Crystal-array-assisted growth of a perovskite absorption layer for efficient and stable solar cells

The photovoltaic performance and stability of perovskite solar cells (PSCs) are closely related to the quality of the absorption layer. Further improving the crystallinity of perovskite films is of great significance for the commercial application of PSCs. Here, we introduce a perovskite crystal array (PCA) with regular distribution to assist the growth of the perovskite absorption layer. The PCA provides nuclei where the crystallization can commence without overcoming the critical Gibbs free energy for nucleation and induces a controllable bottom-up crystallization process under solvent annealing. As a result, a perovskite film with high crystallinity and reduced grain boundaries was obtained. The largest grain size was over 4 mu m and the average grain size was over 3 mu m. PSCs based on the perovskite film with the PCA achieved power conversion efficiencies of 25.1% (certified 24.3%) and 23.1% (certified 22.3%) with aperture areas of 0.0784 cm(2) and 1.0085 cm(2), respectively. The devices maintained 90% of their initial efficiency after operation at the maximum power point for 2000 hours under 1 sun illumination.