Theoretical Sagacity of an Efficient Cu₂ZnGeSe₄‐Based Thin Film Solar Cell and Photodetector

Abstract Copper zinc germanium selenide (Cu 2 ZnGeSe 4 ) based dual‐heterojunction (DH) photovoltaic (PV) and photodetector (PD) devices are probed mathematically by solar cell capacitance simulator (SCAPS‐1D), where CdS and ZnTe are employed as the buffer and back surface field (BSF). The research initially aimed to optimize both the solar cell and photodetector performance by systematically adjusting crucial physical parameters such as breath, carrier dopant level, and flaw concentration defects within each energetic layer. Under optimized conditions, the suggested photonic device achieves an incredible power conversion efficiency (PCE) of 31.06% alongside an open circuit voltage ( V OC ) of 1.16 V, short circuit current ( J SC ) of 30.70 mA cm −2 , and fill factor (FF) is 87.52%, responsivity (R) 0.58 A W −1 and detectivity (D * ) 8.28 × 10 17 Jones. ZnTe plays a vital role in this structure, which built a barrier at the Cu 2 ZnGeSe 4 /ZnTe heterojunction interface and contributes to the reduced surface recombination velocity. The results suggest promising prospects for future manufacturing of high‐performance Cu 2 ZnGeSe 4 ‐based solar cells and photodetector.