Revealing the role of solvent additives in morphology and energy loss in benzodifuran polymer-based non-fullerene organic solar cells

作者：Zheng, Zhi; He, Enfang; Wang, Jie; Qin, Zhaotong; Niu, Tianqi; Guo, Fengyun; Gao, Shiyong; Ma, Zaifei; Zhao, Liancheng; Lu, Xinhui; Xue, Qifan; Cao, Yong; Mola, Genene Tessema; Zhang, Yong^*

来源：Journal of Materials Chemistry A, 2021, 9(46): 26105-26112.

DOI：10.1039/d1ta08893a

• CIRCUIT VOLTAGE LOSSES
• BULK-HETEROJUNCTION
• PROCESSING ADDITIVES
• EFFICIENCY ENHANCEMENT
• PHASE-SEPARATION
• J-AGGREGATION
• PERFORMANCE
• ACCEPTORS

Solvent additive (SA) treatment is the most effective strategy to obtain highly efficient non-fullerene organic solar cells (NF-OSCs). However, NF-OSCs from SA treatment usually exhibit different or even opposite effects on photovoltaic performance compared with fullerene-based OSCs. Despite the rapid progress in NF-OSCs from SA treatment, the working mechanism of SAs in the morphological optimization of NF-OSCs and their role in affecting the photovoltaic performance are still controversial, and systematic investigations are needed. In this work, two kinds of SA, non-aromatic solvent additives (NSA: DIO, DBrO) and aromatic solvent additives (ASA: DPE, CN), were applied to the benzo[1,2-b:4,5-b ']difuran-based polymer PBDF-BDD and non-fullerene acceptor IT-4F to systemically investigate their effects on photovoltaic performance and their roles in the open-circuit voltage (V-oc) and fill factor (FF). The SAs have a positive impact on the power conversion efficiencies of NF-OSCs, but completely opposite trends of V-oc and FF were observed for NF-OSCs processed with NSAs and ASAs. The devices with NSA obtained higher FF than devices with ASA. However, the NSA-added devices exhibited a V-oc drop of about 0.1 V with a large energy loss (E-loss); in contrast, devices with ASAs showed minor change on V-oc and thereby on E-loss. Further investigations indicated that NSA and ASA have different effects on inducing the crystallization of either PBDF-BDD or IT-4F, resulting in different donor/acceptor interactions and interfaces, thus producing the changes in E-g, E-CT and energetic disorder, which were further investigated through GIWAXS and energy loss mechanism.

• 单位
  郑州大学; y