shockley-Read-Hall type mechanism. Through the calculated mobility, current density, and ideality factor analysis, we categorize the applicability of molecules of interest for photovoltaic or light emitting diode applications.
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Affiliation(s)
- K Navamani
- Theoretical Sciences Unit, School of Advanced Materials (SAMat), Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560064, India
| | - Swapan K Pati
- Theoretical Sciences Unit, School of Advanced Materials (SAMat), Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560064, India
| | - K Senthilkumar
- Department of Physics, Bharathiar University, Coimbatore 641046, India
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12
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Yang Y, Feng S, Li Z, Li T, Xiong Y, Cao L, Gao X. Unexpected Outstanding Room Temperature Spin Transport Verified in Organic-Inorganic Hybrid Perovskite Film. J Phys Chem Lett 2019; 10:4422-4428. [PMID: 31318215 DOI: 10.1021/acs.jpclett.9b01793] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Fundamental understanding on the spin transport properties of semiconducting organic-inorganic hybrid perovskites (OIHP) is of great importance for advancing their applications for spin-optoelectronic devices. Herein, the study of spin-pumping induced inverse spin Hall effect in Ni80Fe20(Py)/CH3NH3PbCl3-xIx/Pt trilayers with different OIHP spacer thicknesses concludes the spin diffusion length in CH3NH3PbCl3-xIx as large as 61 ± 7 nm at room temperature. In addition, spin-valves with a structure of Ni80Fe20(Py)/CH3NH3PbCl3-xIx/AlOx/Co was fabricated as well. Using a ∼160 nm-thick CH3NH3PbCl3-xIx spacer, the present spin valve exhibits a positive magnetoresistance (MR) of 0.57% at 10 K. Thus, the present spin related results demonstrate that electrical spin-polarized carrier injection, transport, and detection, which are essential in spintronic devices, can be successfully established in OIHP films. The outstanding spin transport in the present CH3NH3PbCl3-xIx should be owing to its highly out-of-plane oriented crystalline texture and Rashba spin splitting at domain boundaries between crystallographic orientations. These results demonstrate OIHP as very attractive materials for spintronics.
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Affiliation(s)
- Yingguo Yang
- Shanghai Synchrotron Radiation Facility(SSRF), Zhangjiang Lab. , Shanghai Advanced Research Institute, Chinese Academy of Sciences , 239 Zhangheng Road , Shanghai 201204 , China
- University of Chinese Academy of Sciences , Beijing 100049 , China
- Shanghai Institute of Applied Physics , Chinese Academy of Sciences, 2019 Jialuo Road , Shanghai 201800 , China
| | - Shanglei Feng
- Shanghai Synchrotron Radiation Facility(SSRF), Zhangjiang Lab. , Shanghai Advanced Research Institute, Chinese Academy of Sciences , 239 Zhangheng Road , Shanghai 201204 , China
- University of Chinese Academy of Sciences , Beijing 100049 , China
- Shanghai Institute of Applied Physics , Chinese Academy of Sciences, 2019 Jialuo Road , Shanghai 201800 , China
| | - Zhihao Li
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions , High Magnetic Field Laboratory, Chinese Academy of Sciences , Hefei , Anhui 230031 , China
| | - Tian Li
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions , High Magnetic Field Laboratory, Chinese Academy of Sciences , Hefei , Anhui 230031 , China
| | - Yimin Xiong
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions , High Magnetic Field Laboratory, Chinese Academy of Sciences , Hefei , Anhui 230031 , China
| | - Liang Cao
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions , High Magnetic Field Laboratory, Chinese Academy of Sciences , Hefei , Anhui 230031 , China
| | - Xingyu Gao
- Shanghai Synchrotron Radiation Facility(SSRF), Zhangjiang Lab. , Shanghai Advanced Research Institute, Chinese Academy of Sciences , 239 Zhangheng Road , Shanghai 201204 , China
- University of Chinese Academy of Sciences , Beijing 100049 , China
- Shanghai Institute of Applied Physics , Chinese Academy of Sciences, 2019 Jialuo Road , Shanghai 201800 , China
