All-Small-Molecule Organic Solar Cells with Efficiency Approaching 16% and FF over 80%
By:
Meng, LX (Meng, Lingxian) [1] , [2] , [3] ;
Li, MP (Li, Mingpeng) [1] , [2] , [3] ;
Lu, GY (Lu, Guanyu) [4] ;
Shen, ZC (Shen, Zichao) [4] ;
Wu, SM (Wu, Simin) [1] , [2] , [3] ;
Liang, HZ (Liang, Huazhe) [1] , [2] , [3] ;
Li, ZX (Li, Zhixiang) [1] , [2] , [3] ;
Lu, GH (Lu, Guanghao) [4] ;
Yao, ZY (Yao, Zhaoyang) [1] , [2] , [3] ;
Li, CX (Li, Chenxi) [1] , [2] , [3] ;
Wan, XJ (Wan, Xiangjian) [1] , [2] , [3] ;
Chen, YS (Chen, Yongsheng) [1] , [2] , [3]
SMALL, 2022,
Article Number 2201400
DOI
10.1002/smll.202201400
Abstract
Molecule engineering has been demonstrated as a valid strategy to adjust the active layer morphology in all-small-molecule organic solar cells (ASM-OSCs). In this work, two non-fullerene acceptors (NFAs), FO-2Cl and FO-EH-2Cl, with different alkyl side chains are reported and applied in ASC-OSCs. Compared with FO-2Cl, FO-EH-2Cl is designed by replacing the octyl alkyl chains with branched iso-octyl alkyl chains, leading to an enhanced molecular packing, crystallinity, and redshifted absorption. With a small molecule BSFTR as donor, the device of BSFTR:FO-EH-2Cl obtains a better morphology and achieves a higher power conversion efficiency (PCE) of 15.78% with a notable fill factor (FF) of 80.44% than that of the FO-2Cl-based device with a PCE of 15.27% and FF of 78.41%. To the authors' knowledge, the FF of 80.44% is the highest value in ASM-OSCs. These results demonstrate a good example of fine-tuning the molecular structure to achieve suitable active layer morphology with promising performance for ASM-OSCs, which can provide valuable insight into material design for high-efficiency ASM-OSCs.
