1
|
Jia X, Soprani L, Londi G, Hosseini SM, Talnack F, Mannsfeld S, Shoaee S, Neher D, Reineke S, Muccioli L, D'Avino G, Vandewal K, Beljonne D, Spoltore D. Molecularly induced order promotes charge separation through delocalized charge-transfer states at donor-acceptor heterojunctions. MATERIALS HORIZONS 2024; 11:173-183. [PMID: 37915305 DOI: 10.1039/d3mh00526g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2023]
Abstract
The energetic landscape at the interface between electron donating and accepting molecular materials favors efficient conversion of intermolecular charge-transfer (CT) states into free charge carriers (FCC) in high-performance organic solar cells. Here, we elucidate how interfacial energetics, charge generation and radiative recombination are affected by molecular arrangement. We experimentally determine the CT dissociation properties of a series of model, small molecule donor-acceptor blends, where the used acceptors (B2PYMPM, B3PYMPM and B4PYMPM) differ only in the nitrogen position of their lateral pyridine rings. We find that the formation of an ordered, face-on molecular packing in B4PYMPM is beneficial to efficient, field-independent charge separation, leading to fill factors above 70% in photovoltaic devices. This is rationalized by a comprehensive computational protocol showing that, compared to the more amorphous and isotropically oriented B2PYMPM, the higher structural order of B4PYMPM molecules leads to more delocalized CT states. Furthermore, we find no correlation between the quantum efficiency of FCC radiative recombination and the bound or unbound nature of the CT states. This work highlights the importance of structural ordering at donor-acceptor interfaces for efficient FCC generation and shows that less bound CT states do not preclude efficient radiative recombination.
Collapse
Affiliation(s)
- Xiangkun Jia
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics, Technische Universität Dresden, 01187 Dresden, Germany
| | - Lorenzo Soprani
- Department of Industrial Chemistry "Toso Montanari", University of Bologna, 40136 Bologna, Italy
| | - Giacomo Londi
- Laboratory for Chemistry of Novel Materials, University of Mons, B-7000 Mons, Belgium.
| | - Seyed Mehrdad Hosseini
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
| | - Felix Talnack
- Center for Advancing Electronics Dresden (cfaed) and Faculty of Electrical and Computer Engineering, Technische Universität Dresden, 01062 Dresden, Germany
| | - Stefan Mannsfeld
- Center for Advancing Electronics Dresden (cfaed) and Faculty of Electrical and Computer Engineering, Technische Universität Dresden, 01062 Dresden, Germany
| | - Safa Shoaee
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
| | - Dieter Neher
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
| | - Sebastian Reineke
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics, Technische Universität Dresden, 01187 Dresden, Germany
| | - Luca Muccioli
- Department of Industrial Chemistry "Toso Montanari", University of Bologna, 40136 Bologna, Italy
| | - Gabriele D'Avino
- Grenoble Alpes University, CNRS, Grenoble INP, Institut Néel, 25 rue des Martyrs, 38042 Grenoble, France
| | - Koen Vandewal
- Institute for Materials Research (IMO-IMOMEC), Hasselt University, Wetenschapspark 1, 3590 Diepenbeek, Belgium.
| | - David Beljonne
- Laboratory for Chemistry of Novel Materials, University of Mons, B-7000 Mons, Belgium.
| | - Donato Spoltore
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics, Technische Universität Dresden, 01187 Dresden, Germany
- Institute for Materials Research (IMO-IMOMEC), Hasselt University, Wetenschapspark 1, 3590 Diepenbeek, Belgium.
- Department of Mathematical, Physical and Computer Sciences, University of Parma, V.le delle Scienze 7/A, 43124 Parma, Italy.
| |
Collapse
|
2
|
Meskers SCJ. The Exciton Model for Molecular Materials: Past, Present and Future? Chemphyschem 2023:e202300666. [PMID: 38010974 DOI: 10.1002/cphc.202300666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 10/09/2023] [Indexed: 11/29/2023]
Abstract
In assemblies of identical molecules or chromophores, electronic excitations can be described as excitons, bound electron-hole pairs that can move from site to site as a pair in a coherent manner. The understanding of excitons is crucial when trying to engineer favorable photophysical properties through structuring organic molecular matter. In recent decades, limitations of the concept of an exciton have become clear. The exciton can hybridize with phonon and photons. To clarify these issues, the exciton is discussed within the broader context of the gauge properties of the electromagnetic force.
