Effects of temperature and coating speed on the morphology of solution-sheared halide perovskite thin-films

In this work, we have conducted a systematic study of the crystallization of perovskite thin-films during solution-shearing to elucidate how parameters such as substrate temperature and coating speed influence the morphology of the thin-film. Four distinct phases are identified and a morphological phase map is constructed. The formation of these phases is attributed to a delicate balance between the degree and rate of supersaturation and the flux of solution supply to the meniscus line, which dictates the nucleation and the crystal growth process. An optimal phase window is identified and the photovoltaic device under the chosen conditions exhibits a power conversion efficiency over 15%, which is comparable to that of a reference device prepared by the conventional spin-coating process. Furthermore, a large area perovskite film of 57 cm(2) is prepared. Small-area devices from different locations within the large-area film show uniform efficiencies with a deviation coefficient of 4.2%, demonstrating the high uniformity of the thin-film.