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.
Self-powered photodetectors with excellent figure-of-merits, fast response speed, and broadband detection capability have drawn tremendous research interest. However, it is still challenging to develop excellent light-absorbing materials as photodetectors with...
A novel silane coupling agent grafting TiO2 nanorod arrays (C3H8NSi‐TiO2 NRAs)/n‐Si heterojunction is introduced. A built‐out electric field is created on the surface of TiO2 NRAs by silane coupling agent modifications, which can promote photo‐generated carriers separation so that the C3H8NSi‐TiO2 NRAs/n‐Si heterojunction shows excellent self‐powered broadband photoresponse properties. Especially under 900 nm illumination, the self‐powered device demonstrates the responsivity (R), detectivity (D*), and sensitivity (S) of ≈7.76 A W−1, ≈5.22 × 1014 Jones, and ≈1.12 × 1010 cm2 W−1, respectively. Compared with that of the unmodified TiO2 NRAs/n‐Si heterojunction, the R, D*, and S are increased by two orders of magnitude. The results are mainly ascribed to the original built‐in electric field of heterojunction and the created built‐out electric field which jointly promote carriers separation and the unconventional porous electrode which plays a crucial role in collecting holes. The DFT calculations and TRPL results indicate the formation and carriers separation capability of the built‐out electric field. This design concept can be extended to the application of other varieties of metal oxide based photoelectric devices.
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