A Refined Bulk P–I–N Structure in All-Polymer Solar Cells To Achieve 20.1% Efficiency and Improved Stability
Jinge Zhu, Rui Zeng, Erjun Zhou, Chao Li, Jiawei Deng, Mengzhen Du, Qing Guo, Mengwei Ji, Zongtao Wang, Lin Yi, Fei Han, Jiaxin Zhuang, Senke Tan, Lixuan Kan, Lei Zhu, Ming Zhang, Feng Liu
Abstract
All-polymer solar cells (all-PSCs) have shown good potential for achieving balanced power conversion efficiency (PCE) and operational stability. However, precise control of the morphology remains challenging. Here, we constructed a bulk p–i–n structure with a regulated i-region by incorporating a shamrock-shaped nonfullerene acceptor, AQI4. This ternary formulation resulted in optimized energy-level stairing, enhanced exciton dissociation, and reduced energy loss. In blended thin film fabrication, a binary solvent of chlorobenzene (CB):o-xylene (OXY) was used, which enhanced the crystallization of the polymers and formed a high-density fibril network. The i-region width was reduced to less than 2 nm. This structural refinement enabled efficient charge transport through tie-chains between polymer crystallizations, thereby suppressing charge recombination. As a result, the organic solar cell (OSC) devices achieved a PCE of 20.1% (certified as 19.5%) and retained good stability. The T 80 lifetime of over 1800 h in the OSC structure was recorded. Notably, the binary solvent CB:OXY also contributed to a feasible printing fabrication; the 18.4 cm 2 OSC mini-modules achieved a PCE of 16.5%. Our results suggest that the shape of the guest molecule may be a key point to modulate the bulk p–i–n structure and improve the performance of all-PSCs.