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High‐Performance Ternary Polymer Solar Cells Enabled by a New Narrow Bandgap Nonfullerene Small Molecule Acceptor with a Higher LUMO Level
Author(s) -
Su Dan,
Li Kun,
Liu Wanru,
Zhang Weichao,
Li Xiaofang,
Wu Yishi,
Shen Fugang,
Huo Shuying,
Fu Hongbing,
Zhan Chuanlang
Publication year - 2020
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.202000393
Subject(s) - homo/lumo , ternary operation , acceptor , band gap , organic solar cell , materials science , energy conversion efficiency , thiophene , open circuit voltage , conjugated system , molecule , chemistry , polymer , optoelectronics , physics , voltage , organic chemistry , computer science , quantum mechanics , composite material , programming language , condensed matter physics
Obtaining a large open‐circuit voltage ( V OC ) and high short‐circuit current density ( J SC ) simultaneously is important in improving power conversion efficiency (PCE) of organic photovoltaics. The ternary strategy with using a higher lowest unoccupied molecular orbital (LUMO) level nonfullerene acceptor (NFA) guest can achieve increased V OC , yet J SC is decreased or maintained, so it's still a challenge to offer increased V OC and J SC values concurrently via the newly presented V OC ‐increased ternary strategy. To overcome this issue, a new narrow bandgap NFA TT‐S‐4F is reported by introducing 3,6‐dimethoxylthieno[3,2‐b]thiophene (TT) as π‐spacers to connect electron‐rich core with terminal groups, so as to upshift the LUMO level and extend π‐system. When adding 10% TT‐S‐4F into binary system based on PTB7‐Th:IEICO‐4F, the higher‐LUMO‐level of TT‐S‐4F, the increased charge mobilities, the reduced trap‐assisted combination loss, and a finer nanofiber structure and increased phase separation size are obtained, which simultaneously promotes J SC , V OC , and fill factor (FF), thus obtaining an optimal PCE (12.5% vs 11.5%). This work illustrates that an extending conjugated backbone with large π‐spacers and inclusion of alkylthiophenyl side‐chains is a concept to synthesize NFA guests for use on the V OC ‐increased ternary strategy that enables to realize simultaneously increased J SC , V OC , and FF.