Pin-hole free MAPb0.75 Sn0.25(I0.5Br0.5)3 films spin casted without anti solvent by adding MAAc additive to Perovskite ink

Abstract

To start the crystallization of the tin (Sn) based perovskite materials, anti-solvent treatment is a useful technique. But the use of anti-solvents increases the complexity of the deposition process thus hinders the applicability in mass production processes. Here we have developed an anti-solvent free MAPb0.75Sn0.25(I0.50Br0.50)3 perovskite thin film deposition method based on a one step spin coating process. Addition of 0 - 100 mol% of methylammonium acetate (MAAc) to the precursor ink allows for the deposition of continuous films. Films casted from ink with less than 60 mol% MAAc show pinholes and are rough. A decent crystalline and pin-hole free perovskite thin film can be obtained from 60 or more mol% MAAc additive. These results are confirmed by XRD, AFM and SEM measurements. MAPb0.75Sn0.25(I0.50Br0.50)3 has a wide bandgap and is currently being considered for applications in tandem solar cells and under water solar cells.