1
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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.
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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.
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2
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Mondal S, Chowdhury U, Dey S, Habib M, Mora Perez C, Frauenheim T, Sarkar R, Pal S, Prezhdo OV. Controlling Charge Carrier Dynamics in Porphyrin Nanorings by Optically Active Templates. J Phys Chem Lett 2023; 14:11384-11392. [PMID: 38078872 PMCID: PMC10749466 DOI: 10.1021/acs.jpclett.3c03304] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 12/01/2023] [Accepted: 12/01/2023] [Indexed: 12/22/2023]
Abstract
Understanding the dynamics of photogenerated charge carriers is essential for enhancing the performance of solar and optoelectronic devices. Using atomistic quantum dynamics simulations, we demonstrate that a short π-conjugated optically active template can be used to control hot carrier relaxation, charge carrier separation, and carrier recombination in light-harvesting porphyrin nanorings. Relaxation of hot holes is slowed by 60% with an optically active template compared to that with an analogous optically inactive template. Both systems exhibit subpicosecond electron transfer from the photoactive core to the templates. Notably, charge recombination is suppressed 6-fold by the optically active template. The atomistic time-domain simulations rationalize these effects by the extent of electron and hole localization, modification of the density of states, participation of distinct vibrational motions, and changes in quantum coherence. Extension of the hot carrier lifetime and reduction of charge carrier recombination, without hampering charge separation, demonstrate a strategy for enhancing efficiencies of energy materials with optically active templates.
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Affiliation(s)
- Shrabanti Mondal
- Department
of Chemistry, University of Gour Banga, Malda 732103, India
| | - Uttam Chowdhury
- Department
of Chemistry, University of Gour Banga, Malda 732103, India
| | - Subhajit Dey
- Department
of Chemistry, University of Gour Banga, Malda 732103, India
| | - Md Habib
- Department
of Chemistry, University of Gour Banga, Malda 732103, India
- Department
of Chemistry, Sripat Singh College, Jiaganj 742122, India
| | - Carlos Mora Perez
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Thomas Frauenheim
- Bremen
Center
for Computational Materials Science, Universität
Bremen, Bremen 28359, Germany
- Beijing
Computational Science Research Center, Beijing 100193, China
- Shenzhen
JL Computational Science and Applied Research Institute, Shenzhen 518109, China
| | - Ritabrata Sarkar
- Department
of Chemistry, University of Gour Banga, Malda 732103, India
- Bremen
Center
for Computational Materials Science, Universität
Bremen, Bremen 28359, Germany
| | - Sougata Pal
- Department
of Chemistry, University of Gour Banga, Malda 732103, India
| | - Oleg V. Prezhdo
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089, United States
- Department
of Physics and Astronomy, University of
Southern California, Los Angeles, California 90089, United States
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3
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Fujita T, Hoshi T. Ab Initio Study of Charge Separation Dynamics and Pump-Probe Spectroscopy in the P3HT/PCBM Blend. J Phys Chem B 2023; 127:7615-7623. [PMID: 37639551 DOI: 10.1021/acs.jpcb.3c02458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
We develop a bottom-up computational method for excited-state dynamics and time-resolved spectroscopy signals in molecular aggregates, on the basis of ab initio excited-state calculations. As an application, we consider the charge separation dynamics and pump-probe spectroscopy in the amorphous P3HT/PCBM blend. To simulate quantum dynamics and time-resolved spectroscopy, the model Hamiltonian for single-excitation and double-excitation manifolds was derived on the basis of fragment-based excited-state calculations within the GW approximation and the Bethe-Salpeter equation. After elucidating the energetics of the electron-hole separation and examining linear absorption spectrum, we investigated the quantum dynamics of exciton and charge carriers in comparison with the pump-probe transient absorption spectra. In particular, we introduced the pump-probe excited-state absorption (ESA) anisotropy as a spectroscopic signature of charge carrier dynamics after exciton dissociation. We found that the charge separation dynamics can be probed by the pump-probe ESA anisotropy dynamics after charge-transfer excitations. The present study provides the fundamental information for understanding the experimental spectroscopy signals, by elucidating the relationship between the excited states, the exciton and charge carrier dynamics, and time-resolved spectroscopy.
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Affiliation(s)
- Takatoshi Fujita
- Institute for Quantum Life Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Takeo Hoshi
- Department of Mechanical and Physical Engineering, Faculty of Engineering, Tottori University, Tottori-shi 680-8552, Tottori, Japan
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4
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Jemaï G, Chika K, Jemaa Khabthani J, Mayou D. Influence of the electron-vibration coupling on the interfacial charge transfer in organic solar cells: a simple quantum model. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:425001. [PMID: 35926486 DOI: 10.1088/1361-648x/ac8712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 07/27/2022] [Indexed: 06/15/2023]
Abstract
In this paper, we analyze the influence of the electron-vibration interaction on the charge transfer process at the donor-acceptor interface in an organic solar cell. We present an essentially exact numerical analysis for a minimal model with only one vibration mode which is coupled to the charge transfer state. We show that the charge transfer state can be hot or cold depending on the parameters and in particular on the value of the energy of the lowest unoccupied molecular orbital on the donor side. We analyze also different regimes where electron-hole attraction or hybridization effects at the interface can modify the quantum yield of the transfer. We discuss also briefly the possible effects of the other vibration modes that are coupled to the charge either on the donor side or on the acceptor side.
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Affiliation(s)
- Ghassen Jemaï
- Laboratoire de Physique de la Matière Condensée, Département de Physique, Faculté des Sciences de Tunis, Université Tunis El Manar, Campus Universitaire, 1060 Tunis, Tunisia
| | - Khouloud Chika
- Laboratoire de Physique de la Matière Condensée, Département de Physique, Faculté des Sciences de Tunis, Université Tunis El Manar, Campus Universitaire, 1060 Tunis, Tunisia
| | - Jouda Jemaa Khabthani
- Laboratoire de Physique de la Matière Condensée, Département de Physique, Faculté des Sciences de Tunis, Université Tunis El Manar, Campus Universitaire, 1060 Tunis, Tunisia
| | - Didier Mayou
- CNRS, Inst NEEL, F-38042 Grenoble, France
- Université Grenoble Alpes, Inst NEEL, F-38042 Grenoble, France
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5
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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.
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6
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Peng WT, Brey D, Giannini S, Dell’Angelo D, Burghardt I, Blumberger J. Exciton Dissociation in a Model Organic Interface: Excitonic State-Based Surface Hopping versus Multiconfigurational Time-Dependent Hartree. J Phys Chem Lett 2022; 13:7105-7112. [PMID: 35900333 PMCID: PMC9376959 DOI: 10.1021/acs.jpclett.2c01928] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 07/19/2022] [Indexed: 05/20/2023]
Abstract
Quantum dynamical simulations are essential for a molecular-level understanding of light-induced processes in optoelectronic materials, but they tend to be computationally demanding. We introduce an efficient mixed quantum-classical nonadiabatic molecular dynamics method termed eXcitonic state-based Surface Hopping (X-SH), which propagates the electronic Schrödinger equation in the space of local excitonic and charge-transfer electronic states, coupled to the thermal motion of the nuclear degrees of freedom. The method is applied to exciton decay in a 1D model of a fullerene-oligothiophene junction, and the results are compared to the ones from a fully quantum dynamical treatment at the level of the Multilayer Multiconfigurational Time-Dependent Hartree (ML-MCTDH) approach. Both methods predict that charge-separated states are formed on the 10-100 fs time scale via multiple "hot-exciton dissociation" pathways. The results demonstrate that X-SH is a promising tool advancing the simulation of photoexcited processes from the molecular to the true nanomaterials scale.
