Tailored bandgap grading in CsSnI3-xBrx all inorganic perovskite solar cells with 2D MXene electrodes: A path to high-efficiency photovoltaics

Abstract

The incorporation of lead in perovskite solar cell (PSC) designs poses substantial environmental risks. In this context, tin-based perovskites are the probable aspirant, for the design of PSC, which possess similar chemical properties as lead. Additionally, Cs⁺ inorganic perovskites are gaining traction due to impressive stable PV performance, and to address the stability concerns associated with hybrid perovskite material. This study delves into investigating the photovoltaic (PV) performance of bandgap graded CsSnI_3-xBr_x (x = 0 to 3) tin associated all-inorganic perovskite solar cell (TAI-PSC) using SCAPS-1D simulator. Moreover, this novel approach integrates 2D MXene as electrodes, eliminating the need for electron and hole transport layers (ETL/HTL), resulting in a more cost-effective PSC design. The proposed solar cell Zr₂C-F (Zirconium carbide, surface termination with fluorine atoms/CsSnI_3-xBr_x (x = 0 to 3)/Ta₄C₃-O (Tantalum carbide, surface termination with oxygen atoms) where CsSnI_3-xBr_x (x = 0 to 3) serves as a light harvest layer, exhibited variation in energy bandgap/affinity with bromide concentration x, while deploying bandgap grading. By optimizing the light absorption and charge carrier dynamics, bandgap grading enhances the photovoltaic (PV) performance of solar cells. The work function of adopted 2D MXene Zr₂C-F (as the top electrode) and Ta₄C₃-O (as the bottom electrode) is 4.01 eV and 5.36 eV, respectively. This work has adopted the parabolic and exponential-graded active layers, enhanced the light spectrum absorption and generating more electron-hole pairs (EHP). The PV performance of graded CsSnI_3-xBr_x (x = 0 to 3) TAI-PSC with 2D MXene layers is remarkable, achieving power conversion efficiencies (PCE) of 33.66 % for parabolic grading and 34.51 % for exponential grading, respectively. This investigation provides a window of opportunity for researchers to design ETL/HTL-free, cost-effective, ecologically friendly PSC, and underscores the potential of integrating 2D MXene as end electrodes.