Tuning the wettability of the blade enhances solution-sheared perovskite solar cell performance

Solution-shearing is a promising technique to generate a perovskite thin film over a large area in a scalable manner, which is an important factor for the commercialization of perovskite solar cells. Thus far, solution-shearing parameters that were utilized to tune the thin-film properties have mainly been restricted to substrate temperature and coating speed. In this work, it is demonstrated that the wettability of the coating blade strongly influences the thin film properties, through which improved power conversion efficiency (PCE) was resulted. Specifically, with all other parameters fixed, rendering the blade de-wetting generates thicker films with larger crystallite size. This was correlated to the increase in light harvesting efficiency and carrier lifetime. The degree of texturing, on the other hand, was independent of the wettability of the blade; rather, it was the highest at a specific coating speed. At this coating speed using a de-wetting blade, the best PCE of 19.47% was achieved.