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Affiliation(s)
- Wei-Tao Peng
- Department
of Physics and Astronomy and Thomas Young Centre, University College London, London WC1E 6BT, United Kingdom
| | - Dominik Brey
- Institute
of Physical and Theoretical Chemistry, Goethe
University Frankfurt, Max-von-Laue-Strasse 7, 60438 Frankfurt am Main, Germany
| | - Samuele Giannini
- Department
of Physics and Astronomy and Thomas Young Centre, University College London, London WC1E 6BT, United Kingdom
| | - David Dell’Angelo
- Department
of Physics and Astronomy and Thomas Young Centre, University College London, London WC1E 6BT, United Kingdom
| | - Irene Burghardt
- Institute
of Physical and Theoretical Chemistry, Goethe
University Frankfurt, Max-von-Laue-Strasse 7, 60438 Frankfurt am Main, Germany
| | - Jochen Blumberger
- Department
of Physics and Astronomy and Thomas Young Centre, University College London, London WC1E 6BT, United Kingdom
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7
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Azzouzi M, Gallop NP, Eisner F, Yan J, Zheng X, Cha H, He Q, Fei Z, Heeney M, Bakulin AA, Nelson J. Reconciling models of interfacial state kinetics and device performance in organic solar cells: impact of the energy offsets on the power conversion efficiency. ENERGY & ENVIRONMENTAL SCIENCE 2022; 15:1256-1270. [PMID: 35419090 PMCID: PMC8924960 DOI: 10.1039/d1ee02788c] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 01/04/2022] [Indexed: 06/14/2023]
Abstract
Achieving the simultaneous increases in the open circuit voltage (V oc), short circuit current (J sc) and fill factor (FF) necessary to further increase the power conversion efficiency (PCE) of organic photovoltaics (OPV) requires a unified understanding of how molecular and device parameters affect all three characteristics. In this contribution, we introduce a framework that for the first time combines different models that have been used separately to describe the different steps of the charge generation and collection processes in OPV devices: a semi-classical rate model for charge recombination processes in OPV devices, zero-dimensional kinetic models for the photogeneration process and exciton dissociation and one-dimensional semiconductor device models. Using this unified multi-scale model in conjunction with experimental techniques (time-resolved absorption spectroscopy, steady-state and transient optoelectronic measurements) that probe the various steps involved in charge generation we can shed light on how the energy offsets in a series of polymer: non-fullerene devices affect the charge carrier generation, collection, and recombination properties of the devices. We find that changing the energy levels of the donor significantly affects not only the transition rates between local-exciton (LE) and charge-transfer (CT) states, but also significantly changes the transition rates between CT and charge-separated (CS) states, challenging the commonly accepted picture of charge generation and recombination. These results show that in order to obtain an accurate picture of charge generation in OPV devices, a variety of different experimental techniques under different conditions in conjunction with a comprehensive model of processes occurring at different time-scales are required.
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Affiliation(s)
- Mohammed Azzouzi
- Department of Physics and Centre for Plastic Electronics, Imperial College London London SW7 2AZ UK
| | - Nathaniel P Gallop
- Department of Chemistry and Centre for Processable Electronics, Imperial College London London W12 0BZ UK
| | - Flurin Eisner
- Department of Physics and Centre for Plastic Electronics, Imperial College London London SW7 2AZ UK
| | - Jun Yan
- Department of Physics and Centre for Plastic Electronics, Imperial College London London SW7 2AZ UK
| | - Xijia Zheng
- Department of Chemistry and Centre for Processable Electronics, Imperial College London London W12 0BZ UK
| | - Hyojung Cha
- Department of Chemistry and Centre for Processable Electronics, Imperial College London London W12 0BZ UK
- Department of Hydrogen & Renewable Energy, Kyungpook National University Daegu 41566 Republic of Korea
| | - Qiao He
- Department of Chemistry and Centre for Processable Electronics, Imperial College London London W12 0BZ UK
| | - Zhuping Fei
- Department of Chemistry and Centre for Processable Electronics, Imperial College London London W12 0BZ UK
- Institute of Molecular Plus, Tianjin Key Laboratory of Molecular Optoelectronic Science, Tianjin University Tianjin 300072 P. R. China
| | - Martin Heeney
- Department of Chemistry and Centre for Processable Electronics, Imperial College London London W12 0BZ UK
| | - Artem A Bakulin
- Department of Chemistry and Centre for Processable Electronics, Imperial College London London W12 0BZ UK
| | - Jenny Nelson
- Department of Physics and Centre for Plastic Electronics, Imperial College London London SW7 2AZ UK
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8
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Potentiality of polymer nanocomposites for sustainable environmental applications: A review of recent advances. POLYMER 2021. [DOI: 10.1016/j.polymer.2021.124184] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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9
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Wanigasekara S, Kattel B, Rudayni F, Chan WL. Extracting Electrons from Delocalized Excitons by Flattening the Energetic Pathway for Charge Separation. J Phys Chem Lett 2021; 12:9047-9054. [PMID: 34516118 DOI: 10.1021/acs.jpclett.1c02228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
At organic donor-acceptor (D-A) interfaces, electron and hole are bound together to form charge transfer (CT) excitons. The electron and hole wave functions in these CT excitons can spatially delocalize. The electron delocalization opens up possibilities of extracting free charges from bound excitons by manipulating the potential energy landscape on the nanoscale. Using a prototype trilayer structure that has a cascade band structure, we show that the yield of charge separation can be doubled as compared to the bilayer counterpart when the thickness of the intermediate layer is around 3 nm. This thickness coincides with the electron delocalization size of CT excitons typically found in these organic films. Tight-binding calculation for the CT states in the trilayer structure further demonstrates that electron delocalization, together with the energy level cascade, can effectively flatten the energetic pathway for charge separation. Hence, it is possible to add nanometer-thick layers between the donor and the acceptor to significantly enhance the charge separation yield.
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Affiliation(s)
- Shanika Wanigasekara
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
| | - Bhupal Kattel
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
| | - Fatimah Rudayni
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
| | - Wai-Lun Chan
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
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10
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Rijal K, Rudayni F, Kafle TR, Chan WL. Collective Effects of Band Offset and Wave Function Dimensionality on Impeding Electron Transfer from 2D to Organic Crystals. J Phys Chem Lett 2020; 11:7495-7501. [PMID: 32812767 DOI: 10.1021/acs.jpclett.0c01796] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Excited-state electron transfer (ET) across molecules/transition metal dichalcogenide crystal (TMDC) interfaces is a critical process for the functioning of various organic/TMDC hybrid optoelectronic devices. Therefore, it is important to understand the fundamental factors that can facilitate or limit the ET rate. Here it is found that an undesirable combination of the interfacial band offset and the spatial dimensionality of the delocalized electron wave function can significantly slow down the ET process. Specifically, it is found that whereas the ET rate from TMDCs (MoS2 and WSe2) to fullerenes is relative insensitive to the band offset, the ET rate from TMDCs to perylene molecules can be reduced by an order of magnitude when the band offset is large. For the perylene crystal, the sensitivity of the ET rate on the band offset is explained by the 1D nature of the electronic wave function, which limits the availability of states with the appropriate energy to accept the electron.
