Synergistic preheating and moderate temperature liquid medium annealing for high performance perovskite solar cells

Abstract

The performance and stability of perovskite solar cells (PSCs) can be limited by film quality and interfacial defects. In this study, we developed a moderate-temperature liquid medium annealing (LMA) process that involves a 20-s preheating step, followed by formamidinium bromide (FABr) passivation. The preheating step effectively removes residual antisolvent and initiates uniform nucleation, enabling the formation of continuous and uniform perovskite films with large grains and high crystallinity. The optimal time and temperature for LMA were determined to be 3 min and 50 °C, respectively. Devices fabricated through LMA involving the preheating step exhibited a champion power conversion efficiency (PCE) of 21.49% and suppressed hysteresis. Incorporation of FABr passivation into this process improved the PCE to 22.01%, reduced the trap density between perovskite and the hole transport material, and extended carrier lifetime. Notably, an unencapsulated PSC with perovskite films produced through LMA, preheating, and FABr passivation retained 94.5% of its initial PCE after 650 h under ISOS-D1 testing. Overall, the proposed synergistic strategy offers a scalable route for fabricating efficient and durable PSCs.