All electrospray printed perovskite solar cells

The power conversion efficiencies of perovskite solar cells (PSCs) have reached 23.3% recently, rivaling those of established photovoltaic technologies. For PSCs to be commercially competitive, one of the important challenges is to overcome the limitations of small area and excessive material waste from spin-coating. Electrospray printing is a scalable and roll-to-roll compatible method with high material utilization rate. Here, we report an all electrospray printing process for PSCs in ambient air below 150 degrees C. Strategies for successful electrospray printing of PSCs include formulating the precursor inks with solvents of low vapor pressures and judicial choice of droplet flight time, as well as tailoring the wetting property of the substrate to suppress coffee ring effects. Implementation of these strategies leads to pin-hole free, smooth and uniform perovskite layer, hole transport layer and electron transport layer. The power conversion efficiency of the all electrospray printed devices reaches up to 15.0%, which is the highest to date for fully printed PSCs using mainstream printing methods in air without significant material waste.