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Affiliation(s)
- Kushal Rijal
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
| | - Fatimah Rudayni
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
| | - Tika R Kafle
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
| | - Wai-Lun Chan
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
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11
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Pérez‐Jiménez ÁJ, Sancho‐García JC. Theoretical Insights for Materials Properties of Cyclic Organic Nanorings. ADVANCED THEORY AND SIMULATIONS 2020. [DOI: 10.1002/adts.202000110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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12
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Kelly A. Exciton dissociation and charge separation at donor–acceptor interfaces from quantum-classical dynamics simulations. Faraday Discuss 2020; 221:547-563. [DOI: 10.1039/c9fd00069k] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Nonadiabatic dynamics simulations based on the quantum-classical Liouville equation are employed to study the real-time dynamics of exciton dissociation and charge separation at a model donor–acceptor interface.
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Affiliation(s)
- Aaron Kelly
- Department of Chemistry
- Dalhousie University
- Halifax
- Canada
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13
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Athanasopoulos S, Bässler H, Köhler A. Disorder vs Delocalization: Which Is More Advantageous for High-Efficiency Organic Solar Cells? J Phys Chem Lett 2019; 10:7107-7112. [PMID: 31661274 DOI: 10.1021/acs.jpclett.9b02866] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We investigate the combined influence of energetic disorder and delocalization on electron-hole charge-transfer state separation efficiency in donor-acceptor organic photovoltaic systems using an analytical hopping model and Monte Carlo calculations, coupled with an effective mass model. Whereas energetic disorder increases the separation yield at intermediate and low electric fields for low-efficiency blends with strongly localized carriers, we find that it reduces dramatically the fill factors and power conversion efficiencies in high-efficiency solar cells that require high carrier delocalization within the conjugated segment and high mobility-lifetime product. We further demonstrate that the initial electron-hole distance and thermalization processes play only a minor role in the separation dynamics.
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Affiliation(s)
- Stavros Athanasopoulos
- Departamento de Física , Universidad Carlos III de Madrid , Avenida Universidad 30 , 28911 Leganés, Madrid , Spain
| | - Heinz Bässler
- Bayreuth Institute of Macromolecular Research (BIMF) and Bavarian Polymer Institute (BPI) , University of Bayreuth , Bayreuth 95440 , Germany
| | - Anna Köhler
- Bayreuth Institute of Macromolecular Research (BIMF) and Bavarian Polymer Institute (BPI) , University of Bayreuth , Bayreuth 95440 , Germany
- Soft Matter Optoelectronics , University of Bayreuth , Bayreuth 95440 , Germany
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14
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Fujita T, Noguchi Y, Hoshi T. Charge-transfer excited states in the donor/acceptor interface from large-scale GW calculations. J Chem Phys 2019; 151:114109. [PMID: 31542033 DOI: 10.1063/1.5113944] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Predicting the charge-transfer (CT) excited states across the donor/acceptor (D/A) interface is essential for understanding the charge photogeneration process in an organic solar cell. Here, we present a fragment-based GW implementation that can be applied to a D/A interface structure and thus enables accurate determination of the CT states. The implementation is based on the fragmentation approximation of the polarization function and the combined GW and Coulomb-hole plus screened exchange approximations for self-energies. The fragment-based GW is demonstrated by application to the pentacene/C60 interface structure containing more than 2000 atoms. The CT excitation energies were estimated from the quasiparticle energies and electron-hole screened Coulomb interactions; the computed energies are in reasonable agreement with experimental estimates from the external quantum efficiency measurements. We highlight the impact of the induced polarization effects on the electron-hole energetics. The proposed fragment-based GW method offers a first-principles tool to compute the quasiparticle energies and electronic excitation energies of organic materials.
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Affiliation(s)
| | - Yoshifumi Noguchi
- Department of Applied Chemistry and Biochemical Engineering, Graduate School of Engineering, Shizuoka University, Hamamatsu, Shizuoka 432-8561, Japan
| | - Takeo Hoshi
- Department of Applied Mathematics and Physics, Tottori University, Tottori 680-8550, Japan
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15
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Han G, Yi Y. Local Excitation/Charge-Transfer Hybridization Simultaneously Promotes Charge Generation and Reduces Nonradiative Voltage Loss in Nonfullerene Organic Solar Cells. J Phys Chem Lett 2019; 10:2911-2918. [PMID: 31088080 DOI: 10.1021/acs.jpclett.9b00928] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
High power conversion efficiencies in state-of-the-art nonfullerene organic solar cells (NF OSCs) call for elucidation of the underlying working mechanisms of both high photocurrent densities and low nonradiative voltage losses under small energy offsets. Here, to address this fundamental issue, we have assessed the nature of interfacial charge-transfer (CT) states in a representative small-molecule NF OSC (DRTB-T:IT-4F) by time-dependent density functional theory calculations. The calculated results point to the fact that the CT states can borrow considerable oscillator strengths from the energy-close local excitation (LE) states or be fully hybridized with these LE states by molecular aggregation at the donor-acceptor interfaces. The LE/CT hybridization can promote charge generation by direct population of thermalized CT or LE/CT states under illumination. At the same time, the increased oscillator strengths of the lowest CT state will improve the luminescence quantum efficiencies and thus reduce nonradiative voltage losses. Our work suggests that it is crucial to tune the LE/CT hybridization by optimization of the donor and acceptor molecular and interfacial structures to further improve the NF OSC performance.
