Improving the Photovoltaic Characteristics for n-CdS/p-Cu 2 ZnSnS 4 Solar Cells by annealing: Structural, Morphological and Optical Properties

Abstract Owing to its direct bandgap in the range to be used as an absorbent material and due to its high absorption rate, kesterite Cu2ZnSnS4 (CZTS) is a p-type prospective absorber material for solar cell applications. Kesterite Cu2ZnSnS4 (CZTS) thin films were prepared using the thermal evaporation technique. Thermogravimetric analysis (TGA) was first performed for the (CZTS) nanoparticles. The (CZTS) thin films were annealed at different annealing temperatures chosen according to TGA analysis in the range of (400oC, 450oC, 475oC, and 500oC). The influence of annealing temperatures on the structural, morphology and optical properties of the CZTS was studied. The XRD patterns and Raman spectra have exposed the creation of CZTS thin with a high-quality crystal structure. The refractive index n, and extinction coefficient, k therefore energy gap are assessed from mathematical model of spectroscopic ellipsometry. The n and k values of the CZTS /glass films established from SE model rise with increasing the annealing temperature owing to the growth of the crystallites size. It is observed that the direct optical transition with energy gap is compressed from 1.73 eV at RT to 1.51 eV at maximum crystallization 500 oC. The photovoltaic traits of the fabricated n-CdS/p-CZTS junction were investigated for a solar cell. The heterojunction of Ni/n-CdSe/p-CdTe/Pt has been well constructed. The dark and illumination (current-voltage) traits of assembled heterojunctions had been recommended at distinctive different annealing of CZTS layer and the voltages ranging from − 2 to 2 volts.