1
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Liu M, Tang G, Liu Y, Jiang FL. Ligand Exchange of Quantum Dots: A Thermodynamic Perspective. J Phys Chem Lett 2024; 15:1975-1984. [PMID: 38346356 DOI: 10.1021/acs.jpclett.3c03413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Colloidal quantum dots (QDs) consist of an inorganic core and organic surface ligands. Surface ligands play a dominant role in maintaining the colloidal stability of QDs and passivating the surface defects of QDs. However, the original ligands introduced in the synthetic process of QDs cannot meet the requirements for diverse applications; therefore, ligand exchanges with functional ligands are mandatory. Understanding the ligand exchange process requires a comprehensive combination of the concepts and techniques of surface chemistry. In this Perspective, the ligand exchange process is discussed in detail. Specifically, we elaborate on the thermodynamics that can reveal the feasibility and mechanism of ligand exchange. It depicts a critical physical picture of the surface of QDs along with the following ligand exchange.
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Affiliation(s)
- Meng Liu
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, P. R. China
| | - Ge Tang
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, P. R. China
| | - Yi Liu
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, P. R. China
- State Key Laboratory of Separation Membranes and Membrane Processes, School of Chemistry, Tiangong University, Tianjin 300387, P. R. China
| | - Feng-Lei Jiang
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, P. R. China
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2
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Lee J, Kim B, Kim C, Lee MH, Kozakci I, Cho S, Kim B, Lee SY, Kim J, Oh J, Lee JY. Unlocking the Potential of Colloidal Quantum Dot/Organic Hybrid Solar Cells: Band Tunable Interfacial Layer Approach. ACS APPLIED MATERIALS & INTERFACES 2023; 15:39408-39416. [PMID: 37555937 DOI: 10.1021/acsami.3c08419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/10/2023]
Abstract
Hybrid colloidal quantum dot (CQD)/organic architectures are promising candidates for emerging optoelectronic devices having high performance and inexpensive fabrication. For unlocking the potential of CQD/organic hybrid devices, enhancing charge extraction properties at electron transport layer (ETL)/CQD interfaces is crucial. Hence, we carefully adjust the interface properties between the ETL and CQD layer by incorporating an interfacial layer for the ETL (EIL) using several types of cinnamic acid ligands. The EIL having a cascading band offset (ΔEC) between the ETL and CQD layer suppresses the potential barrier and the local charge accumulation at ETL/CQD interfaces, thereby reducing the bimolecular recombination. An optimal EIL effectively expands the depletion region that facilitates charge extraction between the ETL and CQD layer while preventing the formation of shallow traps. Representative devices with an EIL exhibit a maximum power conversion efficiency of 14.01% and retain over 80% of initial performances after 300 h under continuous maximum power point operation.