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Affiliation(s)
- Guangchao Han
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, CAS Research/Education Center for Excellence in Molecular Sciences , Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190 , China
| | - Yuanping Yi
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, CAS Research/Education Center for Excellence in Molecular Sciences , Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190 , China
- University of Chinese Academy Sciences , Beijing 100049 , China
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16
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Zhao ZW, Duan YC, Pan QQ, Gao Y, Wu Y, Geng Y, Zhao L, Zhang M, Su ZM. A probe into underlying factors affecting utrafast charge transfer at Donor/IDIC interface of all-small-molecule nonfullerene organic solar cells. J Photochem Photobiol A Chem 2019. [DOI: 10.1016/j.jphotochem.2019.02.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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17
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Eisner FD, Azzouzi M, Fei Z, Hou X, Anthopoulos TD, Dennis TJS, Heeney M, Nelson J. Hybridization of Local Exciton and Charge-Transfer States Reduces Nonradiative Voltage Losses in Organic Solar Cells. J Am Chem Soc 2019; 141:6362-6374. [DOI: 10.1021/jacs.9b01465] [Citation(s) in RCA: 208] [Impact Index Per Article: 41.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Flurin D. Eisner
- Department of Physics and The Centre for Plastic Electronics Imperial College London, London SW7 2AZ, U.K
| | - Mohammed Azzouzi
- Department of Physics and The Centre for Plastic Electronics Imperial College London, London SW7 2AZ, U.K
| | - Zhuping Fei
- Department of Chemistry and the Centre for Plastic Electronics Imperial College London, London SW7 2AZ, U.K
- Institute of Molecular Plus, Tianjin Key Laboratory of Molecular Optoelectronic Science, Tianjin University, Tianjin 300072, P.R. China
| | - Xueyan Hou
- School of Physics and Astronomy, Queen Mary University of London, London E1 4NS, U.K
| | - Thomas D. Anthopoulos
- Department of Physics and The Centre for Plastic Electronics Imperial College London, London SW7 2AZ, U.K
- King Abdullah University of Science and Technology (KAUST), KAUST Solar Center, Division of Physical Sciences and Engineering Thuwal 23955-6900, Saudi Arabia
| | - T. John S. Dennis
- School of Physics and Astronomy, Queen Mary University of London, London E1 4NS, U.K
| | - Martin Heeney
- Department of Chemistry and the Centre for Plastic Electronics Imperial College London, London SW7 2AZ, U.K
| | - Jenny Nelson
- Department of Physics and The Centre for Plastic Electronics Imperial College London, London SW7 2AZ, U.K
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18
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Collado-Fregoso E, Pugliese SN, Wojcik M, Benduhn J, Bar-Or E, Perdigón Toro L, Hörmann U, Spoltore D, Vandewal K, Hodgkiss JM, Neher D. Energy-Gap Law for Photocurrent Generation in Fullerene-Based Organic Solar Cells: The Case of Low-Donor-Content Blends. J Am Chem Soc 2019; 141:2329-2341. [PMID: 30620190 DOI: 10.1021/jacs.8b09820] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The involvement of charge-transfer (CT) states in the photogeneration and recombination of charge carriers has been an important focus of study within the organic photovoltaic community. In this work, we investigate the molecular factors determining the mechanism of photocurrent generation in low-donor-content organic solar cells, where the active layer is composed of vacuum-deposited C60 and small amounts of organic donor molecules. We find a pronounced decline of all photovoltaic parameters with decreasing CT state energy. Using a combination of steady-state photocurrent measurements and time-delayed collection field experiments, we demonstrate that the power conversion efficiency, and more specifically, the fill factor of these devices, is mainly determined by the bias dependence of photocurrent generation. By combining these findings with the results from ultrafast transient absorption spectroscopy, we show that blends with small CT energies perform poorly because of an increased nonradiative CT state decay rate and that this decay obeys an energy-gap law. Our work challenges the common view that a large energy offset at the heterojunction and/or the presence of fullerene clusters guarantee efficient CT dissociation and rather indicates that charge generation benefits from high CT state energies through a slower decay to the ground state.
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Affiliation(s)
- Elisa Collado-Fregoso
- Department of Physics and Astronomy , University of Potsdam , Karl-Liebknecht-Straße 24-25 , 14476 Potsdam-Golm , Germany
| | - Silvina N Pugliese
- School of Chemical and Physical Sciences , Victoria University of Wellington , Wellington 6040 , New Zealand.,The MacDiarmid Institute for Advanced Materials and Nanotechnology , Wellington 6040 , New Zealand
| | - Mariusz Wojcik
- Institute of Applied Radiation Chemistry , Lodz University of Technology , Wroblewskiego 15 , 93590 Lodz , Poland
| | - Johannes Benduhn
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics , Technische Universität Dresden , Nöthnitzer Straße 61 , 01187 Dresden , Germany
| | - Eyal Bar-Or
- Department of Physics and Astronomy , University of Potsdam , Karl-Liebknecht-Straße 24-25 , 14476 Potsdam-Golm , Germany
| | - Lorena Perdigón Toro
- Department of Physics and Astronomy , University of Potsdam , Karl-Liebknecht-Straße 24-25 , 14476 Potsdam-Golm , Germany
| | - Ulrich Hörmann
- Department of Physics and Astronomy , University of Potsdam , Karl-Liebknecht-Straße 24-25 , 14476 Potsdam-Golm , Germany
| | - Donato Spoltore
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics , Technische Universität Dresden , Nöthnitzer Straße 61 , 01187 Dresden , Germany
| | - Koen Vandewal
- Institute for Materials Research (IMO-IMOMEC) , Hasselt University , Wetenschapspark 1 , 3590 Diepenbeek , Belgium
| | - Justin M Hodgkiss
- School of Chemical and Physical Sciences , Victoria University of Wellington , Wellington 6040 , New Zealand.,The MacDiarmid Institute for Advanced Materials and Nanotechnology , Wellington 6040 , New Zealand
| | - Dieter Neher
- Department of Physics and Astronomy , University of Potsdam , Karl-Liebknecht-Straße 24-25 , 14476 Potsdam-Golm , Germany
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19
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Yang W, Yao Y, Guo P, Sun H, Luo Y. Optimum driving energy for achieving balanced open-circuit voltage and short-circuit current density in organic bulk heterojunction solar cells. Phys Chem Chem Phys 2018; 20:29866-29875. [PMID: 30468215 DOI: 10.1039/c8cp05145c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Organic bulk heterojunction solar cells generally suffer from a trade-off between the open circuit voltage (Voc) and the short circuit current density (Jsc) under a given donor/acceptor (D/A) interfacial energetic offset (or the so-called driving force). Here we theoretically investigate the optimum driving energy required for achieving the balanced Jsc and Voc simultaneously. To this end, the Jscversus the driving force ΔE curves are calculated under two different charge separation mechanisms by employing the drift-diffusion method. For the Marcus incoherent mechanism, the curve features a high plateau in a broad range of ΔE starting from 0.2 eV, which is due to the accumulation of undissociated excitons within their lifetime and signifies the possibility of obtaining a sizable Jsc under a ΔE value much smaller than the reorganization energy. After incorporating both the electron and hole transfer pathways into the device model, the calculated J-V curves are comparable to experimentally measured ones foractual blended systems of different driving forces. For the coherent mechanism, it is demonstrated that the maximum Jsc can also be achieved under the ΔE of 0.2 eV if a large proportion of the high-lying delocalized states are harvested through tuning the density of states for the charge transfer excitons to reduce the sub-gap states. This theoretical work revealed quantitatively the relationship between the interfacial energy offsets and device performance, and also provides some guidelines for identifying the macroscopic features of the actual charge separation mechanisms in bulk heterojunction solar cells.
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Affiliation(s)
- Wenchao Yang
- Key Laboratory of Microelectronics and Energy of Henan, School of Physics and Electronic Engineering, Xinyang Normal University, Xinyang, 464000, China.
