Multilayered PdTe2/thin Si heterostructures as self-powered flexible photodetectors with heart rate monitoring ability

Two-dimensional layered material/semiconductor heterostructures have emerged as a category of fascinating architectures for developing highly efficient and low-cost photodetection devices. Herein, we present the construction of a highly efficient flexible light detector operating in the visible-near infrared wavelength regime by integrating a PdTe₂ multilayer on a thin Si film. A representative device achieves a good photoresponse performance at zero bias including a sizeable current on/off ratio exceeding 10⁵, a decent responsivity of ~343 mA/W, a respectable specific detectivity of ~2.56 × 10¹² Jones, and a rapid response time of 4.5/379 μs, under 730 nm light irradiation. The detector also displays an outstanding long-term air stability and operational durability. In addition, thanks to the excellent flexibility, the device can retain its prominent photodetection performance at various bending radii of curvature and upon hundreds of bending tests. Furthermore, the large responsivity and rapid response speed endow the photodetector with the ability to accurately probe heart rate, suggesting a possible application in the area of flexible and wearable health monitoring.