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Affiliation(s)
- Jihyung Lee
- School of Electrical Engineering (EE), Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Byeongsu Kim
- School of Electrical Engineering (EE), Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Changjo Kim
- Information and Electronics Research Institute, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Min-Ho Lee
- School of Electrical Engineering (EE), Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Irem Kozakci
- School of Electrical Engineering (EE), Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Sungjun Cho
- School of Electrical Engineering (EE), Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Beomil Kim
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Sang Yeon Lee
- Information and Electronics Research Institute, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Junho Kim
- School of Electrical Engineering (EE), Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Jihun Oh
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Jung-Yong Lee
- School of Electrical Engineering (EE), Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
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3
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Martinez M, Nolen MA, Pompetti NF, Richter LJ, Farberow CA, Johnson JC, Beard MC. Controlling Electronic Coupling of Acene Chromophores on Quantum Dot Surfaces through Variable-Concentration Ligand Exchange. ACS NANO 2023; 17:14916-14929. [PMID: 37494884 PMCID: PMC10416565 DOI: 10.1021/acsnano.3c03498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 07/18/2023] [Indexed: 07/28/2023]
Abstract
Controlling the binding of functional organic molecules on quantum dot (QD) surfaces and the resulting ligand/QD interfacial structure determines the resulting organic-inorganic hybrid behavior. In this study, we vary the binding of tetracenedicarboxylate ligands bound to PbS QDs cast in thin films by performing solid-state ligand exchange of as-produced bound oleate ligands. We employ comprehensive Fourier-transform infrared (FTIR) analysis coupled with ultraviolet-visible (UV-vis) spectrophotometric measurements, transient absorption, and Density Functional Theory (DFT) simulations to study the QD/ligand surface structure and resulting optoelectronic properties. We find that there are three primary QD/diacid structures, each with a distinct binding mode dictated by the QD-ligand and ligand-ligand intermolecular and steric interactions. They can be accessed nearly independently of one another via different input ligand concentrations. Low concentrations produce mixed oleate/tetracene ligand structures where the tetracene carboxylates tilt toward QD surfaces. Intermediate concentrations produce mixed oleate/tetracene ligand structures with ligand-ligand interactions through intramolecular hydrogen bonding with the ligands perpendicular to the QD surface and weaker QD/ligand electronic interactions. High concentrations result in full ligand exchange, and the ligands tilt toward the surface while the QD film compacts. When the tetracene ligands tilt or lie flat on the QD surface, the benzene ring π-system interacts strongly with the p-orbitals at the PbS surface and produces strong QD-ligand interactions evidenced through QD/ligand state mixing, with a coupling energy of ≈700 meV.
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Affiliation(s)
- Marissa
S. Martinez
- Chemistry
& Nanoscience Center, National Renewable
Energy Laboratory, Golden, Colorado 80401, United States
| | - Michelle A. Nolen
- Department
of Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Nicholas F. Pompetti
- Department
of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Lee J. Richter
- Materials
Science and Engineering Division, National
Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Carrie A. Farberow
- Catalytic
Carbon Transformation & Scale-Up Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Justin C. Johnson
- Chemistry
& Nanoscience Center, National Renewable
Energy Laboratory, Golden, Colorado 80401, United States
| | - Matthew C. Beard
- Chemistry
& Nanoscience Center, National Renewable
Energy Laboratory, Golden, Colorado 80401, United States
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4
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Zhao G, Ma W, Yu S, Zhang J, Wu K. Orbital Mixing between Colloidal Quantum Dots and Surface-Bound Molecules. J Phys Chem Lett 2022; 13:11892-11898. [PMID: 36524775 DOI: 10.1021/acs.jpclett.2c03538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Orbital mixing is paramount to chemistry as it plays a central role in bond formation. It is also important for technologies such as molecular doping of polymers, where the concept of fractional charge transfer is essentially orbital mixing between dopants and hosts. Likewise, it would be both fundamentally interesting and technologically relevant to investigate orbital mixing in emerging hybrid materials containing both inorganic and organic moieties. Here we report experimental observation of orbital mixing between valence band levels of strongly confined PbS quantum dots (QDs) and lowest unoccupied molecular levels of surface-bound high-electron affinity molecules (F4TCNQ), manifested as both an absorption blue-shift of PbS and the emergence of visible and infrared signatures of the fractional charge-transfer species of F4TCNQ. The degree of mixing can be controlled by varying the QD size or by varying the molecule/QD ratio for a specific QD size and can be quantitatively reproduced by a nondegenerate, two-level perturbation model.