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20
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Kafle TR, Kattel B, Wang T, Chan WL. The relationship between the coherent size, binding energy and dissociation dynamics of charge transfer excitons at organic interfaces. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:454001. [PMID: 30265252 DOI: 10.1088/1361-648x/aae50b] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
At organic semiconductor interfaces, an electron and a hole can be bound Coulombically to form an interfacial charge transfer (CT) exciton. It is still under debate how a CT exciton can overcome its strong binding and dissociate into free carriers. Experimentally, capturing the evolution of the CT exciton on time (fs-ps) and length scales (nm) in which the dissociation process occurs is challenging. To overcome this challenge, time-resolved two photon photoemission spectroscopy is used to measure the binding energies and electronic coherent sizes of a series of CT states at organic interfaces, and capture the temporal dynamics of these CT excitons after their excitation. Using zinc phthalocyanine (ZnPc)/fullerene (C60) interface as a model system, it is shown that the interfacial CT process first populates a hot CT state with a coherent size of ~4 nm. Hot and delocalized CT excitons subsequently relax into CT excitons with lower energies and smaller coherent sizes. To correlate the CT exciton properties with the dissociation efficiency, we develop a method that exploits graphene field effect transistors to probe the rate and yield of free carrier generation at the interface. Our results show that exciton dissociation can be more efficient if one can extract electrons from the hot and delocalized CT state. We propose a cascade structure that would serve this purpose.
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Affiliation(s)
- Tika R Kafle
- Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045, United States of America
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21
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Fujita T, Alam MK, Hoshi T. Thousand-atom ab initio calculations of excited states at organic/organic interfaces: toward first-principles investigations of charge photogeneration. Phys Chem Chem Phys 2018; 20:26443-26452. [PMID: 30306163 DOI: 10.1039/c8cp05574b] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Predicting electronically excited states across electron-donor/electron acceptor interfaces is essential for understanding the charge photogeneration process in organic solar cells. However, organic solar cells are large and disordered systems, and their excited states cannot be easily accessed by conventional quantum chemistry approaches. Moreover, a large number of excited states must be obtained to fully understand the charge separation mechanism. Recently, we have developed a novel fragment-based excited state method which can efficiently calculate a large number of states in molecular aggregates. In this article, we demonstrate the large-scale excited-state calculations by investigating interfacial charge transfer (ICT) states across the electron-donor/electron acceptor interfaces. As the model systems, we considered the face-on and edge-on configurations of pentacene/C60 bilayer heterojunction structures. These model structures contain approximately 1.8 × 105 atoms, and their local interface regions containing 2000 atoms were treated quantum mechanically, embedded in the electrostatic potentials from the remaining parts. Therefore, the charge delocalization effect, structural disorder, and the resulting heterogeneous electrostatic and polarizable environments were taken into account in the excited-state calculations. The computed energies of the low-lying ICT states are in reasonable agreement with experimental estimates. By comparing the edge-on and face-on configurations of the pentacene/C60 interfaces, we discuss the influence of interfacial morphologies on the energetics and charge delocalization of ICT states. In addition, we present the detailed characterization of excited states and highlight the importance of hybridization effects between pentacene excited states and ICT states. The large-scale ab initio calculations for the interface systems enabled the exploration of the ICT states, leading to first-principles investigation of the charge separation mechanism in organic solar cells.
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Affiliation(s)
- Takatoshi Fujita
- Institute for Molecular Science, Okazaki, Aichi 444-0865, Japan.
| | - Md Khorshed Alam
- Department of Physics, University of Barisal, Barisal-8200, Bangladesh
| | - Takeo Hoshi
- Department of Applied Mathmatics and Physics, Tottori University, Tottori 680-8550, Japan
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22
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Kato A, Ishizaki A. Non-Markovian Quantum-Classical Ratchet for Ultrafast Long-Range Electron-Hole Separation in Condensed Phases. PHYSICAL REVIEW LETTERS 2018; 121:026001. [PMID: 30085757 DOI: 10.1103/physrevlett.121.026001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Indexed: 06/08/2023]
Abstract
In organic photovoltaic systems, a photogenerated molecular exciton in the donor domain dissociates into a hole and an electron at the donor-acceptor heterojunction, and subsequently separates into free charge carriers that can be extracted as photocurrents. The recombination of the once-separated electron and hole is a major loss mechanism in photovoltaic systems, which controls their performance. Hence, efficient photovoltaic systems need built-in ratchet mechanisms, namely, ultrafast charge separation and retarded charge recombination. In order to obtain insight into the internal working of the experimentally observed ultrafast long-range charge separation and protection against charge recombination, we theoretically investigate a potential ratchet mechanism arising from the combination of quantum delocalization and its destruction by performing numerically accurate quantum-dynamics calculations on a model system. We demonstrate that the non-Markovian effect originating from the slow polaron formation strongly suppresses the electron-transfer reaction back to the interfacial charge-transfer state stabilized at the donor-accepter interface and that it plays a critical role in maintaining the long-range electron-hole separation.
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Affiliation(s)
- Akihito Kato
- Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki 444-8585, Japan
| | - Akihito Ishizaki
- Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki 444-8585, Japan
- School of Physical Sciences, The Graduate University for Advanced Studies, Okazaki 444-8585, Japan
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23
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Fujita T, Mochizuki Y. Development of the Fragment Molecular Orbital Method for Calculating Nonlocal Excitations in Large Molecular Systems. J Phys Chem A 2018; 122:3886-3898. [DOI: 10.1021/acs.jpca.8b00446] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
| | - Yuji Mochizuki
- Department of Chemistry and Research Center for Smart Molecules, Faculty of Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501, Japan
- Institute for Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
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24
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Gluchowski A, Gray KLG, Hood SN, Kassal I. Increases in the Charge Separation Barrier in Organic Solar Cells Due to Delocalization. J Phys Chem Lett 2018; 9:1359-1364. [PMID: 29494769 DOI: 10.1021/acs.jpclett.8b00292] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Because of the low dielectric constant, charges in organic solar cells must overcome a strong Coulomb attraction in order to separate. It has been widely argued that intermolecular delocalization would assist charge separation by increasing the effective initial electron-hole separation in a charge-transfer state, thus decreasing their barrier to separation. Here we show that this is not the case: including more than a small amount of delocalization in models of organic solar cells leads to an increase in the free-energy barrier to charge separation. Therefore, if delocalization were to improve the charge separation efficiency, it would have to do so through nonequilibrium kinetic effects that are not captured by a thermodynamic treatment of the barrier height.
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Affiliation(s)
- Adam Gluchowski
- School of Mathematics and Physics and Centre for Engineered Quantum Systems , The University of Queensland , St. Lucia , QLD 4072 , Australia
| | - Katherine L G Gray
- School of Mathematics and Physics and Centre for Engineered Quantum Systems , The University of Queensland , St. Lucia , QLD 4072 , Australia
| | - Samantha N Hood
- School of Mathematics and Physics and Centre for Engineered Quantum Systems , The University of Queensland , St. Lucia , QLD 4072 , Australia
| | - Ivan Kassal
- School of Chemistry and the University of Sydney Nano Institute , The University of Sydney , Sydney , NSW 2006 , Australia
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25
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Boström EV, Mikkelsen A, Verdozzi C, Perfetto E, Stefanucci G. Charge Separation in Donor-C 60 Complexes with Real-Time Green Functions: The Importance of Nonlocal Correlations. NANO LETTERS 2018; 18:785-792. [PMID: 29266952 DOI: 10.1021/acs.nanolett.7b03995] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We use the nonequilibrium Green function (NEGF) method to perform real-time simulations of the ultrafast electron dynamics of photoexcited donor-C60 complexes modeled by a Pariser-Parr-Pople Hamiltonian. The NEGF results are compared to mean-field Hartree-Fock (HF) calculations to disentangle the role of correlations. Initial benchmarking against numerically highly accurate time-dependent density matrix renormalization group calculations verifies the accuracy of NEGF. We then find that charge-transfer (CT) excitons partially decay into charge separated (CS) states if dynamical nonlocal correlation corrections are included. This CS process occurs in ∼10 fs after photoexcitation. In contrast, the probability of exciton recombination is almost 100% in HF simulations. These results are largely unaffected by nuclear vibrations; the latter become however essential whenever level misalignment hinders the CT process. The robust nature of our findings indicates that ultrafast CS driven by correlation-induced decoherence may occur in many organic nanoscale systems, but it will only be correctly predicted by theoretical treatments that include time-nonlocal correlations.