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13
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Simonetti O, Giraudet L. Transport models in disordered organic semiconductors and their application to the simulation of thin‐film transistors. POLYM INT 2019. [DOI: 10.1002/pi.5768] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Olivier Simonetti
- Laboratoire de Recherche en Nanosciences (LRN) ‐ EA 4682Université de Reims Champagne Ardenne Reims Cedex France
| | - Louis Giraudet
- Laboratoire de Recherche en Nanosciences (LRN) ‐ EA 4682Université de Reims Champagne Ardenne Reims Cedex France
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14
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Engmann S, Barito AJ, Bittle EG, Giebink NC, Richter LJ, Gundlach DJ. Higher order effects in organic LEDs with sub-bandgap turn-on. Nat Commun 2019; 10:227. [PMID: 30651556 PMCID: PMC6335427 DOI: 10.1038/s41467-018-08075-z] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 12/14/2018] [Indexed: 11/08/2022] Open
Abstract
Spin-dependent nonlinear processes in organic materials such as singlet-fission and triplet-triplet annihilation could increase the performance for photovoltaics, detectors, and light emitting diodes. Rubrene/C60 light emitting diodes exhibit a distinct low voltage (half-bandgap) threshold for emission. Two origins for the low voltage turn-on have been proposed: (i) Auger assisted energy up-conversion, and (ii) triplet-triplet annihilation. We test these proposals by systematically altering the rubrene/C60 interface kinetics by introducing thin interlayers. Quantitative analysis of the unmodified rubrene/C60 device suggests that higher order processes can be ruled out as the origin of the sub-bandgap turn-on. Rather, band-to-band recombination is the most likely radiative recombination process. However, insertion of a bathocuproine layer yields a 3-fold increase in luminance compared to the unmodified device. This indicates that suppression of parasitic interface processes by judicious modification of the interface allows a triplet-triplet annihilation channel to be observed.
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Affiliation(s)
- Sebastian Engmann
- Theiss Research, 7411 Eads Avenue, La Jolla, CA, 92037, USA.
- Nanoscale Device Characterization Division, National Institute of Standards and Technology, 101 Bureau Drive, Gaithersburg, MD, 20899, USA.
| | - Adam J Barito
- Nanoscale Device Characterization Division, National Institute of Standards and Technology, 101 Bureau Drive, Gaithersburg, MD, 20899, USA
| | - Emily G Bittle
- Nanoscale Device Characterization Division, National Institute of Standards and Technology, 101 Bureau Drive, Gaithersburg, MD, 20899, USA
| | - Noel C Giebink
- Department of Electrical Engineering, The Pennsylvania State University, Electrical Engineering West, State College, PA, 16801, USA
| | - Lee J Richter
- Materials Science and Engineering Division, National Institute of Standards and Technology, 101 Bureau Drive, Gaithersburg, MD, 20899, USA
| | - David J Gundlach
- Nanoscale Device Characterization Division, National Institute of Standards and Technology, 101 Bureau Drive, Gaithersburg, MD, 20899, USA.
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15
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Novikov SV. Diffusion of a particle in the Gaussian random-energy landscape: Einstein relation and analytical properties of average velocity and diffusivity as functions of driving force. Phys Rev E 2018; 98:012128. [PMID: 30110742 DOI: 10.1103/physreve.98.012128] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Indexed: 11/07/2022]
Abstract
We demonstrate that the Einstein relation for the diffusion of a particle in the random-energy landscape with the Gaussian density of states is an exclusive one-dimensional property and does not hold in higher dimensions. We also consider the analytical properties of the particle velocity and diffusivity for the limit of weak driving force and establish a connection between these properties and dimensionality and spatial correlation of the random-energy landscape.
