Electrohydrodynamically Assisted Deposition of Efficient Perovskite Photovoltaics

Organic-inorganic perovskites that combine the strength of both chemical worlds have emerged as tantalizing candidates for next generation photovoltaics. Here, the electrohydrodynamically assisted continuous liquid interface propagation as a general, and potentially scalable nanomanufacturing route toward synthesizing high quality perovskite thin films in a rapid and high throughput fashion is reported. This strategy conceptually mimics the advantageous self-organizing features of emulsion droplets where the use of a binary solvent system, concurrently and continuously, initiates a three-stage process of coalescence, spreading, and merging, thus optimizing thin film morphology upon deposition without the needs for additional engineering steps. The resulting perovskite thin film not only exhibits a smooth topology with the root mean square roughness of only a few nm but also reveals hybrid morphology where micrometer-sized grains intersperse between interconnected and continuous crystalline networks. This gives rise to the highest power conversion efficiency of 16.50% and average 14.68%; representing a nearly twofold increase compared to that of conventional spray-pyrolysis approach. As a final critical aspect, the proposed strategy contributes new insights to efficiently managing the environmentally hazardous lead during processing, significantly reducing the amount by two orders of magnitude compared to that of spin-coating to achieve the same thin film thickness.