CsPbI₃ photodetectors: Insights from SCAPS numerical modelling

Perovskite-based photodetectors are of growing interest due to their high absorption coefficients, tuneable bandgaps, and superior optoelectronic properties. In this work, we employed SCAPS-1D numerical simulations to design and optimize a vertical photodetector using CsPbI₃ as the active absorber layer. The optimization was performed systematically by varying the material choices and physical parameters of the electron transport layer (ETL), hole transport layer (HTL), and the perovskite layer. Among the investigated candidates, WS₂ and Cu 2 O were identified as the optimal ETL and HTL, respectively, owing to their favourable energy level alignment and charge transport properties. Key device parameters, including layer thickness, doping concentration, defect density, interfacial states, and electrode work functions, were thoroughly analysed. The optimized device architecture, FTO/WS 2 /CsPbI 3 /Cu 2 O/Au, exhibited a short-circuit current density of 20.126 mA/cm 2 , a responsivity of 0.48 A/W, and a specific detectivity of 9.5 × 10 10 Jones under a bias of -0.5 V. The peak photoresponse was observed in the 650-700 nm wavelength range, with an overall power conversion efficiency of 16.64%. These results demonstrate that simulation-driven optimization can effectively guide the design of high-performance perovskite photodetectors. The findings highlight the potential of CsPbI₃-based vertical devices for visible-light applications, providing a framework for the experimental development of efficient and stable photodetectors.