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Affiliation(s)
- S V Novikov
- A. N. Frumkin Institute of Physical Chemistry and Electrochemistry, Leninsky prosp. 31, 119071 Moscow, Russia and National Research University Higher School of Economics, Myasnitskaya Ulitsa 20, Moscow 101000, Russia
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16
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Navamani K, Samanta PK, Pati SK. Theoretical modeling of charge transport in triphenylamine–benzimidazole based organic solids for their application as host-materials in phosphorescent OLEDs. RSC Adv 2018; 8:30021-30039. [PMID: 35547290 PMCID: PMC9085285 DOI: 10.1039/c8ra03281e] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 08/18/2018] [Indexed: 11/21/2022] Open
Abstract
The dynamic disorder and electric field effects on charge transport in triphenylamine–benzimidazole based molecular solids have been investigated using electronic structure calculations, molecular dynamics and Monte-Carlo simulations. During the charge propagation, the energy loss of the carrier in each hopping step is monitored by Monte-Carlo simulation. We derive a survival probability correlated momentum–energy distribution for drift-diffusion analysis and we demonstrate the dispersion initiated charge trapping mechanism which is indeed ideal for light emission efficiency via recombination. In the present model, the proposed carrier drift energy–current density expression and Shockley diode current density equation are used to study the current density–voltage characteristics; accordingly the ideality factor (∼1.8–2.0) dictates the deviation of Einstein's classical diffusion–mobility relation (where the ideality factor is unity). The dual mechanism of electric field assisted site energy gap on coherent-like transport and the electric field stretched dispersion on recombination are observed in tris(3′-(1-phenyl-1H-benzimidazole-2-yl)biphenyl-4-yl)amine (TBBI) and tris(4′-(1-phenyl-1H-benzimidazole-2-yl)biphenyl-4-yl)amine (TIBN) molecular systems, which can be used as host materials in organic light emitting diodes (OLEDs). We find the transport going from coherent to incoherent, due to the conversion mechanism of dynamic to static disorder. This can also be a controlled by applied electric field. By adjusting the applied electric field, film thickness and changing the π-stacked molecular aggregation via substitutions, one can fix the dispersive parameter and accordingly calculate the charge transport properties to design efficient host-materials for photovoltaic and light emitting diode devices. Dynamic disorder and electric field affect the charge (hole and electron) transport in host-materials for OLEDs.![]()
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Affiliation(s)
- K. Navamani
- School of Advanced Materials (SAMat)
- Theoretical Sciences Unit
- Jawaharlal Nehru Centre for Advanced Scientific Research
- Bangalore 560064
- India
| | - P. K. Samanta
- School of Advanced Materials (SAMat)
- Theoretical Sciences Unit
- Jawaharlal Nehru Centre for Advanced Scientific Research
- Bangalore 560064
- India
| | - S. K. Pati
- School of Advanced Materials (SAMat)
- Theoretical Sciences Unit
- Jawaharlal Nehru Centre for Advanced Scientific Research
- Bangalore 560064
- India
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17
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Wagenpfahl A. Mobility dependent recombination models for organic solar cells. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:373001. [PMID: 28612756 DOI: 10.1088/1361-648x/aa7952] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Modern solar cell technologies are driven by the effort to enhance power conversion efficiencies. A main mechanism limiting power conversion efficiencies is charge carrier recombination which is a direct function of the encounter probability of both recombination partners. In inorganic solar cells with rather high charge carrier mobilities, charge carrier recombination is often dominated by energetic states which subsequently trap both recombination partners for recombination. Free charge carriers move fast enough for Coulomb attraction to be irrelevant for the encounter probability. Thus, charge carrier recombination is independent of charge carrier mobilities. In organic semiconductors charge carrier mobilities are much lower. Therefore, electrons and holes have more time react to mutual Coulomb-forces. This results in the strong charge carrier mobility dependencies of the observed charge carrier recombination rates. In 1903 Paul Langevin published a fundamental model to describe the recombination of ions in gas-phase or aqueous solutions, known today as Langevin recombination. During the last decades this model was used to interpret and model recombination in organic semiconductors. However, certain experiments especially with bulk-heterojunction solar cells reveal much lower recombination rates than predicted by Langevin. In search of an explanation, many material and device properties such as morphology and energetic properties have been examined in order to extend the validity of the Langevin model. A key argument for most of these extended models is, that electron and hole must find each other at a mutual spatial location. This encounter may be limited for instance by trapping of charges in trap states, by selective electrodes separating electrons and holes, or simply by the morphology of the involved semiconductors, making it impossible for electrons and holes to recombine at high rates. In this review, we discuss the development of mobility limited recombination models from the early Langevin theory to state-of-the art models for charge carrier recombination in organic solar cells.