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Affiliation(s)
- Emil Viñas Boström
- Lund University , Department of Physics and European Theoretical Spectroscopy Facility (ETSF), P.O. Box 118, 221 00 Lund, Sweden
| | - Anders Mikkelsen
- Lund University , Department of Physics and NanoLund, P.O. Box 118, 221 00 Lund, Sweden
| | - Claudio Verdozzi
- Lund University , Department of Physics and European Theoretical Spectroscopy Facility (ETSF), P.O. Box 118, 221 00 Lund, Sweden
| | - Enrico Perfetto
- CNR-ISM , Division of Ultrafast Processes in Materials (FLASHit), Area della Ricerca di Roma 1, Via Salaria Km 29.3, I-00016 Monterotondo Scalo, Italy
- Dipartimento di Fisica and European Theoretical Spectroscopy Facility (ETSF), Università di Roma Tor Vergata , Via della Ricerca Scientifica 1, 00133 Rome, Italy
| | - Gianluca Stefanucci
- Dipartimento di Fisica and European Theoretical Spectroscopy Facility (ETSF), Università di Roma Tor Vergata , Via della Ricerca Scientifica 1, 00133 Rome, Italy
- INFN, Sezione di Roma Tor Vergata , Via della Ricerca Scientifica 1, 00133 Rome, Italy
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26
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Shi L, Lee CK, Willard AP. The Enhancement of Interfacial Exciton Dissociation by Energetic Disorder Is a Nonequilibrium Effect. ACS CENTRAL SCIENCE 2017; 3:1262-1270. [PMID: 29296666 PMCID: PMC5746863 DOI: 10.1021/acscentsci.7b00404] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Indexed: 05/29/2023]
Abstract
The dissociation of excited electron-hole pairs is a microscopic process that is fundamental to the performance of photovoltaic systems. For this process to be successful, the oppositely charged electron and hole must overcome an electrostatic binding energy before they undergo ground state recombination. It has been observed previously that the presence of energetic disorder can lead to a reduction in recombination losses. Here we investigate this effect using a simple model of charge dynamics at a donor-acceptor interface. We consider the effect of spatial variations in electronic energy levels, such as those that arise in disordered molecular systems, on dissociation yield and demonstrate that it is maximized with a finite amount of disorder. We demonstrate that this is a nonequilibrium effect that is mediated by the dissipation driven formation of partially dissociated intermediate states that are long-lived because they cannot easily recombine. We present a kinetic model that incorporates these states and show that it is capable of reproducing similar behavior when it is parametrized with nonequilibrium rates.
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Affiliation(s)
- Liang Shi
- Chemistry and Chemical Biology, University of California, Merced, California 95343, United States
| | - Chee Kong Lee
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Adam P Willard
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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27
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Geng Y, Lee MH, Troisi A. Effect of Infrared Pulse Excitation on the Bound Charge-Transfer State of Photovoltaic Interfaces. J Phys Chem Lett 2017; 8:4872-4877. [PMID: 28927273 DOI: 10.1021/acs.jpclett.7b02088] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The nature and dynamics of the bound charge-transfer (CT) state in the exciton dissociation process in organic solar cells are of critical importance for the understanding of these devices. It was recently demonstrated that this state can be probed by a new experiment in which an infrared (IR) push-pulse is used to dissociate charges from the bound excited state. Here we proposed a simple quantum dynamics model to simulate the excitation of the IR pulse on the bound CT state with model parameters extracted from quantum chemical calculations. We show that the pulse dissociates the CT state following two different mechanisms: one, fairly expected, is the direct excitation of higher energy CT states leading to charge separation; the other, proposed here for the first time, is a rebound mechanism in which the negative charge is transferred in the opposite direction to form the neutral Frenkel exciton state from where it dissociates.
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Affiliation(s)
- Yun Geng
- Department of Chemistry, University of Warwick , Coventry CV4 7AL, U.K
- Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University , Changchun 130024, P.R. China
| | - Myeong H Lee
- Department of Chemistry, University of Warwick , Coventry CV4 7AL, U.K
- Department of Chemistry, University of Liverpool , Liverpool L69 7ZD, U.K
| | - Alessandro Troisi
- Department of Chemistry, University of Liverpool , Liverpool L69 7ZD, U.K
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28
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Zhao ZW, Pan QQ, Li SB, Duan YA, Geng Y, Zhang M, Su ZM. A theoretical exploration of the effect of fluorine and cyano substitutions in diketopyrrolopyrrole-based polymer donor for organic solar cells. J Mol Graph Model 2017; 77:9-16. [PMID: 28802153 DOI: 10.1016/j.jmgm.2017.07.027] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 07/24/2017] [Accepted: 07/25/2017] [Indexed: 11/17/2022]
Abstract
A series of polymer donor materials 1-5 based on diketopyrrolopyrrole and thiophene unit which have been widely used in organic solar cells (OSCs) were investigated based on quantum chemical calculations. The effect of fluorine and cyano substitutions in polymer donor materials was focused on. Based on the investigation on electronic structures and optical properties of the reported molecules 1 and 2 and the analysis on some parameters relevant to charge dissociation ability at donor/acceptor interface constituted by 1 and 2 with PC61BM such as intermolecular charge transfer and recombination, driving force and Coulombic bound energy, we explained why fluorine substitution can improve OPV efficiency through strengthening eletron-withdrawing ability from a theoretical perspective. Then we designed cyano-substituted polymers 3-5 with the aim of obtaining better photovoltaic donor materials. The results reveal that our attempt to design donor materials which can balance large open-circuit voltage (Voc) and high short-circuit current (Jsc) in OSCs has worked out. It is worth noting that the substitutions of fluorine and cyano groups synergistically reduce energy gap and HOMO energy level of polymers 3 and 4. Moreover, 3/PC61BM and 4/PC61BM heterojunctions show over 107 and 104 times higher than 1/PC61BM on the ratios of intermolecular charge transfer and recombination rates (kinter-CT/kinter-CR). Thus, our work here may provide an efficient strategy to design promising donor materials in OPVs and we hope it could be useful in the future experimental synthesis.
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Affiliation(s)
- Zhi-Wen Zhao
- Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Chang Chun, 130024, Jilin, PR China
| | - Qing-Qing Pan
- Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Chang Chun, 130024, Jilin, PR China
| | - Shuang-Bao Li
- Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Chang Chun, 130024, Jilin, PR China
| | - Yu-Ai Duan
- Department of Chemistry, Capital Normal University, Beijing, 100048, PR China
| | - Yun Geng
- Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Chang Chun, 130024, Jilin, PR China.
| | - Min Zhang
- Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Chang Chun, 130024, Jilin, PR China
| | - Zhong-Min Su
- Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Chang Chun, 130024, Jilin, PR China.
