Energy and Materials Research

Biography

Biography: Rahim Munir

Abstract

Organic-inorganic hybrid lead halide perovskite semiconductors have attracted a great deal of attention because of their remarkable optoelectronic properties which make them potentially suitable as active materials in photovoltaics, light emission, and photodetection. The key reason for its popularity is that it can yield good semiconductor properties despite being solution processed in ambient conditions and requires no vacuum or excessive heating. To date, the most efficient perovskite solar cells have been fabricated using spin coating, for which several ink and solvent engineering methods have been developed and perfected. However, this is a wasteful process which cannot be easily scaled up to continuous large area fabrication, where existing solvent engineering methods, such as anti-solvent dripping, are also unlikely to work. Here we compare the ink solidification and film formation mechanisms of CH₃NH₃PbI₃ in DMF by spin-coating versus blade-coating using in-situ time-resolved optical metrology and x-ray scattering. We show signifi cant differences in the process kinetics and formation of complex intermediate phases between the two processes at room and intermediate temperatures. To overcome these challenges in the context of blade coating, the sample is heated during deposition. We observe high-quality film formation for T > 100^oC, namely in conditions which inhibit the formation of the crystalline intermediate complex phases. In doing so, we achieve fast and direct formation of the perovskite phase with solar cells yielding PCE > 17%.