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Affiliation(s)
- Guohui Zhao
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning116023, China
- University of Chinese Academy of Sciences, Beijing100049, China
| | - Wenkai Ma
- School of Optical and Electronic Information, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei430074, China
| | - Shuwen Yu
- Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning116023, China
| | - Jianbing Zhang
- School of Optical and Electronic Information, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei430074, China
| | - Kaifeng Wu
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning116023, China
- University of Chinese Academy of Sciences, Beijing100049, China
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5
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Raulerson EK, Cadena DM, Jabed MA, Wight CD, Lee I, Wagner HR, Brewster JT, Iverson BL, Kilina S, Roberts ST. Using Spectator Ligands to Enhance Nanocrystal-to-Molecule Electron Transfer. J Phys Chem Lett 2022; 13:1416-1423. [PMID: 35119280 DOI: 10.1021/acs.jpclett.1c03825] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Semiconductor nanocrystals (NCs) have emerged as promising photocatalysts. However, NCs are often functionalized with complex ligand shells that contain not only charge acceptors but also other "spectator ligands" that control NC solubility and affinity for target reactants. Here, we show that spectator ligands are not passive observers of photoinduced charge transfer but rather play an active role in this process. We find the rate of electron transfer from quantum-confined PbS NCs to perylenediimide acceptors can be varied by over a factor of 4 simply by coordinating cinnamate ligands with distinct dipole moments to NC surfaces. Theoretical calculations indicate this rate variation stems from both ligand-induced changes in the free energy for charge transfer and electrostatic interactions that alter perylenediimide electron acceptor orientation on NC surfaces. Our work shows NC-to-molecule charge transfer can be fine-tuned through ligand shell design, giving researchers an additional handle for enhancing NC photocatalysis.
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Affiliation(s)
- Emily K Raulerson
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Danielle M Cadena
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Mohammed A Jabed
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58108, United States
| | - Christopher D Wight
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Inki Lee
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Holden R Wagner
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - James T Brewster
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Brent L Iverson
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Svetlana Kilina
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58108, United States
| | - Sean T Roberts
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
- Center for Dynamics and Control of Materials, The University of Texas at Austin, Austin, Texas 78712, United States
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6
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Giansante C. Surface Chemistry Impact on the Light Absorption by Colloidal Quantum Dots. Chemistry 2021; 27:14359-14369. [PMID: 34351015 PMCID: PMC8596982 DOI: 10.1002/chem.202102168] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Indexed: 11/10/2022]
Abstract
At the size scale at which quantum confinement effects arise in inorganic semiconductors, the materials' surface-to-volume ratio is intrinsically high. This consideration sets surface chemistry as a powerful tool to exert further control on the electronic structure of the inorganic semiconductors. Among the materials that experience the quantum confinement regime, those prepared via colloidal synthetic procedures (the colloidal quantum dots - and wires and wells, too -) are prone to undergo surface reactions in the solution phase and thus represent an ideal framework to study the ensemble impact of surface chemistry on the materials' electronic structure. It is here discussed such an impact at the ground state by using the absorption spectrum of the colloidal quantum dots as a descriptor. The experiments show that the chemical species (the ligands) at the colloidal quantum dot surface induce changes to the optical band gap, the absorption coefficient at all wavelengths, and the ionization potential. These evidences point to a description of the colloidal quantum dot (the ligand/core adduct) as an indecomposable species, in which the orbitals localized on the ligands and the core mix in each other's electric field. This description goes beyond conventional models that conceive the ligands on the basis of pure electrostatic arguments (i. e., either as a dielectric shell or as electric dipoles) or as a mere potential energy barrier at the core boundaries.
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Affiliation(s)
- Carlo Giansante
- Carlo Giansante CNR NANOTEC, Istituto di NanotecnologiaVia Monteroni73100LecceItaly
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7
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Hartley CL, Kessler ML, Dempsey JL. Molecular-Level Insight into Semiconductor Nanocrystal Surfaces. J Am Chem Soc 2021; 143:1251-1266. [PMID: 33442974 DOI: 10.1021/jacs.0c10658] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Semiconductor nanocrystals exhibit attractive photophysical properties for use in a variety of applications. Advancing the efficiency of nanocrystal-based devices requires a deep understanding of the physical defects and electronic states that trap charge carriers. Many of these states reside at the nanocrystal surface, which acts as an interface between the semiconductor lattice and the molecular capping ligands. While a detailed structural and electronic understanding of the surface is required to optimize nanocrystal properties, these materials are at a technical disadvantage: unlike molecular structures, semiconductor nanocrystals lack a specific chemical formula and generally must be characterized as heterogeneous ensembles. Therefore, in order for the field to improve current nanocrystal-based technologies, a creative approach to gaining a "molecular-level" picture of nanocrystal surfaces is required. To this end, an expansive toolbox of experimental and computational techniques has emerged in recent years. In this Perspective, we critically evaluate the insight into surface structure and reactivity that can be gained from each of these techniques and demonstrate how their strategic combination is already advancing our molecular-level understanding of nanocrystal surface chemistry.
