期刊
ADVANCED MATERIALS
卷 30, 期 2, 页码 -出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/adma.201704713
关键词
fused-ring electron acceptors; naphthodithiophene; nonfullerene acceptors; organic solar cells
类别
资金
- National Natural Science Foundation of China (NSFC) [91433114, 21734001]
- NSFC [21504058, 21504066, 21534003]
- National Science Foundation (NSF) [DMR-1507249, CBET-1639429]
- Ministry of Science and Technology of China [2016YFA0200700]
- U.S. Department of Energy [DE-AC02-05CH11231]
Naphtho[1,2-b: 5,6-b'] dithiophene is extended to a fused octacyclic building block, which is end capped by strong electron-withdrawing 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene) malononitrile to yield a fused-ring electron acceptor (IOIC2) for organic solar cells (OSCs). Relative to naphthalene-based IHIC2, naphthodithiophene-based IOIC2 with a larger p-conjugation and a stronger electron-donating core shows a higher lowest unoccupied molecular orbital energy level (IOIC2: -3.78 eV vs IHIC2: -3.86 eV), broader absorption with a smaller optical bandgap (IOIC2: 1.55 eV vs IHIC2: 1.66 eV), and a higher electron mobility (IOIC2: 1.0 x 10(-3) cm(2) V-1 s(-1) vs IHIC2: 5.0 x 10(-4) cm(2) V-1 s(-1)). Thus, IOIC2-based OSCs show higher values in open-circuit voltage, short-circuit current density, fill factor, and thereby much higher power conversion efficiency (PCE) values than those of the IHIC2-based counterpart. In particular, as-cast OSCs based on FTAZ: IOIC2 yield PCEs of up to 11.2%, higher than that of the control devices based on FTAZ: IHIC2 (7.45%). Furthermore, by using 0.2% 1,8-diiodooctane as the processing additive, a PCE of 12.3% is achieved from the FTAZ: IOIC2-based devices, higher than that of the FTAZ: IHIC2-based devices (7.31%). These results indicate that incorporating extended conjugation into the electron-donating fused-ring units in nonfullerene acceptors is a promising strategy for designing high-performance electron acceptors.
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