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Sauvé G. Designing Alternative Non-Fullerene Molecular Electron Acceptors for Solution-Processable Organic Photovoltaics. CHEM REC 2019; 19:1078-1092. [PMID: 30663230 DOI: 10.1002/tcr.201800157] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 11/29/2018] [Indexed: 12/22/2022]
Abstract
Until recently, solution-processable organic photovoltaics (OPVs) mainly relied on fullerene derivatives as the n-type material, paired with a p-type conjugated polymer. However, fullerene derivatives have disadvantages that limit OPV performance, thus fueling research of non-fullerene acceptors (NFAs). Initially, NFAs showed poor performance due to difficulties in obtaining favorable blend morphologies. One example is our work with 2,6-dialkylamino core-substituted naphthalene diimides. Researchers then learned to control blend morphology by NFA molecular design. To limit miscibility with polymer while preventing excessive self-aggregation, non-planar, twisted or 3D structures were reported. An example of a 3D structure is our work with homoleptic zinc(II) complexes of azadipyrromethene. The most recent design is a planar A-D-A conjugated system where the D unit is rigid and has orthogonal side chains to control aggregation. These have propelled power conversion efficiencies (PCEs) to ∼14 %, surpassing fullerene-based OPVs. These exciting new developments prompt further investigations of NFAs and provide a bright future for OPVs.
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Affiliation(s)
- Geneviève Sauvé
- Department of Chemistry, Case Western Reserve University, 10900 Euclid Avenue, Cleveland OH, 44106
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Pal A, Wen LK, Jun CY, Jeon I, Matsuo Y, Manzhos S. Comparative density functional theory-density functional tight binding study of fullerene derivatives: effects due to fullerene size, addends, and crystallinity on band structure, charge transport and optical properties. Phys Chem Chem Phys 2018; 19:28330-28343. [PMID: 29034938 DOI: 10.1039/c7cp05290a] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
We present a systematic comparative density functional theory-density functional tight binding study of multiple derivatives of C60 and C70 with different addends, in molecular as well as solid state. In particular, effects due to fullerene size, type and number of addends, and of crystallinity on band structure, charge transport, and optical properties are investigated. These are important, in particular, for rational selection of fullerene derivatives as acceptor and electron transport layers in organic as well as planar inverted perovskite solar cells. We find that by the choice of type and number of addends, one can modulate the LUMO within 0.4 eV. Changes in the HOMO can reach 0.7 eV. Substituting C70 for C60 results in destabilization of the HOMO by about 0.1 eV for indene and quinodimethane addends and by a less significant amount for PCBM addends. The effect of C70-C60 substitution on the LUMO is of similar magnitude. A more significant change in HOMO-LUMO energy is seen for the aryl addends. On the other hand, all C70 based molecules have strong visible absorption. For most addends, the crystal packing leads to a stabilization of both the LUMO and HOMO by about ∼0.2 and ∼0.1 eV, respectively, vs. single molecules. When using bis-addends, it is also possible to enhance the visible absorption. Electron and hole transport rates are computed to vary vastly depending on the addends chosen; specifically, we compute that indene and quimodimethane addends can enhance charge transport rates while the aryl addend is predicted to result in substantially smaller mobilities of electrons and holes, vs. PC60BM. Furthermore, the -CH2 and bisaddend addition can significantly enhance the charge transfer rates for the PCBM addend.
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Affiliation(s)
- Amrita Pal
- Department of Mechanical Engineering, National University of Singapore, Block EA #07-08, 9 Engineering Drive 1, Singapore 117576, Singapore.
