Highly (100)-oriented CH₃NH₃PbI₃(Cl) perovskite solar cells prepared with NH₄Cl using an air blow method

The effects of adding NH₄Cl via an air blow process on CH₃NH₃PbI₃(Cl) perovskite solar cells were investigated. CH₃NH₃PbI₃(Cl) solar cells containing various amounts of NH₄Cl were fabricated by spin-coating. The microstructures of the resulting cells were investigated by X-ray diffraction, optical microscopy, and scanning electron microscopy. The current density-voltage characteristics of the cell were improved by adding an appropriate amount of NH₄Cl and air blowing, which increased the photoconversion efficiency to 14%. Microstructure analysis indicated that the perovskite layer contained dense grains with strong (100) orientation, as a result of NH₄Cl addition and air blowing. The ratio of the (100)/(210) reflection intensities for the perovskite crystals was 2000 times higher than that of randomly oriented grains. The devices were stable when stored in ambient air for two weeks.