Influence of Deposition Parameters on Performance of Zn(O,S) Buffer Layer Deposited by Solution-Based Continuous Flow Reactor for CIGS Solar Cells

Abstract

CdS thin films are commonly used as buffer layers in hetero-junction structured CIGS thin film solar cells. However, the toxicity of Cd has raised concerns regarding environmental safety and alternative materials have been explored. ZnS is a leading candidate to replace Cd, with the presence of Zn(O,S) impurities known to be required for efficient CIGS solar cell fabrication. In this study, we synthesized Zn(O,S) films using a solution-based deposition method combining a continuous flow reactor (CFR) with another solutionbased deposition method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the structural and physicochemical properties of the films, confirming the efficacy of the CFR process for depositing Zn(O,S) thin films in a short period of time. We successfully deposited Zn(O,S) thin films using the combined CFR process. Cd-free B:ZnO/Zn(O,S)/CIGS solar cells were fabricated on Mo-coated glass substrates to investigate the effects of experimental parameters, such as deposition time and method, on the performance of the Zn(O,S) buffer layer in the devices.