Nucleation mediated interfacial precipitation for architectural perovskite films with enhanced photovoltaic performance.

Perovskite films are a promising candidate for future highly efficient and low-cost solar cells. The long diffusion length of charge carriers in the perovskite film makes its architecture fabrication seem unnecessary, while the rapid crystallization process increases the difficulty in its architecture fabrication. Here we show the fabrication of perovskite architectures through a nucleation mediated interfacial precipitation method with the proper immiscible anti-solvent. Consecutively evolved architectures from tri-layer porous films to bilayer dense films are obtained. The interfacial precipitation provides the possibility of controlling the crystallization process of perovskite films, while the secondary nucleation is the origin of the porous architecture. The nucleation mediation can be a novel bottom-up approach to fabricate architectural perovskite films. The tri-layer architectural perovskite film exhibits excellent light absorption in the range of 500-800 nm and good photovoltaic performance with 8.2% enhancement in efficiency compared with the bilayer film for the corresponding solar cells.