Research on solvent chemistry, particularly for halide perovskite intermediates, has been advancing the development of perovskite solar cells (PSCs) toward commercial applications. A predictive understanding of solvent effects on the perovskite formation is thus essential. This work systematically discloses the relationship among the basicity of solvents, solvent-contained intermediate structures, and intermediate-to-perovskite α-FAPbI₃ evolutions. Depending on their basicity, solvents exhibit their own favorite bonding selection with FA⁺ or Pb²⁺ cations by forming either hydrogen bonds or coordination bonds, resulting in two different kinds of intermediate structures. While both intermediates can be evolved into α-FAPbI₃ below the δ-to-α thermodynamic temperature, the hydrogen-bond-favorable kind could form defect-less α-FAPbI₃ via sidestepping the break of strong coordination bonds. The disclosed solvent gaming mechanism guides the solvent selection for fabricating high-quality perovskite films and thus high-performance PSCs and modules.

Crown ether effectively stabilizes the cubic phase of CsPbI₃ to inhibit the moisture invasion and phase transformation of CsPbI₃ films, producing large-area devices and improving device performance.

Through optimization of the thickness of the m-TiO ₂ layer, rather stable perovskite solar cells which maintain over 85% of the initial power conversion efficiency (PCE) even after storage for 100 days in air were accomplished.

Vapor-assisted deposition of organometal trihalide perovskite films shows particular advantages in high-quality film preparation and mass-production because of the precisely controlled vapor–solid reaction. However, a high-vacuum environment is required for the deposition process, which is not suitable for the production of low-cost next-generation solar cells. Here, a modified vapor-assisted deposition method for high-quality perovskite films fully under the ambient atmosphere has been developed that exhibits superior ambient tolerance, even at high relative humidity of over 60%. The crystallization behaviors of the perovskite films were investigated in detail, and were highly dependent on the vapor diffusion and reaction at the interface and film recrystallization induced by the proposed in situ annealing process. The uniform, high-quality perovskite films produced efficient perovskite photovoltaics with power conversion efficiency of over 18% (highest value of 18.90%).