Investigating Ag2S quantum dot buffer layer in CZTSSe photovoltaics for enhanced performance

Abstract

Abstract This study focuses on optimizing the performance of CZTSSe (Copper Zinc Tin Sulphide/Selenide) photovoltaic (PV) cells by incorporating an Ag2S quantum dot (QD) buffer layer. CZTSSe, with its significant Direct bandgap (1–1.5 eV) and the absorption coefficient (>104 cm−1), shows promise for efficient visible-range light absorption. Ag2S quantum dots, known in terms of their favourable attributes, such as high absorption, low solubility, and minimal surface recombination, are explored as a buffer layer material. The effects of the Ag2S quantum dot (QD) buffer layer on the optical and electrical characteristics of CZTSSe photovoltaic (PV) cells are comprehensively examined using simulation characterization. Key parameters, including Short-circuit (JSC), fill factor (FF), open-circuit voltage (VOC), and power conversion efficiency (PCE), are analyzed to validate device characteristics. The SCAPS-1d simulator is employed for performance assessment and enhancement through tuning device parameters such as energy bandgap, absorber layer thickness, buffer layer thickness, defect density, and acceptor concentrations of the absorber and hole transport layer (HTL), and donor concentrations of the buffer. Additionally, temperatures, as well as series-shunt resistance’s influence on device effectiveness, are explored. The study aims to maximize light absorption, enhance charge conduction, reduce carrier loss due to recombination, and upgrade CZTSSe PV cells’ overall performance. The CZTSSe solar unit achieves its highest PCE of 27.56% when employing an Ag2S buffer layer and Cu2O hole transport layer. The study provides valuable knowledge about the optimization of CZTSSe solar cells and the potential benefits of utilizing Ag2S QD in the role of buffer layer material. This research contributes to the understanding of enhancing CZTSSe PV cell performance through the incorporation of Ag2S QD buffer layers and presents pragmatic directives that can be employed to facilitate the progression of CZTSSe-based photovoltaic devices.