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18
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Wang M, Yim WL, Liao P, Shen Y. Temperature Dependent Characteristics of Perovskite Solar Cells. ChemistrySelect 2017. [DOI: 10.1002/slct.201700776] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Mingkui Wang
- Wuhan National Laboratory for Optoelectronics; Huazhong University of Science and Technology; Luoyu Road 1037 Wuhan 430074 China
| | - Wai-Leung Yim
- Institute of High Performance Computing; Agency for Science; Technology and Research; 1 Fusionopolis Way, No. 16-16 Connexis Singapore 138632
| | - Peizhe Liao
- Wuhan National Laboratory for Optoelectronics; Huazhong University of Science and Technology; Luoyu Road 1037 Wuhan 430074 China
| | - Yan Shen
- Wuhan National Laboratory for Optoelectronics; Huazhong University of Science and Technology; Luoyu Road 1037 Wuhan 430074 China
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19
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Groves C. Simulating charge transport in organic semiconductors and devices: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:026502. [PMID: 27991440 DOI: 10.1088/1361-6633/80/2/026502] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Charge transport simulation can be a valuable tool to better understand, optimise and design organic transistors (OTFTs), photovoltaics (OPVs), and light-emitting diodes (OLEDs). This review presents an overview of common charge transport and device models; namely drift-diffusion, master equation, mesoscale kinetic Monte Carlo and quantum chemical Monte Carlo, and a discussion of the relative merits of each. This is followed by a review of the application of these models as applied to charge transport in organic semiconductors and devices, highlighting in particular the insights made possible by modelling. The review concludes with an outlook for charge transport modelling in organic electronics.
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Affiliation(s)
- C Groves
- Durham University, School of Engineering and Computing Sciences, South Road, Durham, DH1 3LE, UK
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20
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van der Kaap NJ, Koster LJA. Charge carrier thermalization in organic diodes. Sci Rep 2016; 6:19794. [PMID: 26791095 PMCID: PMC4726152 DOI: 10.1038/srep19794] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 12/18/2015] [Indexed: 11/09/2022] Open
Abstract
Charge carrier mobilities of organic semiconductors are often characterized using steady-state measurements of space charge limited diodes. These measurements assume that charge carriers are in a steady-state equilibrium. In reality, however, energetically hot carriers are introduces by photo-excitation and injection into highly energetic sites from the electrodes. These carriers perturb the equilibrium density of occupied states, and therefore change the overall charge transport properties. In this paper, we look into the effect of energetically hot carriers on the charge transport in organic semiconductors using steady state kinetic Monte Carlo simulations. For injected hot carriers in a typical organic semiconductor, rapid energetic relaxation occurs in the order of tens of nanoseconds, which is much faster than the typical transit time of a charge carrier throught the device. Furthermore, we investigate the impact of photo-generated carriers on the steady-state mobility. For a typical organic voltaic material, an increase in mobility of a factor of 1.1 is found. Therefore, we conclude that the impact of energetically hot carriers on normal device operation is limited.
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Affiliation(s)
- N J van der Kaap
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
| | - L J A Koster
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
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21
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Li D, Cui J, Zhang H, Li H, Wang M, Shen Y. Effect of Hole Transport Layer in Planar Inverted Perovskite Solar Cells. CHEM LETT 2016. [DOI: 10.1246/cl.150888] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Dan Li
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology
| | - Jin Cui
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology
| | - Hua Zhang
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology
| | - Hao Li
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology
| | - Mingkui Wang
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology
| | - Yan Shen
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology
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22
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Navamani K, Senthilkumar K. Forth-back oscillated charge carrier motion in dynamically disordered hexathienocoronene molecules: a theoretical study. Phys Chem Chem Phys 2015; 17:17729-38. [PMID: 26080732 DOI: 10.1039/c5cp02189h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Electronic structure calculations were performed to investigate the charge transport properties of hexathienocoronene (HTC) based molecules. The effective displacement of the charge carrier along the π-orbital of nearby molecules is calculated by monitoring the forth and back oscillations of the charge carrier through kinetic Monte Carlo simulation. The charge transport parameters such as charge transfer rate, mobility, hopping conductivity, localized charge density, time average effective mass and degeneracy pressure are calculated and used to study the charge transport mechanism in the studied molecules. The existence of degeneracy levels facilitates the charge transfer and is analyzed through degeneracy pressure. Theoretical results show that the site energy difference in the dynamically disordered system controls the forth-back oscillation of charge carrier and facilitates the unidirectional charge transport mechanism along the sequential localized sites. The ethyl substituted HTC has good hole and electron hopping conductivity of 415 and 894 S cm(-1), respectively, whereas unsubstituted HTC has the small hole mobility of 0.06 cm(2) V(-1) s(-1) which is due to large average effective mass of 1.42 × 10(-28) kg.
