Studies on copper indium selenide/Zinc sulphide semiconductor quantum dots for solar cell applications

Abstract

Despite dedicated efforts to develop efficient quantum dot sensitized (QDS) photovoltaic cells, the efficiency of these cells still lags behind their theoretical value. In order to increase photo conversion efficiency, the extant methods are predominantly focus on modifying the band gaps of quantum dots and optimizing the interfaces of cell components to increase light utilization capacity. In this study, we have designed and investigated QDS solar cells using Copper Indium Selenide (CuInSe2 or simply CIS) as a quantum dot absorber. In order to achieve tunable bandgap, increased photoluminescence, reduced density of surface defect state and higher light-harvesting efficiency, the CuInSe2 is alloying with Zinc sulfide (ZnS) to design Copper Indium Selenide-Zinc sulfide (CISZS) quantum dots. The resulting CISZS sensitizer exhibits improved photoelectric characteristics and greater chemical stability. The performance of the CIS and CISZS solar cells is evaluated individually through Silvaco-Atlas simulation software in terms of measures such as power conversion efficiency, open-circuit voltage (Voc), the density of short-circuit current (Jsc) and fill-factor (FF). The CISZS-based solar cells show an average conversion efficiency of 23.5% (i.e., 4.94% higher than the efficiency of CIS solar cell) with Voc = 0.596V, Jsc = 23.61mA/cm2 and FF = 0.84 under AM 1.5G with a power density of 100mW/cm2 . The achieved power conversion efficiency indicates the greatest performances of the QDS solar cells. These non-toxic photovoltaic devices reveal better optical and electrical properties than toxic lead and cadmium chalcogenide quantum dots absorbers.