Combining Fused‐Ring and Unfused‐Core Electron Acceptors Enables Efficient Ternary Organic Solar Cells with Enhanced Fill Factor and Broad Compositional Tolerance

• DOI: 10.1002/solr.201900317
• Publication Date: 2019-08-26T23:08:58Z
• Authors: Lingling Zhan; Shuixing Li; Shuhua Zhang; Tsz-Ki Lau; Thomas Rieks Ande...; Xinhui Lu; Minmin Shi; Chang-Zhi Li; Gang Li; Hongzheng Chen
• Keywords: Acceptor; Open-circuit voltage; Electron acceptor

The ternary blend strategy has shown great potential to improve the photovoltaic performance of organic solar cells (OSCs). Usually, adopting two acceptors with similar chemical structures shows good compatibility but limited enhancement in performance, whereas different always a compositional sensitivity issue. Herein, highly efficient OSC an enhanced fill factor (FF) and broad tolerance is demonstrated by introducing fused‐ring acceptor IT‐M binary based on unfused‐core HC‐PCIC polymer donor PBDB‐TF. Detailed studies optical, electrical, morphological properties blends reveal process charge dynamics work mechanisms device. It found that addition into PBDB‐TF:HC‐PCIC not only adapts parallel‐like model, also optimizes morphology domain sizes blend, resulting reduced trap‐assisted recombination suppressed bimolecular recombination. Consequently, open‐circuit voltage ( V oc ), short‐circuit current density J sc FF are synergistically enhanced, leading improved power conversion efficiency (PCE) 12.34% high 0.88 V, increased 18.69 mA cm −2 , 73.82% for device 5% content. Moreover, PCEs OSCs remain above 11% within ratio 2.5–50%, exhibiting tolerance, which rarely reported fullerene‐free OSCs.