Self-driven PbSe thin-film mid-infrared detector for methane detection

Mid-infrared gas detection enables high selectivity and quantitative analysis, but its performance depends strongly on the photodetector serving as the optical receiver. PbSe is a narrow-bandgap semiconductor with favorable photoresponse characteristics in the mid-infrared region. However, existing PbSe photoconductive detectors generally require a relatively high external bias, which can introduce dark current and increase system power consumption. In this work, a solution-mediated grain-boundary engineering strategy was introduced to construct a self-driven PbSe thin-film detector. Under self-driven operation, the device achieved broadband photoresponse over 2.7–9.7 μm, a low current noise amplitude spectral density of 1.02 × 10 -14 A Hz −1/2 , and a specific detectivity of 1.24 × 10 9 Jones at 3.3 μm. During 3000 s of continuous optical modulation, the normalized photovoltage output retained 99.94% of its initial amplitude, demonstrating excellent long-term operational stability. Based on the characteristic absorption of CH 4 near 3.3 μm, the detector was integrated as the receiver in an infrared absorption-based gas detection system, enabling distinguishable concentration-dependent responses over 17–4000 ppm. This study provides a feasible and low-cost strategy for developing stable, low-power, self-driven room-temperature mid-infrared detectors and demonstrates their potential for infrared spectroscopic gas sensing.