A novel hole extraction layer to enhance the performance of inverted organic solar cells

作者:Qin, Dashan; Cao, Huan; Yan, Cenqi; Meng, Shuai-Shuai; Tang, Jian-Xin; Zhan, Xiaowei*
来源:Journal of Materials Chemistry A, 2017, 5(48): 25385-25390.
DOI:10.1039/c7ta08694f

摘要

Polyethylenimine ethoxylated (PEIE) is a classical cathode-modifying material. Here, we report the first example of using PEIE as an anode-modifying material. We use MoO3/PEIE/Ag as a hole extraction layer to enhance the performance of inverted organic solar cells (OSCs). The introduction of an ultrathin PEIE interlayer can markedly reduce the anodic resistance of inverted devices, mostly because the ultrathin PEIE interlayer can separate MoO3 from Ag, thereby suppressing the reduction of MoO3 by gaseous Ag to lower-oxidation state Mo species which decrease the work function of MoO3 and are then detrimental to hole extraction from the photoactive layer. In addition, the PEIE interlayer can act as an optical spacer to optimize the optical absorption of inverted devices. As a result, the novel hole extraction structure of MoO3/PEIE/Ag increases device efficiency by a factor of 16% relative to conventional MoO3/Ag in inverted OSCs.