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Affiliation(s)
- Carolyn L Hartley
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, United States
| | - Melody L Kessler
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, United States
| | - Jillian L Dempsey
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, United States
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8
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Asaduzzaman A, Runge K, Deymier P, Muralidharan K. Effect of Ligand Adsorption on the Electronic Properties of the PbS(100) Surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:13312-13319. [PMID: 33112623 DOI: 10.1021/acs.langmuir.0c02425] [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
A first-principles density functional theory calculation was carried out to study the adsorption of acetic acid, methyl amine, methanethiol, and hydrogen iodide on the (100) surface of PbS. All four ligands are common capping agents used in colloidal PbS quantum dot-based photovoltaics. Interestingly, among the considered adsorbates, dissociative adsorption was energetically preferred for hydrogen iodide, while associative adsorption was favorable for the rest. Associative adsorption was driven by strong interactions between the electronegative elements (Y) in the respective ligands and the Pb surface atoms via Pb 6p-Y np bond hybridization (n represents the valence quantum number of the respective electronegative elements). Importantly, the adsorption of ligands altered the work function of PbS, with contrasting trends for associative (decrease in the work function) versus dissociative (increase in the work function) adsorption. The changes in the work function correlates well with a corresponding shift in the 5d level of surface Pb atoms. Other important observations include variations in the work function that linearly change with increasing the surface coverage of adsorbed ligands as well as with the strength of the adsorption of ligands.
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Affiliation(s)
- Abu Asaduzzaman
- School of Science, Engineering and Technology, Pennsylvania State University - Harrisburg, Middletown, Pennsylvania 17057, United States
| | - Keith Runge
- Materials Science and Engineering, University of Arizona, Tucson, Arizona 85721, United States
| | - Pierre Deymier
- Materials Science and Engineering, University of Arizona, Tucson, Arizona 85721, United States
| | - Krishna Muralidharan
- Materials Science and Engineering, University of Arizona, Tucson, Arizona 85721, United States
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9
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Derr JB, Tamayo J, Clark JA, Morales M, Mayther MF, Espinoza EM, Rybicka-Jasińska K, Vullev VI. Multifaceted aspects of charge transfer. Phys Chem Chem Phys 2020; 22:21583-21629. [PMID: 32785306 PMCID: PMC7544685 DOI: 10.1039/d0cp01556c] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Charge transfer and charge transport are by far among the most important processes for sustaining life on Earth and for making our modern ways of living possible. Involving multiple electron-transfer steps, photosynthesis and cellular respiration have been principally responsible for managing the energy flow in the biosphere of our planet since the Great Oxygen Event. It is impossible to imagine living organisms without charge transport mediated by ion channels, or electron and proton transfer mediated by redox enzymes. Concurrently, transfer and transport of electrons and holes drive the functionalities of electronic and photonic devices that are intricate for our lives. While fueling advances in engineering, charge-transfer science has established itself as an important independent field, originating from physical chemistry and chemical physics, focusing on paradigms from biology, and gaining momentum from solar-energy research. Here, we review the fundamental concepts of charge transfer, and outline its core role in a broad range of unrelated fields, such as medicine, environmental science, catalysis, electronics and photonics. The ubiquitous nature of dipoles, for example, sets demands on deepening the understanding of how localized electric fields affect charge transfer. Charge-transfer electrets, thus, prove important for advancing the field and for interfacing fundamental science with engineering. Synergy between the vastly different aspects of charge-transfer science sets the stage for the broad global impacts that the advances in this field have.