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Pelzer KM, Vázquez-Mayagoitia Á, Ratcliff LE, Tretiak S, Bair RA, Gray SK, Van Voorhis T, Larsen RE, Darling SB. Molecular dynamics and charge transport in organic semiconductors: a classical approach to modeling electron transfer. Chem Sci 2017; 8:2597-2609. [PMID: 28553494 PMCID: PMC5431633 DOI: 10.1039/c6sc04547b] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 01/03/2017] [Indexed: 11/21/2022] Open
Abstract
Organic photovoltaics (OPVs) are a promising carbon-neutral energy conversion technology, with recent improvements pushing power conversion efficiencies over 10%. A major factor limiting OPV performance is inefficiency of charge transport in organic semiconducting materials (OSCs). Due to strong coupling with lattice degrees of freedom, the charges form polarons, localized quasi-particles comprised of charges dressed with phonons. These polarons can be conceptualized as pseudo-atoms with a greater effective mass than a bare charge. We propose that due to this increased mass, polarons can be modeled with Langevin molecular dynamics (LMD), a classical approach with a computational cost much lower than most quantum mechanical methods. Here we present LMD simulations of charge transfer between a pair of fullerene molecules, which commonly serve as electron acceptors in OSCs. We find transfer rates consistent with experimental measurements of charge mobility, suggesting that this method may provide quantitative predictions of efficiency when used to simulate materials on the device scale. Our approach also offers information that is not captured in the overall transfer rate or mobility: in the simulation data, we observe exactly when and why intermolecular transfer events occur. In addition, we demonstrate that these simulations can shed light on the properties of polarons in OSCs. Much remains to be learned about these quasi-particles, and there are no widely accepted methods for calculating properties such as effective mass and friction. Our model offers a promising approach to exploring mass and friction as well as providing insight into the details of polaron transport in OSCs.
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Affiliation(s)
- Kenley M Pelzer
- Center for Nanoscale Materials , Argonne National Laboratory , 9700 Cass Ave., Lemont , IL 60439 , USA . ; Tel: +1-630-252-7020
- Materials Science Division , Argonne National Laboratory , 9700 Cass Ave, Lemont , IL 60439 , USA
| | - Álvaro Vázquez-Mayagoitia
- Argonne Leadership Computing Facility , Argonne National Laboratory , 9700 Cass Ave. , Lemont , IL 60439 , USA
| | - Laura E Ratcliff
- Argonne Leadership Computing Facility , Argonne National Laboratory , 9700 Cass Ave. , Lemont , IL 60439 , USA
| | - Sergei Tretiak
- Theoretical Division , Center for Nonlinear Studies , Center for Integrated Nanotechnologies , Los Alamos National Laboratory , Los Alamos , NM 87545 , USA
| | - Raymond A Bair
- Mathematics and Computer Science Division , Argonne National Laboratory , 9700 Cass Ave. , Argonne , IL 60439 , USA
- Computation Institute , University of Chicago , 5735 S. Ellis Ave. , Chicago , IL 60637 , USA
- Computer, Environment, and Life Sciences , Argonne National Laboratory , 9700 Cass Ave. , Lemont , IL 60439 , USA
| | - Stephen K Gray
- Center for Nanoscale Materials , Argonne National Laboratory , 9700 Cass Ave., Lemont , IL 60439 , USA . ; Tel: +1-630-252-7020
- Computation Institute , University of Chicago , 5735 S. Ellis Ave. , Chicago , IL 60637 , USA
| | - Troy Van Voorhis
- Department of Chemistry , Massachusetts Institute of Technology , 77 Massachusetts Ave , Cambridge , MA 02139 , USA
| | - Ross E Larsen
- Computational Science Center , National Renewable Energy Laboratory , 15301 Denver W. Parkway, Golden , CO 80401 , USA
| | - Seth B Darling
- Center for Nanoscale Materials , Argonne National Laboratory , 9700 Cass Ave., Lemont , IL 60439 , USA . ; Tel: +1-630-252-7020
- Institute for Molecular Engineering , University of Chicago , 5747 S. Ellis Ave. , Chicago , IL 60637 , USA
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Machado DFS, Lopes TO, Lima IT, da Silva Filho DA, de Oliveira HCB. Strong Solvent Effects on the Nonlinear Optical Properties of Z and E isomers from Azo-Enaminone Derivatives. J Phys Chem A 2016. [DOI: 10.1021/acs.jpca.6b01567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Zhou K, Zhang R, Liu J, Li M, Yu X, Xing R, Han Y. Donor/Acceptor Molecular Orientation-Dependent Photovoltaic Performance in All-Polymer Solar Cells. ACS APPLIED MATERIALS & INTERFACES 2015; 7:25352-25361. [PMID: 26528711 DOI: 10.1021/acsami.5b07605] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The correlated donor/acceptor (D/A) molecular orientation plays a crucial role in solution-processed all-polymer solar cells in term of photovoltaic performance. For the conjugated polymers PTB7-th and P(NDI2OD-T2), the preferential molecular orientation of neat PTB7-th films kept face-on regardless of the properties of processing solvents. However, an increasing content of face-on molecular orientation in the neat P(NDI2OD-T2) films could be found by changing processing solvents from chloronaphthalene (CN) and o-dichlorobenzene (oDCB) to chlorobenzene (CB). Besides, the neat P(NDI2OD-T2) films also exhibited a transformation of preferential molecular orientation from face-on to edge-on when extending film drying time by casting in the same solution. Consequently, a distribution diagram of molecular orientation for P(NDI2OD-T2) films was depicted and the same trend could be observed for the PTB7-th/P(NDI2OD-T2) blend films. By manufacture of photovoltaic devices with blend films, the relationship between the correlated D/A molecular orientation and device performance was established. The short-circuit current (Jsc) of devices processed by CN, oDCB, and CB enhanced gradually from 1.24 to 8.86 mA/cm(2) with the correlated D/A molecular orientation changing from face-on/edge-on to face-on/face-on, which could be attributed to facile exciton dissociation at D/A interface with the same molecular orientation. Therefore, the power conversion efficiency (PCE) of devices processed by CN, oDCB, and CB improved from 0.53% to 3.52% ultimately.
