Tunable thiocyanate-doped perovskite microstructure via water-ethanol additives for stable solar cells at ambient conditions

Abstract

Organic-inorganic halide perovskite materials have emerged as highly efficient solar absorbers produced under low-cost processing conditions. However, due to the hygroscopic nature of halide perovskite materials, moisture significantly affects the stability, lifetime and performance of the device. In this work, we combine thiocyanate-doped pseudohalide perovskite with additive solvents to achieve compact films showing high-quality crystal grains with improved longevity of the perovskite films using a simple two-step spin-coating method under ambient conditions. Indeed, we confirm that humidity has a profound impact on the crystal quality. Perovskite films with grain sizes as large as 4 μm are produced in high humidity conditions, using methylammonium iodide precursor solution mixed with deionized water and ethanol. Power conversion efficiencies up-to 9.4% have been achieved for optimized planar device architectures fabricated above 60% relative humidity. Scanning electron microscopy, X-ray diffraction and current-voltage characteristics for devices stored in ambient conditions for more than 480 h show that the films are quite stable with only a 12% decay of their initial power conversion efficiency.