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29
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Zheng Z, Egger DA, Brédas JL, Kronik L, Coropceanu V. Effect of Solid-State Polarization on Charge-Transfer Excitations and Transport Levels at Organic Interfaces from a Screened Range-Separated Hybrid Functional. J Phys Chem Lett 2017; 8:3277-3283. [PMID: 28666085 DOI: 10.1021/acs.jpclett.7b01276] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We develop a robust approach for the description of the energetics of charge-transfer (CT) excitations and transport levels at organic interfaces based on a screened range-separated hybrid (SRSH) functional. We find that SRSH functionals correctly capture the effect of solid-state electronic polarization on transport gap renormalization and on screening of the electrostatic electron-hole interaction. With respect to calculations based on nonscreened optimally tuned RSH (long-range corrected) functionals, the SRSH-based calculations can be performed for both isolated molecular complexes and systems embedded in a dielectric medium with the same range-separation parameter, which allows a clear physical interpretation of the results in terms of solid-state polarization without any perturbation of the molecular electronic structure. By considering weakly interacting donor/acceptor complexes of pentacene with C60 and poly-3-hexylthiophene (P3HT) with PCBM, we show that this new approach provides CT-state energies that compare very well with experimental data.
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Affiliation(s)
- Zilong Zheng
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States
| | - David A Egger
- Department of Materials and Interfaces, Weizmann Institute of Science , Rehovoth 76100, Israel
| | - Jean-Luc Brédas
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States
| | - Leeor Kronik
- Department of Materials and Interfaces, Weizmann Institute of Science , Rehovoth 76100, Israel
| | - Veaceslav Coropceanu
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States
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30
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Zheng Z, Tummala NR, Fu YT, Coropceanu V, Brédas JL. Charge-Transfer States in Organic Solar Cells: Understanding the Impact of Polarization, Delocalization, and Disorder. ACS APPLIED MATERIALS & INTERFACES 2017; 9:18095-18102. [PMID: 28481497 DOI: 10.1021/acsami.7b02193] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
We investigate the impact of electronic polarization, charge delocalization, and energetic disorder on the charge-transfer (CT) states formed at a planar C60/pentacene interface. The ability to examine large complexes containing up to seven pentacene molecules and three C60 molecules allows us to take explicitly into account the electronic polarization effects. These complexes are extracted from a bilayer architecture modeled by molecular dynamics simulations and evaluated by means of electronic-structure calculations based on long-range-separated functionals (ωB97XD and BNL) with optimized range-separation parameters. The energies of the lowest charge-transfer states derived for the large complexes are in very good agreement with the experimentally reported values. The average singlet-triplet energy splittings of the lowest CT states are calculated not to exceed 10 meV. The rates of geminate recombination as well as of dissociation of the triplet excitons are also evaluated. In line with experiment, our results indicate that the pentacene triplet excitons generated through singlet fission can dissociate into separated charges on a picosecond time scale, despite the fact that their energy in C60/pentacene heterojunctions is slightly lower than the energies of the lowest CT triplet states.
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Affiliation(s)
- Zilong Zheng
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States
| | - Naga Rajesh Tummala
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States
| | - Yao-Tsung Fu
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States
| | - Veaceslav Coropceanu
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States
| | - Jean-Luc Brédas
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States
- KAUST Solar Center, Division of Physical Science and Engineering, King Abdullah University of Science and Technology , Thuwal 23955-6900, Saudi Arabia
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31
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Volpi R, Linares M. Study of the cold charge transfer state separation at the TQ1/PC 71 BM interface. J Comput Chem 2017; 38:1039-1048. [PMID: 28318028 DOI: 10.1002/jcc.24776] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 02/03/2017] [Accepted: 02/04/2017] [Indexed: 11/09/2022]
Abstract
Charge transfer (CT) state separation is one of the most critical processes in the functioning of an organic solar cell. In this article, we study a bilayer of TQ1 and PC71 BM molecules presenting disorder at the interface, obtained by means of Molecular Dynamics. The study of the CT state splitting can be first analyzed through the CT state splitting diagram, introduced in a previous work. Through this analysis, we identify the possibility of CT state splitting within Marcus Theory in function of the electric field. Once the right range of electric fields has been identified, we perform Kinetic Monte Carlo simulations to estimate percentages and times for the CT state splitting and the free charge carriers collection. Statistical information extracted from these simulations allows us to highlight the importance of polarization and to test the limits of the predictions given by the CT state splitting diagram. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Riccardo Volpi
- Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping, SE-581 83, Sweden
| | - Mathieu Linares
- Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping, SE-581 83, Sweden.,Swedish e-Science Research Centre (SeRC), Linköping University, Linköping, SE-581 83, Sweden
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32
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Athanasopoulos S, Tscheuschner S, Bässler H, Köhler A. Efficient Charge Separation of Cold Charge-Transfer States in Organic Solar Cells Through Incoherent Hopping. J Phys Chem Lett 2017; 8:2093-2098. [PMID: 28436660 DOI: 10.1021/acs.jpclett.7b00595] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We demonstrate that efficient and nearly field-independent charge separation of electron-hole pairs in organic planar heterojunction solar cells can be described by an incoherent hopping mechanism. Using kinetic Monte Carlo simulations that include the effect of on-chain delocalization as well as entropic contributions, we simulate the dissociation of the charge-transfer state in polymer-fullerene bilayer solar cells. The model further explains experimental results of almost field independent charge separation in bilayers of molecular systems with fullerenes and provides important guidelines at the molecular level for maximizing the efficiencies of organic solar cells. Thus, utilizing coherent phenomena is not necessarily required for highly efficient charge separation in organic solar cells.
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Affiliation(s)
- Stavros Athanasopoulos
- Departamento de Física, Universidad Carlos III de Madrid , Avenida Universidad 30, Leganés 28911, Madrid, Spain
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33
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Wang T, Kafle TR, Kattel B, Chan WL. A Multidimensional View of Charge Transfer Excitons at Organic Donor–Acceptor Interfaces. J Am Chem Soc 2017; 139:4098-4106. [DOI: 10.1021/jacs.6b13312] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ti Wang
- Department of Physics and
Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
| | - Tika R. Kafle
- Department of Physics and
Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
| | - Bhupal Kattel
- Department of Physics and
Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
| | - Wai-Lun Chan
- Department of Physics and
Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
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34
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Hartnett PE, Mauck CM, Harris MA, Young RM, Wu YL, Marks TJ, Wasielewski MR. Influence of Anion Delocalization on Electron Transfer in a Covalent Porphyrin Donor–Perylenediimide Dimer Acceptor System. J Am Chem Soc 2017; 139:749-756. [DOI: 10.1021/jacs.6b10140] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Patrick E. Hartnett
- Department of Chemistry and
Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Catherine M. Mauck
- Department of Chemistry and
Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Michelle A. Harris
- Department of Chemistry and
Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Ryan M. Young
- Department of Chemistry and
Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Yi-Lin Wu
- Department of Chemistry and
Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Tobin J. Marks
- Department of Chemistry and
Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Michael R. Wasielewski
- Department of Chemistry and
Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
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35
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Abstract
![]()
The field of organic
photovoltaics has developed rapidly over the
last 2 decades, and small solar cells with power conversion efficiencies
of 13% have been demonstrated. Light absorbed in the organic layers
forms tightly bound excitons that are split into free electrons and
holes using heterojunctions of electron donor and acceptor materials,
which are then extracted at electrodes to give useful electrical power.
