High Performance Lead-Free Perovskite-Based Photodetector for Low-Light Intensity Detection in Biomedical Applications.

This work presents a comprehensive numerical study on a lead-free, tin-based perovskite photodetector (PPD) designed for low-light biomedical sensing applications. Using CH3NH3SnBr3 as the active absorber layer, we model a device architecture comprising FTO/CdZnS/CH3NH3SnBr3/Spiro-OMeTAD/Au, optimizing key parameters through combined SCAPS-1D and COMSOL Multiphysics simulations. We systematically investigate the influence of absorber thickness, defect density, donor doping, electric field distribution, series and shunt resistance, and interface properties to maximize optoelectronic performance. The optimized PPD achieves a peak responsivity of 0.55 A/W and a detectivity of 9.7 × 1014 Jones within the red-light spectral window (680-790 nm), demonstrating enhanced charge carrier lifetimes and effective interfacial charge extraction. These results highlight the potential of CH3NH3SnBr3 as an eco-friendly alternative to lead-based perovskites, advancing the development of high-sensitivity, low-illumination photodetectors for biomedical imaging and diagnostics.