Synthesis of the Sn-based CaSnS3 chalcogenide perovskite thin film as a highly stable photoabsorber for optoelectronic applications

Abstract

We report the synthesis and characterization of the stannous based CaSnS3 chalcogenide perovskite thin film prepared through simple chemical route, and providing a detailed experimental and theoretical investigation of such material. Several attempts were performed to reach optimal conditions, starting from the oxide thin film deposition to the sulfurization process. The crystal identification using X-ray diffraction (XRD) and Raman analysis indicated the formation of a polycrystalline film with no secondary phases detected within the detection limits of the characterization methods employed. Field emission scanning electron microscopy (FE-SEM) screening displayed a notable enhancement on the resulted surfaces, while energy dispersive X-ray spectrometer (EDX) mapping showed the drastic change in the sulfur content with good distribution and homogeneity of the elements on the obtained surfaces. Optical measurements indicated a direct band gap of 1,72 eV in good agreement with our theoretical calculation using the generalized gradient approximation of the modified Becke-Johnson (GGA-mBJ), alongside with an absorption coefficient in the order of 105 cm−1. The Hall effect measurements revealed a p-type conductivity and a carrier concentration of 1.216.1017 cm−3 with an outstanding carrier mobility recorded at 1.314.102 cm2V−1s−1. The photoresponse test was conducted by collecting the Current-Voltage (I-V) variation in dark and under illumination, demonstrating a strong photoabsorption with high stability in ambient atmosphere. The results set the foundations to further investigate the stannous based chalcogenide perovskites as a promising materials for optoelectronic applications.