Upgrading CZTSSe solar cell performance through numerical investigation of Cu-based hole transport layers

A material like CZTSSe, belonging to the Kesterite family, serves as a guiding light for researchers due to its ability to tunable bandgap and exhibit a high optical coefficient exceeding 10⁴ cm⁻¹, crucial for solar cell applications. These characteristics not only render it suitable for single-junction solar cells but also enhance its overall acceptance. Meanwhile, the material Cu₂ZnSn(S_x, Se_1-x)₄ (CZTSSe) has increasingly captivated the attention of researchers owing to its cost-effectiveness, eco-friendliness, high absorption coefficient, and adjustable bandgap. This paper explores the conventional structure of CZTSSe solar cells comprising Al:ZnO/Zn(O,S)/CZTSSe/different Cu-based HTL, underscoring the importance of identifying an optimal HTL. Consequently, a comparative analysis of solar cells with various HTLs is conducted, facilitated by the SCAPS-1D numerical simulation software for property evaluation and efficiency optimization. Furthermore, varying parameters such as absorber layer thickness, defect densities, doping concentrations, and temperature shed light on the responses of open-circuit voltage (V_OC), short-circuit current (J_SC), fill factor (FF), and efficiency (PCE) of the solar cell. Among different Cu-based HTLs, Cu₂O emerges as a promising candidate for maximizing CZTSSe-based solar cell performance. Additionally, the discussion delves into the impacts of layer parameters like thickness, doping density, and carrier concentrations. Following device optimization, considerations extend to operating temperature variations and the effects of series and shunt resistance. Notably, our endeavors culminate in cell performance metrics: efficiency = 30.65 %, short-circuit current density = 42.15 mA/cm², open-circuit voltage = 0.84 V, and fill factor = 85.60 %.