Hysteretic Behavior upon Light Soaking in Perovskite Solar Cells Prepared via Modified Vapor-Assisted Solution Process

Recently, the organic–inorganic hybrid perovskite solar cells exhibit rapidly rising efficiencies, while anomalous hysteresis in perovskite solar cells remains unsolvable. Herein, a high-quality perovskite thin film is prepared by a modified vapor-assisted solution process, which is a simple but well-controllable method proven to be capable of producing a thin film with full surface coverage and grain size up to micrometers. The as-fabricated perovskite solar cell has efficiency as high as 10.2%. The hysteresis effects of both planar and mesoscopic TiO<sub>2</sub>-based perovskite solar cells have been comprehensively studied upon illumination. The results demonstrate that mesoporous-based perovskite cells combined with remarkable grain size are subject to alleviating the hysteresis effects in comparison to the planar cells. Likewise, mesoscopic TiO<sub>2</sub>-based perovskite cells perform independently of illumination and bias conditions prior to the measurements, whereas the planar cells display a reversible behavior of illumination and applied bias-dependent I–V curves. The present study would refer strip road for the stability study of the perovskite solar cells.