24.96%-Efficiency FACsPbI3 Perovskite Solar Cells Enabled by an Asymmetric 1,3-Thiazole-2,4-Diammonium

Surmounting complicated defects at the electron transport layer (ETL) and perovskite interface plays a non-trivial role in improving efficiency and stability of perovskite solar cells (PSCs). Herein, an asymmetric interface modification strategy (AIMS) is developed to passivate the defects from both a SnO2 ETL and the perovskite buried surface via incorporating 1,3-thiazole-2,4-diammonium (TDA) into the SnO2/perovskite interface. Detailed experimental and calculated results demonstrate that N3 (the nitrogen atom bonding to the imine) in the TDA preferentially cures the free hydroxyl (-OH), oxygen vacancy (V-O), and the Sn-related defects on the SnO2 surface, while N1 (the nitrogen atom bonding to the vinyl) is more inclined to passivate the Pb2+ and I- related defects at the perovskite buried surface. As a result, the TDA-modified FACsPbI(3) PSC yields a champion power conversion efficiency (PCE) of 24.96% with a gratifying open-circuit voltage (V-oc) of 1.20 V. In addition, the optimized PSCs exhibit charming air-operational stability with the unencapsulated device sustaining 97.04% of its initial PCE after storage in air conditions for 1400 h. The encapsulated device maintains 90.21% of its initial PCE after maximum power point tracking for 500 h.

Automated summary

Surmounting complicated defects at ETL and perovskite interface is crucial for enhancing efficiency and stability of PSCs. An asymmetric interface modification strategy (AIMS) is developed, incorporating 1,3-thiazole-2,4-diammonium (TDA), to passivate defects on both SnO2 ETL and perovskite buried surface. TDA with nitrogen atoms (N3 and N1) in the structure selectively cures different types of defects, resulting in a champion PCE of 24.96% and remarkable operational stability.