Rapid thermal evaporation of Bi sub(2)S sub(3) layer for thin film photovoltaics

Bi sub(2)S sub(3) is a promising inorganic material for thin film photovoltaic application with optimum direct band gap of ~1.3 eV, strong absorption coefficient, nontoxic and simple composition. Here we introduce rapid thermal evaporation (RTE), a method with simple facility and extremely fast deposition speed, to produce high quality Bi sub(2)S sub(3) films. By optimizing the substrate temperature and post-annealing process, well-crystalline, smooth and compact Bi sub(2)S sub(3) films were obtained. The band gap, doping type and density, and photosensitivity of as-produced Bi sub(2)S sub(3) films were revealed by a combined X-ray diffraction, Scanning electron microscopy (SEM), Raman spectrum, X-ray photoelectron spectroscopy (XPS), Energy dispersive spectroscopy (EDS), Hall effect and photoresponse measurements. Finally, a prototypical ITO/NiO/Bi sub(2)S sub(3)/Au solar cell with 0.75% power conversion efficiency was obtained, manifesting the promise of Bi sub(2)S sub(3) as the absorber layer for thin film photovoltaics.