Effect on the morphology and optical properties of CH 3 NH 3 PbI 3 with additive of NH 4 Cl

Abstract Rapid emergence of solar cells based on mixed organic-inorganic halide perovskite have led to high power conversion efficiencies of over 20% in recent years. Looking for a simple and convenient way to fine-control of the perovskite film morphology is becoming one of the main issues. In this work, we explore the effect of adding NH 4 Cl on crystallization process and optical properties of perovskite. With adding NH 4 Cl, the perovskite films prepared by one-step method present better morphology than films without adding NH 4 Cl, namely, smoother surface and better coverage which result in uniform and much more stable photoluminescence intensities as well as longer lifetime of photoexcitations. More importantly, the photovoltaic cells fabricated with the addition of the NH 4 Cl have far better performance than the cells without additives. Therefore, one-step fabrication method can also control the morphology of perovskite films finely for both optical application and solar cells with adding proper additive.