Collapse
Affiliation(s)
- Stefan C J Meskers
- Molecular Materials and Nanosystems Institute for Complex Molecular Systems, Department of Chemical Engineering and Chemistry, Eindhoven university of Technology, 5600 MB, Eindhoven, The Netherlands
| |
Collapse
|
3
|
Balzer D, Kassal I. Even a little delocalization produces large kinetic enhancements of charge-separation efficiency in organic photovoltaics. SCIENCE ADVANCES 2022; 8:eabl9692. [PMID: 35960797 PMCID: PMC9374333 DOI: 10.1126/sciadv.abl9692] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 06/28/2022] [Indexed: 05/25/2023]
Abstract
In organic photovoltaics, charges can separate efficiently even if their Coulomb attraction is an order of magnitude greater than the available thermal energy. Delocalization has been suggested to explain this fact, because it could increase the initial separation of charges in the charge-transfer (CT) state, reducing their attraction. However, understanding the mechanism requires a kinetic model of delocalized charge separation, which has proven difficult because it involves tracking the correlated quantum-mechanical motion of the electron and the hole in large simulation boxes required for disordered materials. Here, we report the first three-dimensional simulations of charge-separation dynamics in the presence of disorder, delocalization, and polaron formation, finding that even slight delocalization, across less than two molecules, can substantially enhance the charge-separation efficiency, even starting with thermalized CT states. Delocalization does not enhance efficiency by reducing the Coulomb attraction; instead, the enhancement is a kinetic effect produced by the increased overlap of electronic states.
Collapse
|
4
|
Cui Y, Yao HF, Xu Y, Bi PQ, Zhang JQ, Zhang T, Hong L, Chen ZH, Wei ZX, Hao XT, Hou JH. 100 cm2 Organic Photovoltaic Cells with 23% Efficiency under Indoor Illumination. CHINESE JOURNAL OF POLYMER SCIENCE 2022. [DOI: 10.1007/s10118-022-2761-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
5
|
Carr JM, Allen TG, Larson BW, Davydenko IG, Dasari RR, Barlow S, Marder SR, Reid OG, Rumbles G. Short and long-range electron transfer compete to determine free-charge yield in organic semiconductors. MATERIALS HORIZONS 2022; 9:312-324. [PMID: 34787147 DOI: 10.1039/d1mh01331a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Understanding how Frenkel excitons efficiently split to form free-charges in low-dielectric constant organic semiconductors has proven challenging, with many different models proposed in recent years to explain this phenomenon. Here, we present evidence that a simple model invoking a modest amount of charge delocalization, a sum over the available microstates, and the Marcus rate constant for electron transfer can explain many seemingly contradictory phenomena reported in the literature. We use an electron-accepting fullerene host matrix dilutely sensitized with a series of electron donor molecules to test this hypothesis. The donor series enables us to tune the driving force for photoinduced electron transfer over a range of 0.7 eV, mapping out normal, optimal, and inverted regimes for free-charge generation efficiency, as measured by time-resolved microwave conductivity. However, the photoluminescence of the donor is rapidly quenched as the driving force increases, with no evidence for inverted behavior, nor the linear relationship between photoluminescence quenching and charge-generation efficiency one would expect in the absence of additional competing loss pathways. This behavior is self-consistently explained by competitive formation of bound charge-transfer states and long-range or delocalized free-charge states, where both rate constants are described by the Marcus rate equation. Moreover, the model predicts a suppression of the inverted regime for high-concentration blends and efficient ultrafast free-charge generation, providing a mechanistic explanation for why Marcus-inverted-behavior is rarely observed in device studies.
