Variation of sulfur concentration on the effective deposition of solution processed ZnS thin films for buffer layer in thin film solar cells

Abstract

The influence of sulfur concentrations on the growth of ZnS thin films were investigated by low cost chemical spray pyrolysis and chemical bath deposition techniques. The deposited ZnS films showed the major peaks at (111) zinc blende structure from X-ray-diffraction. The FESEM analysis resulted that the deposited films were identified as sphere-like particles for both deposition techniques and the ZnS particle size improved as the sulfur concentration increased in the prepared solutions. The UV analysis showed higher optical transmittance > 70% in the visible region and PL spectra exhibited the defects-free ZnS peaks at blue-green emission bands in the range between 350 nm and 550 nm by both deposition methods. The linear response of I-V characteristics denote to ohmic behavior of the deposited films and the calculated resistivity of the films were in the range of 107Ω.cm and 108 Ω.cm. Hence, the characterized results suggest that the deposited ZnS films with increasing sulfur concentration using both deposition methods show optimum properties for buffer layers in thin film photovoltaics.