Green solvent strategies for the sustainable development of perovskite solar cells

Perovskite solar cells have been of great interest over the past decade, reaching a remarkable power conversion efficiency of 26.7%, which is comparable to best performing silicon devices. Moreover, the capability of perovskite solar cells to be solution-processed at low cost makes them an ideal candidate for future photovoltaic systems that could replace expensive silicon and III-V systems. However, the current state of solution-processing of perovskite solar cells is heavily dependent on toxic solvents such as DMF, chlorobenzene, diethyl ether and so on. As perovskite devices approach commercialization and large-scale fabrication, a solution must first be found to reduce the toxic risks associated with the processes. This review article presents a summary of general attempts at achieving fully green-processed perovskite solar cell fabrication. A thorough examination of popular solvents and possible alternatives is first performed, followed by their applications in perovskite layer fabrication (including solvents and anti-solvents) and charge transport layer fabrication processes.