Collapse
Affiliation(s)
- Joshua M Carr
- University of Colorado Boulder, Materials Science & Engineering Program, Boulder, CO, 80303, USA
| | - Taylor G Allen
- National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, CO, 80401, USA.
| | - Bryon W Larson
- National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, CO, 80401, USA.
| | - Iryna G Davydenko
- Georgia Institute of Technology, School of Chemistry and Biochemistry, Atlanta, GA, 30332, USA
| | - Raghunath R Dasari
- Georgia Institute of Technology, School of Chemistry and Biochemistry, Atlanta, GA, 30332, USA
| | - Stephen Barlow
- National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, CO, 80401, USA.
- Georgia Institute of Technology, School of Chemistry and Biochemistry, Atlanta, GA, 30332, USA
- University of Colorado Boulder, Renewable and Sustainable Energy Institute, Boulder, CO, 80303, USA
| | - Seth R Marder
- National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, CO, 80401, USA.
- Georgia Institute of Technology, School of Chemistry and Biochemistry, Atlanta, GA, 30332, USA
- University of Colorado Boulder, Renewable and Sustainable Energy Institute, Boulder, CO, 80303, USA
- University of Colorado Boulder, Department of Chemistry, Boulder, CO, 80303, USA
- University of Colorado Boulder, Department of Chemical and Biological Engineering, Boulder, CO, 80303, USA
| | - Obadiah G Reid
- National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, CO, 80401, USA.
- University of Colorado Boulder, Renewable and Sustainable Energy Institute, Boulder, CO, 80303, USA
| | - Garry Rumbles
- National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, CO, 80401, USA.
- University of Colorado Boulder, Renewable and Sustainable Energy Institute, Boulder, CO, 80303, USA
- University of Colorado Boulder, Department of Chemistry, Boulder, CO, 80303, USA
| |
Collapse
|
6
|
Liang Q, Hu Z, Yao J, Wu Z, Ding Z, Zhao K, Jiao X, Liu J, Huang W. Blending Donors with Different Molecular Weights: An Efficient Strategy to Resolve the Conflict between Coherence Length and Intermixed Phase in Polymer/Nonfullerene Solar Cells. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2103804. [PMID: 34825447 DOI: 10.1002/smll.202103804] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 10/15/2021] [Indexed: 06/13/2023]
Abstract
Long coherence lengths (CLs) of crystals and proper intermixed phase amount guarantee charge transport and exciton dissociate efficiently, which is crucial for organic solar cells (OSCs) to achieve high device performance. However, extending CLs usually reduces the intermixed phase, leading to an insufficient interface for exciton dissociation. Herein, a strategy using a binary polymer with different molecular weights as donor is employed, that is, poly(3-hexylthiophene-2,5-diyl) (P3HT) with high (P3HT-H) and low (P3HT-L) molecular weight are blended as donor, and (5Z,5'Z)-5,5'-(((4,4,9,9-tetraoctyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b']dithiophene-2,7-diyl)bis(benzo[c][1,2,5]thiadiazole-7,4-diyl))bis(methanylylidene))bis(3-ethyl-2-thioxothiazolidin-4-one) (O-IDTBR) is used as acceptor. In kinetics, the entanglements of P3HT-H are relieved due to the higher molecular diffusivity of P3HT-L. In thermodynamics, the miscibility of P3HT-L/O-IDTBR, P3HT-H/O-IDTBR, and P3HT-L/P3HT-H blends increases in turn. Hence, P3HT forms a more ordered structure with longer CLs after adding P3HT-L, which also drives O-IDTBR dispersed in P3HT crystalline regions diffuse to the O-IDTBR crystalline regions to further self-organize. Consequently, the CLs of both P3HT and O-IDTBR are extended, while keeping the intermixed phase amount proper. The optimized microstructure boosts device performance from 7.03% to 7.80%, which is one of the highest values reported for P3HT/O-IDTBR blends. This is a novel way to solve the conflict mentioned above, which may provide guidance to finely regulating the morphology of the active layer.
