Crack-free perovskite layers for high performance and reproducible devices via improved control of ambient conditions during fabrication

Highlights - Cracking film can be avoided in summer by regulating ambient temperature. - High-quality perovskite films without cracking was prepared with low defects. - The PCE was boosted from 13.51% to 18.46% at ambient temperature of 18 °C. - High-efficiency PSCs device can be prepared at high ambient temperature. - This method can boost the efficiency of PSCs in the case of film cracking. Abstract Organic-inorganic perovskite has shown one of the most rapid growths ever in photovoltaic history and achieved remarkable achievement with PCE of 22.1%. Since the first perovskite solar cells (PSCs) was reported in 2009, it always existed a problem that the performance of PSCs prepared in winter is much better than summer due to films cracking. In this article, we explored the reasons for this phenomenon and provided a corresponding solution. It was found that film cracking was a major contributor for losses of PSCs performance. By adjusting ambient temperature of operating environment, the film quality and device performance can be increased effectively. Result showed that mirror-like perovskite film surface without cracks can be prepared by control operating environment, and the power conversion efficiency was boosted from 13% to values more than 18% measured under standard solar conditions (AM 1.5G, 100 mW/cm2). Furthermore, this method exhibits good reproducibility. It is expected that by this effective approach and better understanding of the perovskite preparation process, high efficiency and reproducible PSCs device can be prepared.