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.