High-quality perovskite films prepared by nucleus epitaxial growth for efficient and stable perovskite solar cells

The quality of perovskite films is influenced by the crystal growth process and determines the performance and stability of perovskite solar cells. The incongruous atomic dispersion of nucleation during the crystallization process is one of the main causes of the degradation of the performance and stability of perovskite solar cells. In this study, we employed nucleus-induced epitaxial growth to improve the quality of perovskite films. In doing so, delta-FAPbI(3) was introduced into a PbI2 precursor solution to induce the epitaxial growth of perovskite using the delta-phase lattice. Perovskite films prepared by this method displayed uniform and densely packed grains, which exhibited a lower trap density and suppressed nonradiative charge recombination. A power conversion efficiency as high as 23.16% was achieved under optimized conditions. More importantly, the unencapsulated devices maintained more than 90% of the initial power conversion efficiency after being stored in a glovebox filled with N-2 for 3200 h, showing very good stability.