Amino-acid-type alkylamine additive for high-performance wide-bandgap perovskite solar cells

A wide-bandgap (WBG) perovskite top component cell is vital for all perovskite-based tandem solar cells. However, such WBG perovskite solar cell (PSC) suffers from inferior crystallinity, huge voltage loss and poor photostability. Herein, we report a amino-acid-type alkylamine, 5-aminolevulinic acid hydrochloride (ALH) additive to address these issues to enhance the performance of WBG PSCs. It is found that the ALH effectively modulates the perovskite crystallization via chemical complexation between the ALH and PbI2, and enhances the crystallinity of the perovskite film. Moreover, the amino acid ALH not only passivates negatively charged deep-level IFA and IPb anti-site defects via –NH3+ terminals to reduce voltage loss, but also suppresses photo-induced phase segregation via the coordination between –COO− groups and halide vacancies. With these merits, the ALH-based PSC delivers an excellent power-conversion efficiency (PCE) of 21.13%, one of the highest values for inverted WBG PSCs. In addition, the air and thermal stability are also significantly improved. Our findings provide a feasible approach to prepare highly efficient and stable WBG PSCs.