Collapse
Affiliation(s)
- Qiuju Liang
- Northwestern Polytechnical University, Xi'an, 710129, China
| | - Zhangbo Hu
- Northwestern Polytechnical University, Xi'an, 710129, China
| | - Jianhong Yao
- Northwestern Polytechnical University, Xi'an, 710129, China
| | - Zihao Wu
- Northwestern Polytechnical University, Xi'an, 710129, China
| | | | - Kui Zhao
- Shaanxi Normal University, Xi'an, 710119, China
| | - Xuechen Jiao
- Monash University, Wellington Road, Clayton, VIC, 3800, Australia
| | - Jiangang Liu
- Northwestern Polytechnical University, Xi'an, 710129, China
| | - Wei Huang
- Northwestern Polytechnical University, Xi'an, 710129, China
| |
Collapse
|
7
|
Radford CL, Kelly TL. Controlling solid-state structure and film morphology in non-fullerene organic photovoltaic devices. CAN J CHEM 2021. [DOI: 10.1139/cjc-2021-0134] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Organic solar cells (OSCs) have long promised to provide renewable energy in a scalable, cost-effective way; however, for years, their relatively low efficiency has been a significant barrier to commercialization. Recent progress on cell efficiency means that OSCs are now much more competitive with other established technologies. These key advancements have come from better understanding and controlling the molecular structure, solid-state packing, and film morphology of the light absorbing layer. This focused review will explore the different ways that the solid-state structure and film morphology of the light absorbing layer can be controlled. It will examine the key features of an efficient light absorbing layer and present guiding principles for creating efficient OSCs. The future directions and remaining research questions of this field will be briefly discussed.
Collapse
Affiliation(s)
- Chase L. Radford
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada
| | - Timothy L. Kelly
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada
| |
Collapse
|
8
|
Wang GD, Liu ZX, Qiu BB, Zhang ZG, Wang R, Wang XY, Ma J, Li YF, Xiao M, Zhang CF. Ultrafast electron transfer in all-small-molecule photovoltaic blends promoted by intermolecular interactions in cyanided donors. CHINESE J CHEM PHYS 2021. [DOI: 10.1063/1674-0068/cjcp2109179] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Guo-dong Wang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Zhi-xing Liu
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Bei-bei Qiu
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Zhi-guo Zhang
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- State key Laboratory of Chemical Resource Engineering, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Rui Wang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Xiao-yong Wang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Jing Ma
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
| | - Yong-fang Li
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Min Xiao
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA
| | - Chun-feng Zhang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
| |
Collapse
|
9
|
Kaiser W, Janković V, Vukmirović N, Gagliardi A. Nonequilibrium Thermodynamics of Charge Separation in Organic Solar Cells. J Phys Chem Lett 2021; 12:6389-6397. [PMID: 34232672 DOI: 10.1021/acs.jpclett.1c01817] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
This work presents a novel theoretical description of the nonequilibrium thermodynamics of charge separation in organic solar cells (OSCs). Using stochastic thermodynamics, we take realistic state populations derived from the phonon-assisted dynamics of electron-hole pairs within photoexcited organic bilayers to connect the kinetics with the free energy profile of charge separation. Hereby, we quantify for the first time the difference between nonequilibrium and equilibrium free energy profile. We analyze the impact of energetic disorder and delocalization on free energy, average energy, and entropy. For a high disorder, the free energy profile is well-described as equilibrated. We observe significant deviations from equilibrium for delocalized electron-hole pairs at a small disorder, implying that charge separation in efficient OSCs proceeds via a cold but nonequilibrated pathway. Both a large Gibbs entropy and large initial electron-hole distance provide an efficient charge separation, while a decrease in the free energy barrier does not necessarily enhance charge separation.
