Post-Deposition Vapor Annealing Enables Fabrication of 1 cm(2) Lead-Free Perovskite Solar Cells

Abstract

Sn-based perovskite solar cells (PSCs) are promising alternatives to replacing toxic Pb-based PSCs, which have shown a rapid rise in photovoltaic applications in the past 1 year. However, the reported Sn-based PSCs are often fabricated with a small aperture area (typically 0.02-0.1 cm(2)) because forming homogeneous pinhole-free continuous films over a large surface area is still challenging. Herein, a post-deposition vapor annealing (PDVA) process assisted by methylammonium chloride vapor is presented that enables the fabrication of stable, homogeneous pinhole-free FASnI(3) perovskite absorber films with low crystal defects and low surface recombination over a relatively large area up to 1.02 cm(2). Inverted planar solar cells fabricated with a 1.02 cm(2) aperture area show a maximum power conversion efficiency of 6.33% with high reproducibility and stability. The shelf-lifetime stability test shows that the PSCs retain 90% of their performance for more than 1000 h when stored in a N-2-filled glove box and under dark conditions. The preliminary light-soaking stability tests under continuous illumination and maximum power-tracking conditions are relatively promising. This study marks an important step toward the up scaling of Sn-based PSCs.