A Top‐Down Strategy to Engineer ActiveLayer Morphology for Highly Efficient and Stable All‐Polymer Solar Cells

• DOI: 10.1002/adma.202202608
• Publication Date: 2022-06-24T07:53:41Z
• Authors: Huiting Fu; Zhengxing Peng; Qunping Fan; Francis R. Lin; Feng Qi; Yixin Ran; Ziang Wu; Baobing Fan; Kui Jiang; Han Young Woo; Guanghao Lu; Harald Ade; Alex K.‐Y. Jen
• Keywords: Morphology

A major challenge hindering the further development of all-polymer solar cells (all-PSCs) employing polymerized small-molecule acceptors is relatively low fill factor (FF) due to difficulty in controlling active-layer morphology. The issues typically arise from oversized phase separation resulting thermodynamically unfavorable mixing between two macromolecular species, and disordered molecular orientation/packing highly anisotropic polymer chains. Herein, a facile top-down strategy engineer morphology blends developed by leveraging layer-by-layer (LBL) deposition. Optimal intermixing components can be achieved two-step process tuning bottom-layer swelling during top-layer Consequently, both bottom layer ordering top optimized with suitable processing solvent. favorable gradient vertical composition distribution for efficient charge transport extraction therefore realized, affording high all-PSC efficiency 17.0% FF 76.1%. derived devices also possess excellent long-term thermal stability retain >90% their initial efficiencies after being annealed at 65 °C 1300 h. These results validate distinct advantages an LBL protocol fabricate high-performance all-PSCs.