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Affiliation(s)
- James B Derr
- Department of Biochemistry, University of California, Riverside, CA 92521, USA.
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10
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Abstract
Surfaces-and interfaces-are ubiquitous at the nanoscale. Their relevance to nanoscience and nanotechnology is therefore inherent. Colloidal inorganic nanocrystals (NCs), which can show more than a half of their atoms at the surface, are paradigmatic of the role of surfaces in determining materials' form and functions. Therefore, colloidal NCs may be regarded as soluble surfaces, allowing convenient study of ensemble structure and properties in the solution phase.Colloidal NCs commonly bear chemical species at their surface. Such species (generally referred to as ligands) are introduced already in the synthetic procedures and are added postsynthesis in surface chemistry modification (ligand exchange) reactions. Ligands (i) affect the reactivity and diffusion of the synthetic precursors, (ii) mediate NC interactions with the surroundings, and (iii) contribute to the overall electronic structure. In principle, a vast amount of ligands, as large as our imagination, could be used to coordinate the surface of colloidal NCs. In practice and despite the plethora of studies on NC surface chemistry, a relatively limited number of ligands have been explored. In addition, the importance of designing a set of ligands with tailored features (a ligand library), which may permit comprehensive discussion and explanation of the role of surfaces in the NC structure and properties, is often overlooked. Ligand libraries may also foster heuristic access to novel, unexpected observations.Here, the rational design of ligand libraries is discussed, suggesting that it may be a general method to advance knowledge on colloidal NCs and nanomaterials at large.First, a general ligand framework is introduced. The main subunits are identified: ligands are constituted by a binding group and a pendant moiety, bearing functional substituent groups. On this basis, ligand binding at the NC surface is discussed borrowing concepts from coordination chemistry. Dynamic equilibria at the NC surface are highlighted, revealing the compromise between forming and breaking bonds at interfaces and its intricate interplay with the surroundings. Tailoring of the ligand subunits may impart functions to the whole ligand, eventually transposable to the ligated NC.On these bases, it is shown how ligand design may be exploited to (i) exert control on the size and shape of the NCs, (ii) determine NCs' dispersibility in a solvent and affect their self-assembly, and (iii) tune the NCs' optical and electronic properties. These observations point to a description of colloidal NCs as un-decomposable species: ligands may be conceived as an integral part of the overall chemical and electronic structure of the colloidal NC and should not be considered as mere appendages that weakly perturb the inorganic core features.Finally, a perspective on the ligand library design is given. Function-oriented design of the ligand subunits is foreseen as an effective strategy to explore the chemical diversity space. High-throughput screening processes by using computation may represent a valuable tool for such an exploration. The whole ligand features, which depend on the subunits, can be implemented in the final NCs, providing feedback for refined design, toward a priori materials design. Ligand libraries can be fundamental to enabling colloidal NCs as reliable luminophores and (photo)catalysts.
