Design and Optimization of a High-Performance Self-Powered MXene–Perovskite Type-II Heterojunction Photodetector

The development of high-performance, self-powered, and lead-free photodetectors has attracted significant attention for next-generation optoelectronic applications. In this work, a novel Mo2TiC2/CsSnI3 staggered (type-II) heterojunction photodetector (MPH-PD) is designed, optimized, and simulated using COMSOL Multiphysics. The device consists of an FTO/Mo2TiC2/CsSnI3/Au architecture that demonstrates excellent optical confinement, strong visible-light absorption with quantum efficiency above 80%, favorable conduction- and valence-band offsets of 0.30 eV and 0.25 eV, efficient charge separation, and suppressed recombination. Under AM1.5G illumination, the optimized device exhibits a very high light-to-dark current ratio of 108 under reverse-bias conditions and 1013 at zero bias. The photodetector achieves an excellent responsivity of 0.38 A/W, a peak detectivity of 2.12 × 1015 Jones, and a minimum noise equivalent power of about 4.7 × 10−16 WHz−1/2 at a 550 nm wavelength of the incident spectrum. Furthermore, the temperature-dependent simulation revealed optimum performance near room temperature with maximized responsivity, and detectivity with minimized noise equivalent power. Based on these results, the proposed MPH-PD demonstrates its significant potential for lead-free, self-powered photodetection technologies and provides a promising approach for further experimental research.