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Affiliation(s)
- K Navamani
- Department of Physics, Bharathiar University, Coimbatore-641 046, India.
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23
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Wetzelaer GJAH, Scheepers M, Sempere AM, Momblona C, Ávila J, Bolink HJ. Trap-assisted non-radiative recombination in organic-inorganic perovskite solar cells. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2015; 27:1837-1841. [PMID: 25648930 DOI: 10.1002/adma.201405372] [Citation(s) in RCA: 217] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Revised: 12/23/2014] [Indexed: 05/28/2023]
Affiliation(s)
- Gert-Jan A H Wetzelaer
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
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24
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Khan MA, Jiu-Xun S, Ke J, Ling-Cang C, Qiang W. Consistent double Gaussian model with non-symmetric potential barriers at contacts for organic diodes. RSC Adv 2015. [DOI: 10.1039/c4ra02353f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A transport model with double Gaussian density of state (DOS) for organic semiconductors is proposed, with one Gaussian DOS for free carriers and one for trapped carriers.
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Affiliation(s)
- Muhammad Ammar Khan
- School of Physical Electronics
- University of Electronic Science and Technology
- Chengdu 610054
- China
| | - Sun Jiu-Xun
- School of Physical Electronics
- University of Electronic Science and Technology
- Chengdu 610054
- China
- Laboratory for Shock Wave and Detonation Physics Research
| | - Jin Ke
- Laboratory for Shock Wave and Detonation Physics Research
- Southwest Institute of Fluid Physics
- Mianyang 621900
- China
| | - Cai Ling-Cang
- Laboratory for Shock Wave and Detonation Physics Research
- Southwest Institute of Fluid Physics
- Mianyang 621900
- China
| | - Wu Qiang
- Laboratory for Shock Wave and Detonation Physics Research
- Southwest Institute of Fluid Physics
- Mianyang 621900
- China
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25
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Affiliation(s)
- Nir Tessler
- The Sarah and Moshe Zisapel Nanoelectronic Center; Electrical Engineering Deparment, Technion Israel Institute of Technology; Haifa 32000 Israel
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26
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Amarasinghe Vithanage D, Devižis A, Abramavičius V, Infahsaeng Y, Abramavičius D, MacKenzie RCI, Keivanidis PE, Yartsev A, Hertel D, Nelson J, Sundström V, Gulbinas V. Visualizing charge separation in bulk heterojunction organic solar cells. Nat Commun 2014; 4:2334. [PMID: 23945881 DOI: 10.1038/ncomms3334] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 07/22/2013] [Indexed: 11/09/2022] Open
Abstract
Solar cells based on conjugated polymer and fullerene blends have been developed as a low-cost alternative to silicon. For efficient solar cells, electron-hole pairs must separate into free mobile charges that can be extracted in high yield. We still lack good understanding of how, why and when carriers separate against the Coulomb attraction. Here we visualize the charge separation process in bulk heterojunction solar cells by directly measuring charge carrier drift in a polymer:fullerene blend with ultrafast time resolution. We show that initially only closely separated (<1 nm) charge pairs are created and they separate by several nanometres during the first several picoseconds. Charge pairs overcome Coulomb attraction and form free carriers on a subnanosecond time scale. Numerical simulations complementing the experimental data show that fast three-dimensional charge diffusion within an energetically disordered medium, increasing the entropy of the system, is sufficient to drive the charge separation process.
