Vapor-assisted solution process for perovskite materials and solar cells

Hybrid organic-inorganic perovskites (e.g., CH₃NH₃PbX₃, X represents a halide) have been highlighted for various applications, especially as light absorbers in third-generation photovoltaics. In the pursuit of low-cost and efficient perovskite solar technology, it is crucial to develop a facile method to fabricate conformal, compact perovskite films in an inexpensive and reproducible manner. Here, we report high-quality perovskite films controllably deposited via a facile lowerature (<150°C) vapor-assisted solution process (VASP). Key steps include deposition of the inorganic framework by solution first, followed by a subsequent in situ reaction between the inorganic species and the desired organic vapor. The VASP approach differs from other conventional solution processing techniques because it retards nucleation and enables vigorous reorganization for film growth, with an absence of solvation, hydration, and undesirable structural transitions. Facilitated by excellent film quality, perovskite materials enable a power-conversion efficiency of ∼16.8% in the planar configuration of a solar cell. This method provides a simple approach to perovskite film preparation and paves the way toward high reproducibility and mass production of high-quality absorber films for solar devices.