期刊
MATERIALS CHEMISTRY FRONTIERS
卷 4, 期 6, 页码 1729-1738出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/c9qm00754g
关键词
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资金
- Shen Zhen Technology and Innovation Commission [JCYJ20170413173814007, JCYJ20170818113905024]
- Hong Kong Research Grants Council [R6021-18, 16305915, 16322416, 606012, 16303917]
- Hong Kong Innovation and Technology Commission [ITC-CNERC14SC01, ITS/471/18]
- ONR [N000141712204]
- Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy [DE-AC02-05CH11231]
Core engineering of small molecule acceptors (SMAs) is crucially important for enhancing device efficiency for nonfullerene organic solar cells (NF-OSCs). The most commonly used SMAs (e.g., ITIC) utilize indacenodithieno[3,2-b]thiophene (IDTT) as the central core, which has restricted their absorption ranges due to the weak electron-donating ability and short conjugation length. Here, we fused two electron-rich units, namely cyclopenta[2,1-b:3,4-b ']dithiophene (CPDT) and dithieno[3,2-b:2 ',3 '-d]pyran (DTPR), into the cores for constructing low-bandgap SMAs. The resulting CPDT-4Cl and DTPR-4Cl molecules exhibit extended nonacyclic central cores and strengthened intramolecular transfer (ICT) effect, resulting in red-shifted absorption (up to similar to 950 nm) and up-shifted HOMO levels compared with IDTT-4Cl. Consequently, the NF-OSCs based on PTB7-Th:CPDT-4Cl and PTB7-Th:DTPR-4Cl achieved higher PCEs of 12.15% and 10.75%, respectively, than those of the PTB7-Th:IDTT-4Cl ones (7.70%). Notably, high short-circuit current densities (J(SC)) of 23-25 mA cm(-2) were obtained by the CPDT-4Cl and DTPR-4Cl-based devices, indicating the great potential of the electron-donating CPDT and DTPR as promising building blocks to construct high-performance low-bandgap SMAs.
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