Preparation of CZTS thin films for the fabrication of ZnO nanorods based superstrate solar cells

Abstract

Intensive studies have recently been performed to produce low-cost, environmentally friendly and high-efficiency cells. Some of these studies are associated with the incorporation of one-dimensional nanostructures into thin film based solar cell architecture. The aim of this work was therefore to build one of these structures by incorporating ZnO nanorod into the conventional Cu2ZnSnS4 (CZTS) thin film system. To achieve this, conformally CdS-coated vertically-aligned ZnO nanorods (NRs) were first successfully synthesized on ITO-coated substrates by using the hydrothermal technique. ZnO NRs were then decorated with 600 nm thick CZTS thin layer by a one-step thermal evaporation route to produce a SLG/ITO/ZnO-NR/CdS/CZTS/Ag superstrate solar cell architecture. The findings revealed the formation of Cu-poor mono-phase kesterite CZTS thin film with an optical band gap of 1.45 eV. The performance of the fabricated solar cell was measured both in the dark and under irradiation of (AM) 1.5 G at room temperature. The superstrate solar cell had a short-circuit current density of ~20.80 mA/cm2, an open-circuit voltage of ~0.46 V, a fill factor of ~29.5%, providing ~2.82% of the energy conversion efficiency.