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Affiliation(s)
- Carlo Giansante
- CNR NANOTEC, Istituto di Nanotecnologia, Via Monteroni, 73100 Lecce, Italy
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11
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Jia D, Chen J, Yu M, Liu J, Johansson EMJ, Hagfeldt A, Zhang X. Dual Passivation of CsPbI 3 Perovskite Nanocrystals with Amino Acid Ligands for Efficient Quantum Dot Solar Cells. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e2001772. [PMID: 32419275 DOI: 10.1002/smll.202001772] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 04/22/2020] [Accepted: 04/22/2020] [Indexed: 05/08/2023]
Abstract
Inorganic CsPbI3 perovskite quantum dot (PQD) receives increasing attention for the application in the new generation solar cells, but the defects on the surface of PQDs significantly affect the photovoltaic performance and stability of solar cells. Herein, the amino acids are used as dual-passivation ligands to passivate the surface defects of CsPbI3 PQDs using a facile single-step ligand exchange strategy. The PQD surface properties are investigated in depth by combining experimental studies and theoretical calculation approaches. The PQD solid films with amino acids as dual-passivation ligands on the PQD surface are thoroughly characterized using extensive techniques, which reveal that the glycine ligand can significantly improve defect passivation of PQDs and therefore diminish charge carrier recombination in the PQD solid. The power conversion efficiency (PCE) of the glycine-based PQD solar cell (PQDSC) is improved by 16.9% compared with that of the traditional PQDSC fabricated with Pb(NO3 )2 treating the PQD surface, owning to improved charge carrier extraction. Theoretical calculations are carried out to comprehensively understand the thermodynamic feasibility and favorable charge density distribution on the PQD surface with a dual-passivation ligand.
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Affiliation(s)
- Donglin Jia
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Jingxuan Chen
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Mei Yu
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Jianhua Liu
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Erik M J Johansson
- Department of Chemistry-Ångström, Physical Chemistry, Uppsala University, Uppsala, 75120, Sweden
| | - Anders Hagfeldt
- Laboratory of Photomolecular Science, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne, Station 6, Lausanne, CH-1015, Switzerland
| | - Xiaoliang Zhang
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
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12
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Lu H, Zhu X, Miller C, San Martin J, Chen X, Miller EM, Yan Y, Beard MC. Enhanced photoredox activity of CsPbBr3 nanocrystals by quantitative colloidal ligand exchange. J Chem Phys 2019; 151:204305. [DOI: 10.1063/1.5129261] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Haipeng Lu
- Chemistry and Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, USA
| | - Xiaolin Zhu
- Department of Chemistry and Biochemistry, San Diego State University, San Diego, California 92182, USA
| | - Collin Miller
- Department of Chemistry and Biochemistry, San Diego State University, San Diego, California 92182, USA
| | - Jovan San Martin
- Department of Chemistry and Biochemistry, San Diego State University, San Diego, California 92182, USA
| | - Xihan Chen
- Chemistry and Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, USA
| | - Elisa M. Miller
- Chemistry and Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, USA
| | - Yong Yan
- Department of Chemistry and Biochemistry, San Diego State University, San Diego, California 92182, USA
| | - Matthew C. Beard
- Chemistry and Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, USA
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13
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Zhou Q, Cho Y, Yang S, Weiss EA, Berkelbach TC, Darancet P. Large Band Edge Tunability in Colloidal Nanoplatelets. NANO LETTERS 2019; 19:7124-7129. [PMID: 31545615 DOI: 10.1021/acs.nanolett.9b02645] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We study the impact of organic surface ligands on the electronic structure and electronic band edge energies of quasi-two-dimensional (2D) colloidal cadmium selenide nanoplatelets (NPLs) using density functional theory. We show how control of the ligand and ligand-NPL interface dipoles results in large band edge energy shifts, over a range of 5 eV for common organic ligands with a minor effect on the NPL band gaps. Using a model self-energy to account for the dielectric contrast and an effective mass model of the excitons, we show that the band edge tunability of NPLs together with the strong dependence of the optical band gap on NPL thickness can lead to favorable photochemical and optoelectronic properties.
