Fabrication of thin film for triple-cation perovskite via hot-bar-coating method without post-annealing process

The triple-cation perovskite Cs_0.05(MA_0.17FA_0.83)_0.95Pb(I_0.83Br_0.17)₃ was deposited using the hot-bar-coating method. The effects of the substrate temperature and coating bar sweep speed on the film quality were investigated. Coating the precursor solution at a substrate temperature of 150 °C, reduced fabrication time by eliminating the post-annealing process, which is essential to conventional film fabrication methods, i.e., the antisolvent method. We further investigated the dependence of thin film thickness and quality on the coating bar sweep speed, finding that the optimal film quality was achieved at a speed of 4 mm/s. Importantly, decomposition into PbI₂ was not observed during film fabrication for the triple-cation perovskite. The results of solar cell property measurements, indicating that the fabricated devices maintained high performance for 500 h in ambient air, suggest that the hot-bar-coating method is a promising approach for producing perovskite solar cells with high atmospheric stability and potentially low cost.