Self-powered and highly stable broadband photodetectors based on spin-coated PbWO₄/Si heterostructures with 720-day environmental robustness

Lead Tungstate (PbWO₄) has been extensively utilized as a high-performance scintillator in high-energy physics due to its superior radiation hardness and fast response time. However, its potential for direct, high-performance photodetection has remained largely untapped. This work bridges this gap by demonstrating, for the first time, a high-sensitivity broadband photodetector based on a PbWO₄/Si heterojunction including UV (365 nm), visible, and IR (850 nm) regions. Beyond its traditional role in radiation sensing, we show that PbWO₄ can be repurposed for versatile optoelectronic applications. Fabricated via a cost-effective spin-coating method, the device exhibits exceptional performance across the UV, visible, and IR regions. While the highest response (R) value was 137 mA/W under white light, measurements at different wavelengths showed that the R value reached 1416 mA/W under 356 nm UV light. Optimum detectivity values for white light (for 125 mW/cm²) and 365 nm UV light were obtained as 7.85 × 10¹⁰ and 9.21 × 10¹¹ Jones, respectively, at zero bias. The external quantum efficiency (EQE) value was obtained as 466(%) at 365 nm. The device exhibited a remarkable maturation in performance after 205 days of ambient storage, with the dark current decreasing by 48.81% and the responsivity enhancing by up to 303%, demonstrating exceptional long-term stability and environmental robustness. The I–V characteristics of the device recorded after 720 days showed no significant deviation from the results obtained at 205 days. These findings not only expand the application scope of PbWO₄ into the broadband optoelectronics domain but also provide a robust framework for developing stable, low-cost, and high-efficiency heterojunction detectors.