Solvent and Spinning Speed Effects on CH3NH3PbI3 Films Deposited by Spin Coating

Abstract

Herein, methylammonium lead triode (CH3NH3PbI3) perovskite thin films are prepared by the one‐step deposition spin‐coating process on glass substrates. The effects of solvent nature and speed centrifugation on films' morphology and structure are investigated. Two solvents are used: N,N‐dimethyl formamide (DMF) and a mixture of dimethyl sulfoxide (DMSO) with DMF. The spinning speed varies in the range 700–2000 rpm. Scanning electron microscopy (SEM) observations reveal that the prepared films are not continuous with variable morphologies; the films are formed with elongated fibers. X‐ray diffraction (XRD) analysis confirms the tetragonal structure of the prepared perovskite. The film structure is also investigated by Raman spectroscopy. The film's optical properties are studied using UV spectroscopy. The results indicate that solvent nature and spinning velocity alter film morphology. With increasing spinning velocity, the films' porosity increases. The films' formation is controlled by the competition between the radial force due to spinning velocity and resistive force due to solution viscosity.