Crystallization modulation of methylammonium-free narrow-bandgap perovskite for thermal-stable all-perovskite tandem solar modules
- Han Gao
- Jie Wen
- Siyang Zhao
- Manya Li
- Shuncheng Yang
- Hongfei Sun
- Chenshuaiyu Liu
- Siyu Xia
- Khoa Nguyen
- Pu Wu
- Yijia Guo
- Runnan Liu
- Dong Zhou
- Chenyang Duan
- Ke Xiao
- Ludong Li
- Peng Cui
- Daniel H. Macdonald
- Jin Xie
- Jian Xu
- Renxing Lin
- Hairen Tan
2026-04-29
All-perovskite tandem solar modules offer the potential to achieve rapid increases in power conversion efficiency (PCE), yet efficient lead-tin (Pb-Sn) subcells often contain thermally unstable methylammonium (MA). Replacing MA with cesium (Cs) has been adopted to improve thermal stability but results in nonuniform nucleation and rapid crystallization, degrading large-area film quality. Here, we introduce p-π conjugated semicarbazide hydrochloride (SHCl) as a crystallization modifier in precursor solutions. The SH + and Cl − ions synergistically modulate the precipitation of Cs components and the growth process of perovskite films, achieving homogeneous nucleation and retarded crystal growth in formamidinium-cesium (FACs)–based Pb-Sn perovskites. Single-junction FACs Pb-Sn devices retained 85% of the initial efficiency after 700 hours at 85°C. The resultant all-perovskite tandem modules (20.25 square centimeters) achieved the certified PCE of 24.3%, representing the highest certified PCE among MA-free all-perovskite tandem modules. Encapsulated modules maintained 90 and 92% of their initial efficiency under ISOS-standardized damp heat (200 hours) and thermal cycling (200 cycles) tests, respectively.