Unveiling the Effect of CZTSSe Quantum Superlattice on the Interfacial and Optical Properties of CZTS Kesterite Solar Cell

Abstract

Research on Cu ₂ ZnSnS _x Se _4–x (CZTSSe) Kesterite solar cells has reached a critical point, despite a significant improvement in understanding of the limitations associated with these materials. However, the conversion efficiency of CZTSSe solar cells has yet to exceed 20%, primarily due to a relatively high voltage deficit compared to other well-established chalcogenide technologies. The primary limitation for open-circuit voltage (V _oc ) in CZTSSe solar cells is associated with the defect structure, including intrinsic defects and defect clusters within the bulk absorber film. Specifically, the unfavorable band structure and poor defect environment contribute to increased carrier recombination at the front interface, which is a major challenge. To mitigate the issues related to interface recombination and reduce the V _oc deficit, a promising and practical approach known as quantum superlattices (QSs) has been proposed. It demonstrates CZTSSe QSs in the CZTS absorber layer. In ideal case it provides an efficiency of 37.8% with a V _oc of 1.06V, which is far better as compared to previously existing chalcogeneide technologies. Also in this study a deep inside into the different types of defect engineering is provided in detail with the help of numerical simulation tool.