Optoelectronic and Photovoltaic Properties of the Cu2ZnSnS4 Photocathode by a Temperature-Dependent Facile Hydrothermal Route

In the present work, a one-step hydrothermal route was performed to develop the Cu2ZnSnS4 (CZTS) photoelectrode onto a conducting substrate. The photovoltaic performance of the homojunction CZTS photocathode was analyzed with a two-electrode cell system of FTO/CZTS/(0.3 M Eu3+–Eu2+)aq/graphite. An increase in reaction temperature shows a decrease in the band gap energy from 1.54 to 1.44 eV. The evolution of the kesterite CZTS structure with uniform and dense nanospheres was confirmed by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) studies. High resolution transmission electron microscopy (HR-TEM) and selected area electron diffraction (SAED) evaluations confirm the formation of polycrystalline thin films. The photoelectrochemical solar cell properties of CZTS (C1–C3) thin films demonstrate an increase in photoconversion efficiency (η) from 2.55 to 4.87% as a function of reaction temperature. The improvement in electrical conductivity and generation of lower R ct and R s of (C1–C3) thin films were confirmed using electrochemical impedance spectroscopy.