Nature Energy, Published online: 20 October 2026; doi:10.1038/s41560-026-02148-w

Cathode interlayers play a pivotal role in improving the performance of organic solar cells. Yao, Zhang, Zhang, Wang et al. show a stepwise solvent treatment to achieve a vertically aligned cathode interlayer, enabling a certified efficiency of 20.65% in binary organic solar cells.