Perovskite MAPbI3 preparation by using deep eutectic solvents (DES) based on acetamide

Abstract

In this work, we replaced the conventional solvents such as dimethyl sulfoxide (DMSO) or dimethylformamide (DMF) by deep eutectic solvents (DES) in the synthesis of methylammonium lead iodide perovskite (MAPbI3). The first DES system was based on the combination of acetamide and urea (A–U–P system), the homogenous solution was formed at relative low temperature (~40°C). For the second system which was based on acetamide and choline chloride (A–C–P system), lead nitrate only dissolved at higher temperature (~100°C). Interestingly, lead nitrate did not precipitate when cooling down the solutions to room temperature for both systems, instead they existed as homogenous gel–like mixtures. From these lead precursors, the MAPbI3 have been formed successfully on the glass substrates by two-step synthesis method. X-rays diffraction showed that MAPbI3 existed in three different phases such as Tetragonal, Cubic and Orthorhombic. Scanning electron microscope (SEM) results indicated that the perovskite films formed from both systems possessed high quality with large grain size, few grain boundaries and few pin–holes. The results expressed the possibility in using DES for preparing perovskite MAPbI3 thin films which are ready for applications such as solar cells, resistive random-access memory.