Intermolecular interactions triggered crystallization phase transition regulation for efficient and stable perovskite photovoltaics

Abstract

The efficiency of perovskite solar cells (PSCs) has witnessed remarkable improvements, yet the unbalanced δ-to-α phase crystallization transition dynamics and defects remain significant barriers to the reproducibility and stability of devices. Herein, we utilize the guanidine oxalate (GAOA) as ionic pair stabilizer to simultaneously regulate the crystallization dynamics and stabilize α-phase perovskite. The hydrogen bonds and bidentate chelation electrostatic interactions of GAOA and Pb-I framework effectively regulate the δ-to-α crystallization phase transition rate and restrict component loss during solvent evaporation. This strategy demonstrates broad applicability for the n-i-p and p-i-n structured PSCs with the champion power conversion efficiencies (PCEs) of 25.33% and 25.37%, respectively. Besides, the active area PCEs of modules are up to 21.97% for 37.9 cm2 and 19.25% for 641.4 cm2. Furthermore, the devices retain 93% of their initial efficiency for 1000 h and 95% for 500 h according to the ISOS-D-1 and ISOS-L-1 protocols.