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Title: Intra-molecular Charge Transfer and Electron Delocalization in Non-fullerene Organic Solar Cells

Abstract

Two types of electron acceptors were synthesized by coupling two kinds of electron-rich cores with four equivalent perylene diimides (PDIs) at the a position. With fully aromatic cores, TPB and TPSe have pi-orbitals spread continuously over the whole aromatic conjugated backbone, unlike TPC and TPSi, which contain isolated PDI units due to the use of a tetrahedron carbon or silicon linker. Density functional theory calculations of the projected density of states showed that the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) for TPB are localized in separate regions of space. Further, the LUMO of TPB shows a greater contribution from the orbitals belonging to the connective core of the molecules than that of TPC. Overall, the properties of the HOMO and LUMO point at increased intra-molecular delocalization of negative charge carriers for TPB and TPSe than for TPC and TPSi and hence at a more facile intra-molecular charge transfer for the former. The film absorption and emission spectra showed evidences for the inter -molecular electron delocalization in TPB and TPSe, which is consistent with the network structure revealed by X-ray diffraction studies on single crystals of TPB. These features benefit the formation of charge transfer statesmore » and/or facilitate charge transport. Thus, higher electron mobility and higher charge dissociation probabilities under J(sc) condition were observed in blend films of TPB:PTB7-Th and TPSe:PTB7-Th than those in TPC:PTB7Th and TPSi:PTB7-Th blend films. As a result, the J(sc) and fill factor values of 15.02 mA/cm(2), 0.58 and 14.36 mA/cm(2), 0.55 for TPB- and TPSe-based solar cell are observed, whereas those for TPC and TPSi are 11.55 mA/cm2, 0.47 and 10.35 mA/cm(2), 0.42, respectively.« less

Authors:
ORCiD logo [1];  [2]; ORCiD logo [3]; ORCiD logo [2]; ORCiD logo [2];  [4]; ORCiD logo [2]; ORCiD logo [4]; ORCiD logo [4];  [4];  [2]
  1. Department of Chemistry, Key Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong Province, Shantou University, Guangdong 515063, P. R. China
  2. Department of Chemistry, The James Franck Institute, The University of Chicago, 929 E 57th Street, Chicago, Illinois 60637, United States
  3. Institute for Molecular Engineering, The University of Chicago, 5747 South Ellis Avenue, Chicago, Illinois 60637, United States
  4. Institute for Molecular Engineering, Materials Science Division, Argonne National Laboratory, 9700 Cass Avenue, Lemont, Illinois 60439, United States; Institute for Molecular Engineering, The University of Chicago, 5747 South Ellis Avenue, Chicago, Illinois 60637, United States
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1433912
DOE Contract Number:
AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: ACS Applied Materials and Interfaces; Journal Volume: 10; Journal Issue: 12
Country of Publication:
United States
Language:
English
Subject:
electron delocalization; intra-molecular charge transfer; non-fullerene electron acceptor; organic solar cell; perylene diimide

Citation Formats

Wu, Qinghe, Zhao, Donglin, Goldey, Matthew B., Filatov, Alexander S., Sharapov, Valerii, Colón, Yamil J., Cai, Zhengxu, Chen, Wei, de Pablo, Juan, Galli, Giulia, and Yu, Luping. Intra-molecular Charge Transfer and Electron Delocalization in Non-fullerene Organic Solar Cells. United States: N. p., 2018. Web. doi:10.1021/acsami.7b18717.
Wu, Qinghe, Zhao, Donglin, Goldey, Matthew B., Filatov, Alexander S., Sharapov, Valerii, Colón, Yamil J., Cai, Zhengxu, Chen, Wei, de Pablo, Juan, Galli, Giulia, & Yu, Luping. Intra-molecular Charge Transfer and Electron Delocalization in Non-fullerene Organic Solar Cells. United States. doi:10.1021/acsami.7b18717.
Wu, Qinghe, Zhao, Donglin, Goldey, Matthew B., Filatov, Alexander S., Sharapov, Valerii, Colón, Yamil J., Cai, Zhengxu, Chen, Wei, de Pablo, Juan, Galli, Giulia, and Yu, Luping. Fri . "Intra-molecular Charge Transfer and Electron Delocalization in Non-fullerene Organic Solar Cells". United States. doi:10.1021/acsami.7b18717.
@article{osti_1433912,
title = {Intra-molecular Charge Transfer and Electron Delocalization in Non-fullerene Organic Solar Cells},
author = {Wu, Qinghe and Zhao, Donglin and Goldey, Matthew B. and Filatov, Alexander S. and Sharapov, Valerii and Colón, Yamil J. and Cai, Zhengxu and Chen, Wei and de Pablo, Juan and Galli, Giulia and Yu, Luping},
abstractNote = {Two types of electron acceptors were synthesized by coupling two kinds of electron-rich cores with four equivalent perylene diimides (PDIs) at the a position. With fully aromatic cores, TPB and TPSe have pi-orbitals spread continuously over the whole aromatic conjugated backbone, unlike TPC and TPSi, which contain isolated PDI units due to the use of a tetrahedron carbon or silicon linker. Density functional theory calculations of the projected density of states showed that the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) for TPB are localized in separate regions of space. Further, the LUMO of TPB shows a greater contribution from the orbitals belonging to the connective core of the molecules than that of TPC. Overall, the properties of the HOMO and LUMO point at increased intra-molecular delocalization of negative charge carriers for TPB and TPSe than for TPC and TPSi and hence at a more facile intra-molecular charge transfer for the former. The film absorption and emission spectra showed evidences for the inter -molecular electron delocalization in TPB and TPSe, which is consistent with the network structure revealed by X-ray diffraction studies on single crystals of TPB. These features benefit the formation of charge transfer states and/or facilitate charge transport. Thus, higher electron mobility and higher charge dissociation probabilities under J(sc) condition were observed in blend films of TPB:PTB7-Th and TPSe:PTB7-Th than those in TPC:PTB7Th and TPSi:PTB7-Th blend films. As a result, the J(sc) and fill factor values of 15.02 mA/cm(2), 0.58 and 14.36 mA/cm(2), 0.55 for TPB- and TPSe-based solar cell are observed, whereas those for TPC and TPSi are 11.55 mA/cm2, 0.47 and 10.35 mA/cm(2), 0.42, respectively.},
doi = {10.1021/acsami.7b18717},
journal = {ACS Applied Materials and Interfaces},
number = 12,
volume = 10,
place = {United States},
year = {Fri Mar 02 00:00:00 EST 2018},
month = {Fri Mar 02 00:00:00 EST 2018}
}