High-speed ultraviolet photodetectors based on 2D layered CuInP₂S₆nanoflakes

Although a lot of promising two-dimensional (2D) semiconductors with various bandgaps, represented by black phosphorus (0.3 eV), transition metal dichalcogenides (< 2 eV), and boron nitride (5 - 6 eV), have been extensively researched in photoelectronic and electronic devices, the spectrum of large bandgap materials is still very narrow, which limits the potential device applications in ultraviolet photodetection. The broad family of layered thio- and seleno-phosphates with wide and tunable bandgaps (1.3 - 3.5 eV) can complement the intermediate bandgaps from 1.6 to 4 eV, which can fill the gap between transition metal dichalcogenides and boron nitride. In this work, a high-performance ultraviolet photodetector based on multilayered CuInP2S6 was fabricated. It exhibits fast response times shorter than 0.5 ms, i.e., rise time ∼0.36 ms and fall time ∼0.44 ms for ultraviolet illumination (280 nm, 50 nW), which is superior than previously reported 2D layered-based UV detectors. Significantly, this photodetector also shows ultralow dark current (∼100 fA), a high on/off ratio (∼103), and a specific detectivity of 7.38 × 1010 Jones. Our results provide an excellent candidate for low power consumption and high-speed photodetection.