The flexible photodetector plays an important role in improving human medical health status. However, the narrow spectral detection range, poor stress stability, and non‐degradation of traditional flexible photodetectors greatly hinder the further development of wearable medical devices. In this paper, a novel flexible infrared photodetector is proposed for intelligent healthcare monitoring using high purity lead sulfide (PbS) nanoparticles on paper‐based flexible substrate synthesized by hydrothermal method and physical friction. The excellent performance of the detector is attributed to the 1.01 eV band gap and six‐arm stellate dendritic structure of PdS, a good combination between PbS and paper substrate via physical friction. As a result, our photodetector demonstrates wide‐spectrum detection capabilities from 365 to 1550 nm. The photodetector at 980 nm (50.4 μW cm−2) shows responsivity of 6.45 mA W−1, detectivity of 6.4 × 1010 Jones, response recovery time of 0.36 s/0.41 s, with good mechanical stability. By comparison, our detector has a wider detection range, better weak signal detection performance, and shorter response time than the performance of the former paper‐based detector. Furthermore, the paper‐based PbS photodetector as a dual‐wavelength photoplethysmography sensor is applied to analyze the oxygen saturation and develop an intelligent bandage to monitor wound healing. This paper‐based PbS photodetector has tremendous potential in the field of wearable medical devices and intelligent medical applications are expected.

Inorganic nanomaterials such as graphene, black phosphorus, and transition metal dichalcogenides have attracted great interest in developing optoelectronic devices due to their efficient conversion between light and electric signals. However, the zero band gap nature, the unstable chemical properties, and the low electron mobility constrained their wide applications. Bismuth oxyselenide (Bi2O2Se) is gradually showing great research significance in the optoelectronic field. Here, we develop a bismuth oxyselenide/p-silicon (Bi2O2Se/p-Si) heterojunction and design a self-powered and broadband Bi2O2Se/p-Si heterojunction photodetector with an ultrafast response (2.6 μs) and low dark current (10–10 A without gate voltage regulation). It possesses a remarkable detectivity of 4.43 × 1012 cm Hz1/2 W–1 and a self-powered photoresponse characteristic at 365–1550 nm (ultraviolet-near-infrared). Meanwhile, the Bi2O2Se/p-Si heterojunction photodetector also shows high stability and repeatability. It is expected that the proposed Bi2O2Se/p-Si heterojunction photodetector will expand the applications of Bi2O2Se in practical integrated circuits in the field of material science, energy development, optical imaging, biomedicine, and other applications.