Solvent engineering for high efficiency and stability of 2D/3D perovskite solar cells

The strategy of fabricating 2D metal halide perovskites on the 3D perovskite is an effective way to improve the performance of perovskite solar cells (PSCs). However, the large-scale preparation of 2D perovskite with high phase purity and controllable film thickness is challenging. In a recent issue of Science, Mohite et al. leverage the dielectric constant and Gutmann donor number to select the solvent of 2D perovskite for the desired 2D/3D perovskite bilayer, resulting in a power conversion efficiency (PCE) of 24.5%, with excellent stability of T99 (time required to preserve 99% of initial photovoltaic efficiency) of > 2,000 h for the PSC device.