Nature inspiring processing route toward high throughput production of perovskite photovoltaics

Abstract

We report our results of developing perovskite thin films with high coverage, improved uniformity and preserved crystalline continuity in a single pass deposition. This approach, inspired by the natural phenomena of tears of wine, works by regulating the hydrodynamics of the material comprising of droplets during spray-pyrolysis. In contrast to conventional spray-pyrolysis where droplets dry independently and form a rough morphology, the use of binary solvent system creates localized surface tension gradients that initiate Marangoni flows, thus directing the incoming droplets to spontaneously undergo coalescing, merging and spreading into a continuous wet films before drying. By systematically exploring the dynamics of spreading and drying, we achieve spray-coated perovskite photovoltaics with power conversion efficiency of 14.2%, a near two-fold improvement than that of the spray-pyrolysis counterpart. Of particular significance is the fact that the single pass deposition technique unveils novel inroads in efficient management of lead consumption during deposition.