Surfactant-controlled ink drying enables high-speed deposition of perovskite films for efficient photovoltaic modules

Abstract

Novel photovoltaic technologies such as perovskites hold the promise of a reduced levelized cost of electricity, but the low-cost potential depends on the ability to scale-up solution-based deposition. So far, complex fluid dynamics have limited the solution deposition of uniform pinhole-free organic–inorganic perovskite thin films over large areas. Here, we show that very small amounts (tens of parts per million) of surfactants (for example, l-α-Phosphatidylcholine) dramatically alter the fluid drying dynamics and increase the adhesion of the perovskite ink to the underlying non-wetting charge transport layer. The additives enable blading of smooth perovskite films at a coating rate of 180 m h–1 with root-mean-square roughness of 14.5 nm over 1 cm. The surfactants also passivate charge traps, resulting in efficiencies over 20% for small-area solar cells. Fast blading in air of perovskite films results in stabilized module efficiencies of 15.3% and 14.6% measured at aperture areas of 33.0 cm2 and 57.2 cm2, respectively. Scaling up perovskite film deposition necessitates controlling the film formation dynamics. Here, Deng et al. use amphoteric choline surfactants to blade-coat well-passivated films, reaching module efficiencies of ~15% for aperture areas up to 57 cm2.