High-performance flexible broadband photodetectors enabled by 2D Ta₂NiSe₅ nanosheets

Abstract Flexible broadband optoelectronic devices play a prominent role in the areas of daily life including wearable optoelectronic systems, health care, and bio-imaging systems. Two-dimensional (2D) narrow-bandgap materials with atomic thickness, adjustable bandgap, mechanical flexibility, as well as excellent optical and electrical properties exhibit great potential for applications in flexible optoelectronic devices. Here, we demonstrate a high-performance photodetector based on high-quality ternary Ta₂NiSe₅ nanosheets with a narrow bandgap of 0.25 eV. The photodetectors exhibit broadband photodetection capability in the visible-infrared (IR) spectrum (405–2200 nm) at room temperature. The maximum values of responsivity can reach up to 280 A W⁻¹ at the wavelength of 405 nm. Meanwhile, the high responsivity of 63.9 A W⁻¹ and detectivity of 3.8 × 10⁹ Jones are achieved at the wavelength of 2200 nm, respectively. In addition, the obtained Ta₂NiSe₅-based photodetector shows excellent flexibility and the photodetection performance is almost insignificantly degraded after 1000 bending cycles. These results indicate that the 2D Ta₂NiSe₅ semiconductor has great potential in future wearable IR optoelectronic devices.