The optical properties of strontium manganite thin films prepared by novel phototreatment technique

Abstract

SrMnO3 thin films were successfully prepared by spin coating the viscous solution obtained from the autocombustion synthesis. To ensure the transformation of the precursor solution into the manganite phase, conventional thermal treatment and novel phototreatment were applied. The thermal treatment resulted in stable hexagonal SrMnO3, while phototreatment yielded cubic SrMnO3 phase which is usually not stable at ambient conditions. The optical properties of the prepared materials were measured revealing the optical gaps of 1.5 eV for thermally treated material and about 1.3 – 1.4 eV for the phototreated samples. Comparison with ab initio result shows a higher theoretical value of 1.9 eV, ascribed to high exciton binding energy. Since these values are similar to the optical gap (1.48 eV) of widely studied formamidium lead iodide thin films, SrMnO3 thin films are promising candidates for active layers in inorganic perovskite solar cells.