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Affiliation(s)
- Ke Zhou
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022, P. R. China
- University of the Chinese Academy of Sciences , No. 19A Yuquan Road, Beijing, 100049, P. R. China
| | - Rui Zhang
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022, P. R. China
- University of the Chinese Academy of Sciences , No. 19A Yuquan Road, Beijing, 100049, P. R. China
| | - Jiangang Liu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022, P. R. China
| | - Mingguang Li
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022, P. R. China
- University of the Chinese Academy of Sciences , No. 19A Yuquan Road, Beijing, 100049, P. R. China
| | - Xinhong Yu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022, P. R. China
| | - Rubo Xing
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022, P. R. China
| | - Yanchun Han
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022, P. R. China
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Sauvé G, Fernando R. Beyond Fullerenes: Designing Alternative Molecular Electron Acceptors for Solution-Processable Bulk Heterojunction Organic Photovoltaics. J Phys Chem Lett 2015; 6:3770-80. [PMID: 26722869 DOI: 10.1021/acs.jpclett.5b01471] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Organic photovoltaics (OPVs) are promising candidates for providing a low cost, widespread energy source by converting sunlight into electricity. Solution-processable active layers have predominantly consisted of a conjugated polymer donor blended with a fullerene derivative as the acceptor. Although fullerene derivatives have been the acceptor of choice, they have drawbacks such as weak visible light absorption and poor energy tuning that limit overall efficiencies. This has recently fueled new research to explore alternative acceptors that would overcome those limitations. During this exploration, one question arises: what are the important design principles for developing nonfullerene acceptors? It is generally accepted that acceptors should have high electron affinity, electron mobility, and absorption coefficient in the visible and near-IR region of the spectra. In this Perspective, we argue that alternative molecular acceptors, when blended with a conjugated polymer donor, should also have large nonplanar structures to promote nanoscale phase separation, charge separation and charge transport in blend films. Additionally, new material design should address the low dielectric constant of organic semiconductors that have so far limited their widespread application.
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Affiliation(s)
- Geneviève Sauvé
- Department of Chemistry, Case Western Reserve University , Cleveland, Ohio 44106, United States
| | - Roshan Fernando
- Department of Chemistry, Case Western Reserve University , Cleveland, Ohio 44106, United States
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Kubo Y, Nishiyabu R, James TD. Hierarchical supramolecules and organization using boronic acid building blocks. Chem Commun (Camb) 2015; 51:2005-20. [DOI: 10.1039/c4cc07712a] [Citation(s) in RCA: 118] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Current progress on hierarchical supramolecules using boronic acids has been highlighted in this feature article. The feasibility of the structure-directing ability is fully discussed from the standpoint of the generation of new smart materials.
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Affiliation(s)
- Yuji Kubo
- Department of Applied Chemistry
- Graduate School of Urban Environmental Sciences
- Tokyo Metropolitan University
- Hachioji
- Japan
| | - Ryuhei Nishiyabu
- Department of Applied Chemistry
- Graduate School of Urban Environmental Sciences
- Tokyo Metropolitan University
- Hachioji
- Japan
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