Open PRAIRIE: Open Public Research Access Institutional Repository and Information Exchange
Abstract
CH3NH3SnI3 and CH3NH3PbI3 have become very promising light absorbing materials for photovoltaic devices over the last several years. CH3NH3PbI3 based perovskite solar cells have reached a solar-to-electricity conversion efficiency of ~ 22%. Nevertheless, CH3NH3PbI3 perovskite solar cells contain lead, which has serious consequences for the environment and human health. In this work, the lead was replaced with less toxic tin. Lead free CH3NH3SnI3 perovskite thin film was prepared by two low temperature solution processing methods and characterized using various tools such as Xray Diffraction (XRD) and absorption spectroscopy (UV-VIS). The distinctive p-type semiconducting nature and metal like conductivity of CH3NH3SnI3 were confirmed by the measurements of electrical and optical properties. Crystal structures and uniform film formation of CH3NH3SnI3 layer were analyzed by XRD and scanning electron microscopy (SEM). The CH3NH3SnI3 film morphology, uniformity, light absorption and electrical properties strongly depend on the preparation methods and precursor solutions. The CH3NH3SnI3 perovskites fabricated using dimethylformamide (DMF) exhibited higher crystallinity and stronger light harvesting capability than those fabricated using a blend solvent of dimethyl sulfoxide (DMSO) and gamma-butyrolactone (GBL). The local nanoscale photocurrent mapping confirmed that CH3NH3SnI3 can be used as an active layer and has a potential to fabricate lead free photovoltaic devices. The CH3NH3SnI3 film also showed a strong absorption in visible and near infrared spectrum with an absorption onset of 1.3 eV