This review gives a concise description of the fundamental processes
in photovoltaic devices, with the main emphasis on the characterization
of energy transfer and its role in dictating device architecture,
including multilayer planar heterojunctions, and on the factors that
impact free carrier generation from dissociated excitons. We briefly
discuss harvesting of triplet excitons, which now attracts substantial
interest when used in conjunction with singlet fission. Finally, we
introduce the techniques used by researchers for characterization
and engineering of bulk heterojunctions to realize large photocurrents,
and examine the formed morphology in three prototypical blends.
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Affiliation(s)
- Gordon J Hedley
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews , North Haugh, St Andrews, Fife KY16 9SS, U.K
| | - Arvydas Ruseckas
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews , North Haugh, St Andrews, Fife KY16 9SS, U.K
| | - Ifor D W Samuel
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews , North Haugh, St Andrews, Fife KY16 9SS, U.K
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36
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Yao Y, Xie X, Ma H. Ultrafast Long-Range Charge Separation in Organic Photovoltaics: Promotion by Off-Diagonal Vibronic Couplings and Entropy Increase. J Phys Chem Lett 2016; 7:4830-4835. [PMID: 27934051 DOI: 10.1021/acs.jpclett.6b02400] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The exciton dissociation in a model donor/acceptor heterojunction with electron-phonon couplings is simulated by a full quantum dynamical method, in which ultrafast long-range charge separation is observed. Such a novel scenario does not undergo short-range interfacial (pinned) charge transfer states, but can be mainly ascribed to the quantum resonance between local Frenkel excited states and a broad array of long-range charge transfer (LRCT) states assisted by the moderate off-diagonal vibronic couplings. The entropy-increasing effect associated with the very dense density of states for LRCT states is also found to be beneficial for lowering the free energy barrier for charge generation in organic solar cells.
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Affiliation(s)
- Yao Yao
- Department of Physics, South China University of Technology , Guangzhou 510640, China
| | - Xiaoyu Xie
- Key Laboratory of Mesoscopic Chemistry of MOE, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210023, China
| | - Haibo Ma
- Key Laboratory of Mesoscopic Chemistry of MOE, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210023, China
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37
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D'Avino G, Muccioli L, Castet F, Poelking C, Andrienko D, Soos ZG, Cornil J, Beljonne D. Electrostatic phenomena in organic semiconductors: fundamentals and implications for photovoltaics. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:433002. [PMID: 27603960 DOI: 10.1088/0953-8984/28/43/433002] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
This review summarizes the current understanding of electrostatic phenomena in ordered and disordered organic semiconductors, outlines numerical schemes developed for quantitative evaluation of electrostatic and induction contributions to ionization potentials and electron affinities of organic molecules in a solid state, and illustrates two applications of these techniques: interpretation of photoelectron spectroscopy of thin films and energetics of heterointerfaces in organic solar cells.
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Affiliation(s)
- Gabriele D'Avino
- Laboratory for the Chemistry of Novel Materials, Université de Mons, 7000 Mons, Belgium
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38
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Volpi R, Nassau R, Nørby MS, Linares M. Theoretical Study of the Charge-Transfer State Separation within Marcus Theory: The C60-Anthracene Case Study. ACS APPLIED MATERIALS & INTERFACES 2016; 8:24722-24736. [PMID: 27561228 DOI: 10.1021/acsami.6b06645] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We study, within Marcus theory, the possibility of the charge-transfer (CT) state splitting at organic interfaces and a subsequent transport of the free charge carriers to the electrodes. As a case study we analyze model anthracene-C60 interfaces. Kinetic Monte Carlo (KMC) simulations on the cold CT state were performed at a range of applied electric fields, and with the fields applied at a range of angles to the interface to simulate the action of the electric field in a bulk heterojunction (BHJ) interface. The results show that the inclusion of polarization in our model increases CT state dissociation and charge collection. The effect of the electric field on CT state splitting and free charge carrier conduction is analyzed in detail with and without polarization. Also, depending on the relative orientation of the anthracene and C60 molecules at the interface, CT state splitting shows different behavior with respect to both applied field strength and applied field angle. The importance of the hot CT in helping the charge carrier dissociation is also analyzed in our scheme.
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Affiliation(s)
- Riccardo Volpi
- Department of Physics, Chemistry and Biology (IFM), Linköping University , SE-581 83 Linköping, Sweden
- Swedish e-Science Research Centre (SeRC), Linköping University , SE-581 83 Linköping, Sweden
| | - Racine Nassau
- Department of Physics, Chemistry and Biology (IFM), Linköping University , SE-581 83 Linköping, Sweden
| | - Morten Steen Nørby
- Department of Physics, Chemistry and Biology (IFM), Linköping University , SE-581 83 Linköping, Sweden
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark , DK-5230 Odense M, Denmark
| | - Mathieu Linares
- Department of Physics, Chemistry and Biology (IFM), Linköping University , SE-581 83 Linköping, Sweden
- Swedish e-Science Research Centre (SeRC), Linköping University , SE-581 83 Linköping, Sweden
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39
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Li J, D'Avino G, Duchemin I, Beljonne D, Blase X. Combining the Many-Body GW Formalism with Classical Polarizable Models: Insights on the Electronic Structure of Molecular Solids. J Phys Chem Lett 2016; 7:2814-2820. [PMID: 27388926 DOI: 10.1021/acs.jpclett.6b01302] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We present an original hybrid QM/MM scheme merging the many-body Green's function GW formalism with classical discrete polarizable models and its application to the paradigmatic case of a pentacene crystal. Our calculated transport gap is found to be in excellent agreement with reference periodic bulk GW calculations, together with properly parametrized classical microelectrostatic calculations, and with photoionization measurements at crystal surfaces. More importantly, we prove that the gap is insensitive to the partitioning of pentacene molecules in QM and MM subsystems, as a result of the mutual compensation of quantum and classical polarizabilities, clarifying the relation between polarization energy and delocalization. The proposed hybrid method offers a computationally attractive strategy to compute the full spectrum of charged excitations in complex molecular environments, accounting for both QM and MM contributions to the polarization energy, a crucial requirement in the limit of large QM subsystems.
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Affiliation(s)
- Jing Li
- Grenoble Alpes University, CNRS, Institut NÉEL , F-38042 Grenoble, France
| | - Gabriele D'Avino
- Laboratory for Chemistry of Novel Materials, University of Mons , Place du Parc 20, BE-7000 Mons, Hainaut, Belgium
| | - Ivan Duchemin
- INAC, SP2M/L_Sim, CEA/UJF , Cedex 09, 38054 Grenoble, France
| | - David Beljonne
- Laboratory for Chemistry of Novel Materials, University of Mons , Place du Parc 20, BE-7000 Mons, Hainaut, Belgium
| | - Xavier Blase
- Grenoble Alpes University, CNRS, Institut NÉEL , F-38042 Grenoble, France
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