Defect tolerant perovskite solar cells from blade coated non-toxic solvents

Abstract

Understanding crystallization of lead halide perovskites by industrially relevant techniques using non-toxic solvents is a topic that needs development. To this date, highest efficiency devices are prepared by deposition of the perovskite layer using non-scalable techniques, toxic solvents and/or require additional processing steps. In this work, we show that efficient one-step perovskite solar cells can be obtained by doctor blade. The perovskite film is formed under supersaturation regime from non-toxic solvents following spherulitic growth. This method results in highly crystalline perovskite films with preferential crystal orientation. Co-local photoluminescence and light-beam induced current experiments show that generated chemical defects are confined at the boundary of spherulites and these do not have a negative effect on the extracted photocurrent. Strikingly, spherulitic formation, rather than being detrimental, can lead to better photovoltaic performance in hybrid perovskite films. This is further confirmed in photovoltaic devices with record efficiencies of 18.0% for MAPbI3 (MA= Methyl ammonium) for doctor bladed processing using non-toxic solvents. Moreover, large area devices (1.53 cm2) fabricated using doctor blade show remarkable efficiencies (14.2%) reinforcing the viability of this solar technology towards industrialization.