(The) effect of process conditions on the formation of $CH_3NH_3PbI_3$ perovskite absorber layer and on final device performance

Abstract

Inorganic-organic hybrid lead halide perovskite solar cells have recently become the center of photovoltaic research due to their remarkable progress in the past few years. With efficiencies now over 20 %, many researchers have begun to believe that perovskite solar cells may be able to challenge the silicon solar cell industry as perovskite solar cells offer promising prospects on both producing higher efficiencies and on having significantly lower manufacturing costs. However, fundamental understanding of the physics involved in perovskite solar cells is still very much in its early stages when compared to its efficiency. Studies on the physical reasoning behind different process conditions have been insufficient. This report studies the effect of process conditions on the formation of $CH_3NH_3PbI_3$ perovskite absorber layer and, consequently, on final device performance. Analysis using KPFM and c-AFM provided fundamental evidence to suggest that the annealing of the $PbI_2$ layer plays a critical role in effective charge separation and thus superior device performance. An attempt was made to change the absorber morphology from cuboid to thin film. However, preliminary results showed that changing the perovskite morphology resulted in decreasing efficiency to some extent. Further research is required to optimize these layers