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27
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Yao Y, Yang W, Zhao Y. Exciton dissociation in the presence of phonons: A reduced hierarchy equations of motion approach. J Chem Phys 2014; 140:104113. [DOI: 10.1063/1.4867418] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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28
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Adachi T, Vogelsang J, Lupton JM. Unraveling the Electronic Heterogeneity of Charge Traps in Conjugated Polymers by Single-Molecule Spectroscopy. J Phys Chem Lett 2014; 5:573-577. [PMID: 26276611 DOI: 10.1021/jz402621y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Charge trapping is taken for granted in modeling the characteristics of organic semiconductor devices, but very few techniques actually exist to spectroscopically pinpoint trap states. For example, trap levels are often assumed to be discrete in energy. Using the well-known keto defect in polyfluorene as a model, we demonstrate how single-molecule spectroscopy can directly track the formation of charge and exciton traps in conjugated polymers in real time, providing crucial information on the energetic distribution of trap sites relative to the polymer optical gap. Charge traps with universal spectral fingerprints scatter by almost 1 eV in depth, implying that substantial heterogeneity must be taken into account when modeling devices.
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Affiliation(s)
- Takuji Adachi
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - Jan Vogelsang
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - John M Lupton
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
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29
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30
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de Bruyn P, van Rest AHP, Wetzelaer GAH, de Leeuw DM, Blom PWM. Diffusion-limited current in organic metal-insulator-metal diodes. PHYSICAL REVIEW LETTERS 2013; 111:186801. [PMID: 24237546 DOI: 10.1103/physrevlett.111.186801] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 08/15/2013] [Indexed: 06/02/2023]
Abstract
An analytical expression for the diffusion current in organic metal-insulator-metal diodes is derived. The derivation is based on the classical diffusion theory of Schottky, with adaptations to account for the absence of doping, a built-in voltage due to asymmetric contacts, and band bending at the Ohmic contact. The commonly observed deviation of the ideality factor from unity (~1.2) is characteristic of diffusion-limited currents in undoped organic semiconductors. Summing with the classical space-charge limited current provides a full analytic description of the current as a function of voltage, temperature and layer thickness.
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Affiliation(s)
- P de Bruyn
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, Netherlands and Dutch Polymer Institute, Post Office Box 902, 5600 AX Eindhoven, Netherlands
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31
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Yao Y, Si W, Yang W, Wu CQ. Charge transport in organic semiconductors: From incoherent to coherent. CHINESE SCIENCE BULLETIN 2013. [DOI: 10.1007/s11434-013-5931-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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32
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Liu C, Li Y, Lee MV, Kumatani A, Tsukagoshi K. Self-assembly of semiconductor/insulator interfaces in one-step spin-coating: a versatile approach for organic field-effect transistors. Phys Chem Chem Phys 2013; 15:7917-33. [DOI: 10.1039/c3cp44715d] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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33
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Chen G, Sasabe H, Wang Z, Wang X, Hong Z, Kido J, Yang Y. Solution-processed organic photovoltaic cells based on a squaraine dye. Phys Chem Chem Phys 2012; 14:14661-6. [PMID: 23032516 DOI: 10.1039/c2cp42445b] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this work, 2,4-bis[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl] squaraine (SQ) was systematically studied as an electron donor in solution processed photovoltaic cells, showing power conversion efficiency of >4.0% under AM1.5G 1 sun illumination at room temperature. Low mobilities were found to limit charge transport in the bulk heterojunctions. Efficiency was thus improved to 5.1% at 80 °C mainly due to improvement of photocurrent extraction. We also demonstrated that the SQ compound synthesized via a simple method has high purity, and thus can be used in photovoltaic cells without further purification. Our results suggest the huge potential of SQ and its analogs in organic photovoltaic applications.
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Affiliation(s)
- Guo Chen
- Department of Organic Device Engineering, Graduate School of Science and Engineering, Research Center for Organic Electronics (ROEL), Yamagata University, Yonezawa, Yamagata, Japan
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34
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Yao Y, Si W, Hou X, Wu CQ. Monte Carlo simulation based on dynamic disorder model in organic semiconductors: From coherent to incoherent transport. J Chem Phys 2012; 136:234106. [DOI: 10.1063/1.4729310] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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