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Highly Efficient All‐Small‐Molecule Organic Solar Cells with Appropriate Active Layer Morphology by Side Chain Engineering of Donor Molecules and Thermal Annealing
Author(s) -
Qiu Beibei,
Chen Zeng,
Qin Shucheng,
Yao Jia,
Huang Wenchao,
Meng Lei,
Zhu Haiming,
Yang Yang Michael,
Zhang ZhiGuo,
Li Yongfang
Publication year - 2020
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201908373
Subject(s) - materials science , organic solar cell , side chain , alkyl , acceptor , active layer , molecule , small molecule , conjugated system , thiophene , annealing (glass) , polymer solar cell , chemical engineering , photochemistry , substituent , polymer , energy conversion efficiency , organic chemistry , nanotechnology , layer (electronics) , chemistry , optoelectronics , composite material , thin film transistor , biochemistry , physics , engineering , condensed matter physics
Abstract It is very important to fine‐tune the nanoscale morphology of donor:acceptor blend active layers for improving the photovoltaic performance of all‐small‐molecule organic solar cells (SM‐OSCs). In this work, two new small molecule donor materials are synthesized with different substituents on their thiophene conjugated side chains, including SM1‐S with alkylthio and SM1‐F with fluorine and alkyl substituents, and the previously reported donor molecule SM1 with an alkyl substituent, for investigating the effect of different conjugated side chains on the molecular aggregation and the photophysical, and photovoltaic properties of the donor molecules. As a result, an SM1‐F‐based SM‐OSC with Y6 as the acceptor, and with thermal annealing (TA) at 120 °C for 10 min, demonstrates the highest power conversion efficiency value of 14.07%, which is one of the best values for SM‐OSCs reported so far. Besides, these results also reveal that different side chains of the small molecules can distinctly influence the crystallinity characteristics and aggregation features, and TA treatment can effectively fine‐tune the phase separation to form suitable donor–acceptor interpenetrating networks, which is beneficial for exciton dissociation and charge transportation, leading to highly efficient photovoltaic performance.