Synthesis and characterization of Cu-sandwiched Sb2Se3 thin films and numerical simulation of p-Sb2Se3/n-ZnSe heterojunction solar cell

Abstract

Sb2Se3 and Cu-sandwiched Sb2Se3 thin films were prepared by sequential evaporation of (Sb/Se) × 3 and [(Cu/(Sb/Se) × 3/Cu)] precursor stacks over the glass substrates in a high vacuum using electron beam (e-beam) evaporation followed by annealing in a tubular furnace at various temperatures in Ar atmosphere. The growth of Sb2Se3 and Cu-sandwiched Sb2Se3 films is studied by varying annealing temperature. The Sb2Se3 films grown without copper layers were peeled off from the glass substrates when annealed above 300 °C, whereas the Cu-sandwiched Sb2Se3 films were adherent to substrates up to 450 °C. The XRD of Cu-sandwiched Sb2Se3 films annealed at all temperatures confirms the Sb2Se3 formation with orthorhombic crystal structure. The Cu-sandwiched films annealed at ≤ 250 °C showed the preferred orientation along the (hk0) plane, whereas films annealed at ≥ 300 °C exhibited the (hk1) preferred orientation. The morphology of Cu-sandwiched Sb2Se3 films annealed at 450 °C showed compact and larger grains (∼0.8 μm) with a direct optical band gap of 1.04 eV. Hall effect measurement exhibited a p-type conductivity with a hole concentration of 3.1 × 1015 cm−3. The numerical simulation of the proposed Glass/Ni/p-Sb2Se3/n-ZnSe/ITO/Al heterojunction solar cell showed a power conversion efficiency of 21.51%.