Optical and morphological properties of Ge-incorporated polycrystalline Sb2Se3 thin-film for photovoltaic applications

Crystalline Ge-incorporated Sb2Se3 thin-films are the promising absorber material for third-generation solar cells due to its optical, electrical, and material properties with earth-abundant materials. In this contribution, we have grown polycrystalline Ge-incorporated Sb2Se3 thin-film absorbers and conducted morphological and optical analysis by Scanning Electron Microscopy and UV-Vis spectroscopy along with the chemical structure analysis with Raman Spectroscopy for photovoltaic absorber applications. Ge-incorporated Sb2Se3 thin-films were deposited with Vapor Transport Deposition techniques, using thermally evaporated Sb2Se3 and Ge from each Sb2Se3 and Ge nanopowder source as precursors. Evaporation temperatures of Sb2Se3 and Ge nanopowder sources were independently controlled in the different heating zones of the furnace. At the deposition temper-ature of 300 degrees C, grains of Ge-incorporated Sb2Se3 thin-film begin to grow due to the increased crystallization temperature by Ge incorporation. With temperature-dependent absorption spectrum and the indirect optical transition natures, the optical bandgap of Ge-incorporated Sb2Se3 absorbers is extracted as 1.15 eV and 1.23 eV for samples grown at 500 degrees C and 520 degrees C.