Fully solution-processed semi-transparent, flexible, self-powered broadband photodetector based on two-dimensional PbI2 nanoplates

Abstract

The use of multiple detectors to recognize various wavelengths often complicates integration systems and reduces overall detection efficiency. Numerous key challenges exist in fabricating a single photodetector capable of broad-spectrum response under unbiased conditions while maintaining transparency, flexibility, and compatibility with high-density integration. These characteristics are particularly important for next-generation applications in the Internet of Things as well as in transparent and wearable optoelectronic devices. In this study, a broadband ultraviolet-to-visible photodetector based on PbI2 nanosheets was fabricated through a fully solution-processed approach using PEDOT:PSS as the transparent top electrode. This structure provides excellent optoelectronic performance and mechanical flexibility without compromising transparency. The intrinsic built-in potential enables self-powered operation. The fabricated photodetector exhibited a responsivity of 10.8 mA/W, a specific detectivity of 1.86 × 1011 Jones, and external quantum efficiency of 2.54 % under 455 nm illumination in unbiased conditions. It also demonstrated excellent cycling stability under repeated light on/off switching, a rapid response speed of 200/110 ms, and wide spectral sensitivity in the 365–530 nm range. Furthermore, the flexible devices maintained stable performance under different bending angles (30°, 60°, 90°, and 120°) and continuous bending cycles (1200), confirming their potential for large-area flexible and wearable optoelectronic applications.