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Affiliation(s)
- Qunfei Zhou
- Materials Research Science and Engineering Center , Northwestern University , Evanston , Illinois 60208 , United States
- Center for Nanoscale Materials , Argonne National Laboratory , Argonne , Illinois 60439 , United States
| | - Yeongsu Cho
- Department of Chemistry and James Franck Institute , University of Chicago , Chicago , Illinois 60637 , United States
| | - Shenyuan Yang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors , Chinese Academy of Sciences , Beijing 100083 , China
- Center for Materials Science and Optoelectronics Engineering , University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Emily A Weiss
- Department of Chemistry and Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
| | - Timothy C Berkelbach
- Department of Chemistry , Columbia University , New York , New York 10027 , United States
- Center for Computational Quantum Physics , Flatiron Institute , New York , New York 10010 , United States
| | - Pierre Darancet
- Center for Nanoscale Materials , Argonne National Laboratory , Argonne , Illinois 60439 , United States
- Northwestern Argonne Institute of Science and Engineering , Evanston , Illinois 60208 , United States
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Giansante C. Enhancing light absorption by colloidal metal chalcogenide quantum dots via chalcogenol(ate) surface ligands. NANOSCALE 2019; 11:9478-9487. [PMID: 31045198 DOI: 10.1039/c9nr01785b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Chemical species at the surface (ligands) of colloidal inorganic semiconductor nanocrystals (QDs) markedly impact the optoelectronic properties of the resulting systems. Here, post-synthesis surface chemistry modification of colloidal metal chalcogenide QDs is demonstrated to induce both broadband absorption enhancement and band gap reduction. A comprehensive library of chalcogenol(ate) ligands is exploited to infer the role of surface chemistry on the QD optical absorption: the ligand chalcogenol(ate) binding group mainly determines the narrowing of the optical band gap, which is attributed to the np occupied orbital contribution to the valence band edge, and mediates the absorption enhancement, which is related to the π-conjugation of the ligand pendant moiety, with further contribution from electron donor substituents. These findings point to a description of colloidal QDs that may conceive ligands as part of the overall QD electronic structure, beyond models derived from analogies with core/shell heterostructures, which consider ligands as mere perturbation to the core properties. The enhanced light absorption achieved via surface chemistry modification may be exploited for QD-based applications in which an efficient light-harvesting initiates charge carrier separation or redox processes.
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Affiliation(s)
- Carlo Giansante
- CNR NANOTEC, Istituto di Nanotecnologia, via Monteroni, 73100 Lecce, Italy.
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15
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Bronstein ND, Martinez MS, Kroupa DM, Vörös M, Lu H, Brawand NP, Nozik AJ, Sellinger A, Galli G, Beard MC. Designing Janus Ligand Shells on PbS Quantum Dots using Ligand-Ligand Cooperativity. ACS NANO 2019; 13:3839-3846. [PMID: 30855942 DOI: 10.1021/acsnano.9b00191] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We present a combined experimental and theoretical study of ligand-ligand cooperativity during X-type carboxylate-to-carboxylate ligand exchange reactions on PbS quantum dot surfaces. We find that the ligand dipole moment (varied through changing the substituents on the benzene ring of cinnamic acid derivatives) impacts the ligand-exchange isotherms; in particular, ligands with large electron withdrawing character result in a sharper transition from an oleate-dominated ligand shell to a cinnamate-dominated ligand shell. We developed a two-dimensional lattice model to simulate the ligand-exchange isotherms that accounts for the difference in ligand binding energy as well as ligand-ligand cooperativity. Our model shows that ligands with larger ligand-ligand coupling energy exhibit sharper isotherms indicating an order-disorder phase transition. Finally, we developed an anisotropic Janus ligand shell by taking advantage of the ligand-ligand cooperative ligand exchanges. We monitored the Janus ligand shell using 19F nuclear magnetic resonance, showing that when the ligand-ligand coupling energy falls within the order region of the phase diagram, Janus ligand shells can be constructed.
