Bi2Se3–PtSe2 heterostructure ultrabroadband UV-to-THz negative photoconductive photodetectors with wide-temperature-range operation

Abstract

Ultra-broadband photodetectors have important applications in biomedical imaging, environmental monitoring, optical communication, space exploration, and other fields. Therefore, the need for their wide-temperature-range adaptation in extreme environments (e.g., infrared guidance and space exploration) is particularly urgent. However, existing technologies face a number of bottlenecks. First, traditional semiconductor detectors are limited to a single spectral response, meaning ultra-wideband detection requires multi-device integration, while in the terahertz band, there is a physical limitation of the mismatch between the photon energy and the material bandgap. Second, carrier scattering at high temperatures leads to a sudden drop in mobility and degradation of the optical response. Finally, the development of devices based on the negative photoconductivity effect is still in the exploratory stage, which limits their engineering applications. In this study, we innovatively integrated the photothermoelectric effect (PTE), Joule thermal effect (JHE) and photoinduced bolometric effect (PBE) multi-physics mechanisms by constructing a Bi₂Se₃–PtSe₂ heterojunction, which realizes broad-spectrum UV–terahertz (405 nm–0.1 THz) detection and stable operation in a wide temperature range of 183–501 K. Under zero bias, the device exhibits a self-powered positive optical response in the 405–1550 nm band based on the photothermoelectric effect. When bias voltage is applied, a negative photoconductive response is triggered by a synergistic Joule heating and optical radiothermal effect, with a peak responsivity (R) of 44.45–83.6 A W⁻¹, specific detection rate (D*) of up to 4.63 × 10⁷ Jones, and noise-equivalent power (NEP) as low as 1.37 × 10⁻¹³ W Hz^−1/2. Temperature characterization tests show that the R/D*/NEP was optimized to 78.19 A W⁻¹/5.75 × 10⁷ Jones/1.09 × 10⁻¹³ W Hz^−1/2 under 1550 nm illumination and at 183 K. Even at 501 K, the device maintains 11.24 A W⁻¹ responsivity and 7.9 × 10⁶ Jones detection sensitivity. The present work breaks through the limitations of the traditional negative photoconductivity effect in terms of the detection bandwidth and temperature stability through a multi-mechanism synergistic strategy, providing a theoretical basis and technical path for the design of a new generation of broad-spectrum photodetectors.