Additive Engineering: A Route Towards Flexible and Robust Perovskite Solar Cells

The record performance reached by metal halide perovskite in solar cells in a very short time calls for a real word application, however, several major intrinsic limitations need to be solved before the technological maturation can be reached. The intrinsic instability, the poor control of perovskite materials' properties deposited via wet processing, and the intrinsic mechanical fragility of the polycrystalline films are the among the most relevant issue. Herein, the use of polymeric additive has been investigated as a mean to gaining a control over the processing and improving the perovskite material stability to the environmental factors, eventually to developing perovskite inks compatible with large area solar cells manufacturing. Several polymers were evaluated based on their solubility and compatibility with perovskite precursors solutions. Among all, starch polysaccharide has been selected since it can induce a convenient viscosity modulation that make perovskite precursors' inks with different printing techniques. Importantly, starch can also enhance perovskite materials mechanical strength and tolerance to thermal stress.