Collapse
Affiliation(s)
- Waldemar Kaiser
- Department of Electrical and Computer Engineering, Technical University of Munich, Karlstraße 45, 80333 Munich, Germany
| | - Veljko Janković
- Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia
| | - Nenad Vukmirović
- Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia
| | - Alessio Gagliardi
- Department of Electrical and Computer Engineering, Technical University of Munich, Karlstraße 45, 80333 Munich, Germany
| |
Collapse
|
10
|
Yan J, Rezasoltani E, Azzouzi M, Eisner F, Nelson J. Influence of static disorder of charge transfer state on voltage loss in organic photovoltaics. Nat Commun 2021; 12:3642. [PMID: 34131145 PMCID: PMC8206127 DOI: 10.1038/s41467-021-23975-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 05/26/2021] [Indexed: 02/05/2023] Open
Abstract
Spectroscopic measurements of charge transfer (CT) states provide valuable insight into the voltage losses in organic photovoltaics (OPVs). Correct interpretation of CT-state spectra depends on knowledge of the underlying broadening mechanisms, and the relative importance of molecular vibrational broadening and variations in the CT-state energy (static disorder). Here, we present a physical model, that obeys the principle of detailed balance between photon absorption and emission, of the impact of CT-state static disorder on voltage losses in OPVs. We demonstrate that neglect of CT-state disorder in the analysis of spectra may lead to incorrect estimation of voltage losses in OPV devices. We show, using measurements of polymer:non-fullerene blends of different composition, how our model can be used to infer variations in CT-state energy distribution that result from variations in film microstructure. This work highlights the potential impact of static disorder on the characteristics of disordered organic blend devices.
Collapse
Affiliation(s)
- Jun Yan
- Department of Physics and Centre for Processable Electronics, Imperial College London, London, UK.
| | - Elham Rezasoltani
- Department of Physics and Centre for Processable Electronics, Imperial College London, London, UK
| | - Mohammed Azzouzi
- Department of Physics and Centre for Processable Electronics, Imperial College London, London, UK
| | - Flurin Eisner
- Department of Physics and Centre for Processable Electronics, Imperial College London, London, UK
| | - Jenny Nelson
- Department of Physics and Centre for Processable Electronics, Imperial College London, London, UK.
| |
Collapse
|
11
|
Dhakal P, Ferron T, Alotaibi A, Murcia V, Alqahtani O, Collins BA. Evidence for Field-Dependent Charge Separation Caused by Mixed Phases in Polymer-Fullerene Organic Solar Cells. J Phys Chem Lett 2021; 12:1847-1853. [PMID: 33577332 DOI: 10.1021/acs.jpclett.0c03863] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
As organic photovoltaic performance approaches 20% efficiencies, causal structure-performance relationships must be established for devices to realize theoretical limits and become commercially competitive. Here, we reveal evidence of a causal relationship between mixed donor-acceptor interfaces and charge generation in polymer-fullerene solar cells. To do this, we combine a holistic loss analysis of device performance with quantitative synchrotron X-ray nanocharacterization to identify a >98% anticorrelation between field-dependent geminate recombination and nanodomain purity. Importantly, our analysis eliminates other possible explanations of the performance trends, a requirement to establish causality. The unprecedented granular level of our analysis also separates field-dependent and field-independent recombination at the interface, where we find for the first time that this system is free of field-independent recombination, a loss channel that plagues high-performance systems, including those with non-fullerene acceptors. This result broadens the case that minimizing mixed phases to promote sharp interfaces between pure aggregated domains is the ideal nanostructure for realizing theoretical efficiency limits of organic photovoltaics.
