BaBiO₃: A potential absorber for all-oxide photovoltaics

Abstract

BaBiO₃ is presented as a potential absorber for all-oxide solar cells. Thin-films of BaBiO₃ were deposited by pulsed laser deposition. As-deposited thin-films were amorphous, but a rapid thermal anneal at 600 °C for 10 min yields polycrystalline thin-films. X-ray photoelectron spectroscopy measurements show that deposited films have Barium in Ba⁺² state and bismuth in both Bi⁺³ and Bi⁺⁵ state. UV–Vis spectrophotometer (UV–Vis) shows that BaBiO₃ films have direct and indirect bandgap (Eg) of 2.25 eV and 2.02 eV respectively, while ultraviolet photoelectron spectroscopy (UPS) shows that valence band maxima (EV), conduction band minima (EC) and work-function (ϕ) of BaBiO₃ is at 5.82 eV, 3.8 eV and 4.22 eV respectively. BaBiO₃ thin-film devices with a FTO/c-TiO₂/BaBiO₃/Au structure show rectifying current–voltage characteristics in dark. Under illumination, a photo response with a Jlight/Jdark ratio of 1.75 is observed.