Optoelectronic evaluation of SrMnO3 cubic perovskite for prospective visible light solar photovoltaic application

Abstract

Next-generation solar cell materials with superior optoelectronic and photovoltaic properties must circumvent the toxicity and degradation issues of hybrid lead halide perovskites. In this regard, transition metal oxide perovskites with favourable optoelectronic properties are of significant relevance. In this work, we report a combined theoretical-experimental investigation into the optoelectronic properties of cubic-perovskite, SrMnO3 (SMO) for prospective visible-light photovoltaic application. Using first-principles density functional theory calculations, we show that SMO with cubic symmetry demonstrates a direct bandgap character (similar to 0.62 eV), exceptional absorption behaviour (similar to 10(5) cm(-1) in the visible range), substantial dielectric constant (similar to 11) and a reasonably small exciton binding energy (similar to 44 meV) promising a sizeable photovoltaic response (PCESLME similar to 16 %). Accordingly, thin films of SMO were grown on fluorine-doped tin oxide (FTO) coated glass substrate using pulsed laser deposition (PLD) technique. Structural characterization demonstrated phase pure SMO with cubic symmetry. Room-temperature Hall measurement allowed the determination of the nature (p-type) and concentration (1.37 x 10(12) cm(-3)) of majority charge carriers, conductivity (5.56 x 10(-6) S/cm), and carrier mobility (24.5 cm(2)/V center dot s) which are reasonably comparable to those of archetypal halide perovskite, CH3NH3PbI3 (MAPbI(3)). Ultraviolet photoelectron spectroscopy further allowed the determination of energies corresponding to valence and conduction band edges, crucial for device fabrication. Initial device characterization demonstrates small yet finite photovoltaic response, suggesting the requirement of thorough optimization of the device fabrication parameters and development of a suitable hole transport layer.