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Affiliation(s)
- Noah D Bronstein
- Chemistry & Nanoscience Center, National Renewable Energy Laboratory , Golden , Colorado 80401 , United States
| | - Marissa S Martinez
- Chemistry & Nanoscience Center, National Renewable Energy Laboratory , Golden , Colorado 80401 , United States
- Department of Chemistry and Biochemistry , University of Colorado , Boulder , Colorado 80309 , United States
| | - Daniel M Kroupa
- Chemistry & Nanoscience Center, National Renewable Energy Laboratory , Golden , Colorado 80401 , United States
- Department of Chemistry and Biochemistry , University of Colorado , Boulder , Colorado 80309 , United States
| | - Márton Vörös
- Materials Science Division , Argonne National Laboratory , Lemont , Illinois 60439 , United States
- Institute for Molecular Engineering, University of Chicago , Chicago , Illinois 60637 , United States
| | - Haipeng Lu
- Chemistry & Nanoscience Center, National Renewable Energy Laboratory , Golden , Colorado 80401 , United States
| | - Nicholas P Brawand
- Institute for Molecular Engineering, University of Chicago , Chicago , Illinois 60637 , United States
| | - Arthur J Nozik
- Chemistry & Nanoscience Center, National Renewable Energy Laboratory , Golden , Colorado 80401 , United States
- Department of Chemistry and Biochemistry , University of Colorado , Boulder , Colorado 80309 , United States
| | - Alan Sellinger
- Chemistry & Nanoscience Center, National Renewable Energy Laboratory , Golden , Colorado 80401 , United States
- Department of Chemistry and Materials Science Program , Colorado School of Mines , Golden , Colorado 80401 , United States
| | - Giulia Galli
- Materials Science Division , Argonne National Laboratory , Lemont , Illinois 60439 , United States
- Institute for Molecular Engineering, University of Chicago , Chicago , Illinois 60637 , United States
- Department of Chemistry , University of Chicago , Chicago , Illinois 60637 , United States
| | - Matthew C Beard
- Chemistry & Nanoscience Center, National Renewable Energy Laboratory , Golden , Colorado 80401 , United States
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Lu H, Carroll GM, Neale NR, Beard MC. Infrared Quantum Dots: Progress, Challenges, and Opportunities. ACS NANO 2019; 13:939-953. [PMID: 30648854 DOI: 10.1021/acsnano.8b09815] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Infrared technologies provide tremendous value to our modern-day society. The need for easy-to-fabricate, solution-processable, tunable infrared active optoelectronic materials has driven the development of infrared colloidal quantum dots, whose band gaps can readily be tuned by dimensional constraints due to the quantum confinement effect. In this Perspective, we summarize recent progress in the development of infrared quantum dots both as infrared light emitters ( e.g., in light-emitting diodes, biological imaging, etc.) as well as infrared absorbers ( e.g., in photovoltaics, solar fuels, photon up-conversion, etc.), focusing on how fundamental breakthroughs in synthesis, surface chemistry, and characterization techniques are facilitating the implementation of these nanostructures into exploratory device architectures as well as in emerging applications. We discuss the ongoing challenges and opportunities associated with infrared colloidal quantum dots.
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Affiliation(s)
- Haipeng Lu
- Chemistry & Nanoscience Center , National Renewable Energy Laboratory , Golden , Colorado 80401 , United States
| | - Gerard M Carroll
- Chemistry & Nanoscience Center , National Renewable Energy Laboratory , Golden , Colorado 80401 , United States
| | - Nathan R Neale
- Chemistry & Nanoscience Center , National Renewable Energy Laboratory , Golden , Colorado 80401 , United States
| | - Matthew C Beard
- Chemistry & Nanoscience Center , National Renewable Energy Laboratory , Golden , Colorado 80401 , United States
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Abstract
From a niche field over 30 years ago, quantum dots (QDs) have developed into viable materials for many commercial optoelectronic devices. We discuss the advancements in Pb-based QD solar cells (QDSCs) from a viewpoint of the pathways an excited state can take when relaxing back to the ground state. Systematically understanding the fundamental processes occurring in QDs has led to improvements in solar cell efficiency from ~3% to over 13% in 8 years. We compile data from ~200 articles reporting functioning QDSCs to give an overview of the current limitations in the technology. We find that the open circuit voltage limits the device efficiency and propose some strategies for overcoming this limitation.
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