Highly (100)-oriented CH₃NH₃PbI₃ thin film fabricated by bar-coating method and its additive effect of ammonium chloride

CH₃NH₃PbI₃ (MAPbI₃) thin films were fabricated via a bar-coating process, which is appropriate for large-scale and mass production. By using the bar-coating process, the plane orientation [100] of MAPbI₃ was vertically aligned in the thin film on the substrate. Blending NH₄Cl to the precursor solution before the bar-coating, the film quality markedly changed depending on the amount of NH₄Cl, resulting in the suppression of the grain boundary and the improvement of the surface morphology. Thus, the highly (100)-oriented and uniform thin film of MAPbI₃ with the large grains could be obtained. Typical inverted-type solar cells were fabricated using such an excellent MAPbI₃ thin film, and the high device performance was demonstrated.