Working Voltage Switching the Photo-/Thermo-Electric Effect for Distinct Ultraviolet and Infrared Signal Detection.

Liu, Shilin; Ding, Yijing; Rong, Wenzhe; Xu, Yi; Li, Yuwei; Onwudiwe, Damian Chinedu; Bae, Byung Seong; Ertuğrul, Mehmet et al. · ACS Nano · 2024

basic_science · Level V

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Abstract

The combination of sensing invisible ultraviolet photons and infrared radiation can significantly enhance target recognition by offsetting their own limit in a short sensing range and poor spatial resolution. However, the difference in their wavelength sets unique requirements for sensing materials and devices, which makes it hard to establish their implementation in a single detector. In this work, we present the design of a single detector with CH<sub>3</sub>NH<sub>3</sub>PbCl<sub>3</sub> (MAPbCl<sub>3</sub>) for distinguishing ultraviolet and IR signals by switching its operating mode in the photo-/thermo-electric effect. The large optical band gap of ∼3.2 eV in MAPbCl<sub>3</sub> ensures the response toward an ultraviolet photon, while its efficient thermoelectric effect allows the sensing of an IR signal. As a result, the detector exhibits a specific detectivity of 4.5 × 10<sup>12</sup> Jones for 395 nm ultraviolet photons under 0 V, while under the working voltage of 2.5 V, it demonstrates a superior temperature coefficient of resistance of -3.7% K<sup>-1</sup>, a specific detectivity of 4.8 × 10<sup>8</sup> Jones, and a limit of detection of 0.58 mW/cm<sup>2</sup> for 4 μm photons. The functionality of the switching response to ultraviolet or IR photons by working voltage allows background subtraction and enhances the target discrimination in the imaging.