Morphology and Defect Control of Metal Halide Perovskite Films for High-Performance Optoelectronics

Delicate morphology and defect control are crucial for high-performance optoelectronics. For metal halide perovskites, antisolvent precipitation is the most common process to realize the control and develop the state-of-art devices. However, the solute/solvent/antisolvent interactions and their influence on the film formation process are unclear. Here, we propose a novel solubility parameter δDN to measure the coordinate interaction between solvent and perovskite precursors. A combination of δDN and Hansen’s solubility parameters allows for the first comprehensive analysis of interactions between pure liquids and the perovskite precursors. The relative energy difference (RED) between antisolvent and solvent is used to quantify the supersaturation level during film deposition. Dense morphology films form in the maximum supersaturation region (0.85 < RED < 1.00). Perovskite properties are controlled by the interaction behavior difference in antisolvent/solutes. The photovoltaic performance increases by 53% when RED increases from 0.416 to 0.858. We demonstrate that detailed knowledge of the physicochemical characteristics of the solutions used to form films of perovskites is a valuable tool in the discovery of optimum film formation conditions and consequently in attaining efficient optoelectronic performance.