Collapse
Affiliation(s)
- Prabodh Dhakal
- Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164, United States
| | - Thomas Ferron
- Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164, United States
| | - Awwad Alotaibi
- Materials Science and Engineering Program, Washington State University, Pullman, Washington 99164, United States
| | - Victor Murcia
- Materials Science and Engineering Program, Washington State University, Pullman, Washington 99164, United States
| | - Obaid Alqahtani
- Materials Science and Engineering Program, Washington State University, Pullman, Washington 99164, United States
- Department of Physics, Prince Sattam bin Abdulaziz University, Alkharj, 11942, Kingdom of Saudi Arabia
| | - Brian A Collins
- Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164, United States
- Materials Science and Engineering Program, Washington State University, Pullman, Washington 99164, United States
| |
Collapse
|
12
|
Balzer D, Smolders TJAM, Blyth D, Hood SN, Kassal I. Delocalised kinetic Monte Carlo for simulating delocalisation-enhanced charge and exciton transport in disordered materials. Chem Sci 2020; 12:2276-2285. [PMID: 34163994 PMCID: PMC8179315 DOI: 10.1039/d0sc04116e] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Charge transport is well understood in both highly ordered materials (band conduction) or highly disordered ones (hopping conduction). In moderately disordered materials—including many organic semiconductors—the approximations valid in either extreme break down, making it difficult to accurately model the conduction. In particular, describing wavefunction delocalisation requires a quantum treatment, which is difficult in disordered materials that lack periodicity. Here, we present the first three-dimensional model of partially delocalised charge and exciton transport in materials in the intermediate disorder regime. Our approach is based on polaron-transformed Redfield theory, but overcomes several computational roadblocks by mapping the quantum-mechanical techniques onto kinetic Monte Carlo. Our theory, delocalised kinetic Monte Carlo (dKMC), shows that the fundamental physics of transport in moderately disordered materials is that of charges hopping between partially delocalised electronic states. Our results reveal why standard kinetic Monte Carlo can dramatically underestimate mobilities even in disordered organic semiconductors, where even a little delocalisation can substantially enhance mobilities, as well as showing that three-dimensional calculations capture important delocalisation effects neglected in lower-dimensional approximations. The first three-dimensional model of transport in moderately disordered materials shows that a little delocalisation can dramatically enhance mobilities.![]()
Collapse
Affiliation(s)
- Daniel Balzer
- School of Chemistry and University of Sydney Nano Institute, University of Sydney NSW 2006 Australia
| | - Thijs J A M Smolders
- School of Chemistry and University of Sydney Nano Institute, University of Sydney NSW 2006 Australia .,Institute for Molecules and Materials, Radboud University 6525 AJ Nijmegen The Netherlands
| | - David Blyth
- School of Mathematics and Physics, University of Queensland St. Lucia QLD 4072 Australia
| | - Samantha N Hood
- School of Mathematics and Physics, University of Queensland St. Lucia QLD 4072 Australia
| | - Ivan Kassal
- School of Chemistry and University of Sydney Nano Institute, University of Sydney NSW 2006 Australia
| |
Collapse
|
13
|
Liu J, Zeng S, Zhang Z, Peng J, Liang Q. Optimizing the Phase-Separated Domain Size of the Active Layer via Sequential Crystallization in All-Polymer Solar Cells. J Phys Chem Lett 2020; 11:2314-2321. [PMID: 32138516 DOI: 10.1021/acs.jpclett.0c00249] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The proper domain size of the active layer plays a key role in determining the exciton dissociation and charge transport in all-polymer solar cells (all-PSCs). However, fine-tuning the domain size remains challenging due to low glass transition temperature and negligible mixing entropy in polymer blends. Herein, we systematically studied the influence of "crystallization kinetics" on the domain size and proposed that if the donor and acceptor crystallize simultaneously, they are prone to form a large domain, while if sequential crystallization of the donor and acceptor occurs, a fine phase separation structure with the proper domain size can be obtained. Taking PBDB-T/PNDI blends for instance, the domain size was decreased by using sequential crystallization; meanwhile, the crystallinity and molecular orientation were also optimized, boosting the power conversion efficiency from 6.55% to 7.78%. This work provides a novel way to finely tune the heterojunction phase separation structures.
Collapse
Affiliation(s)
- Jiangang Liu
- School of Electronics and Information, Northwestern Polytechnical University, Xi'an 710129, China
- Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong Province, Shantou University, Shantou 515063, China
| | - Shuyi Zeng
- Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong Province, Shantou University, Shantou 515063, China
| | - Zhiguo Zhang
- College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Jing Peng
- Organtec Ltd., Changping Sci&Tech Park, Changping District, Beijing 102200, China
| | - Qiuju Liang
- School of Microelectronics, Northwestern Polytechnical University, Xi'an 710129, China
| |
Collapse
|