Low-Temperature Soft-Cover-Assisted Hydrolysis Deposition of Large-Scale TiO₂ Layer for Efficient Perovskite Solar...

Perovskite solar cells with TiO₂ electron transport layers exhibit power conversion efficiency (PCE) as high as 22.7% in single cells. However, the preparation process of the TiO₂ layer is adopted by an unscalable method or requires high-temperature sintering, which precludes its potential use for mass production of flexible devices. In this study, a scalable low-temperature soft-cover-assisted hydrolysis (SAH) method is presented, where the precursor solution is sandwiched between a soft cover and preheated substrate to form a closed hydrolysis environment. Compact homogeneous TiO₂ films with a needle-like structure were obtained after the hydrolysis of a TiCl₄ aqueous solution. Moreover, by careful optimization of the TiO₂ fabrication conditions, a high PCE of 14.01% could be achieved for a solar module (4 × 4 cm²) prepared using the SAH method. This method provides a novel approach for the efficient scale-up of the low-temperature TiO₂ film growth for industrial applications.