Self‐Confined Growth of Ultrathin 2D Nonlayered Wide‐Bandgap Semiconductor CuBr Flakes

Abstract

2D planar structures of nonlayered wide‐bandgap semiconductors enable distinguished electronic properties, desirable short wavelength emission, and facile construction of 2D heterojunction without lattice match. However, the growth of ultrathin 2D nonlayered materials is limited by their strong covalent bonded nature. Herein, the synthesis of ultrathin 2D nonlayered CuBr nanosheets with a thickness of about 0.91 nm and an edge size of 45 µm via a controllable self‐confined chemical vapor deposition method is described. The enhanced spin‐triplet exciton (Zf, 2.98 eV) luminescence and polarization‐enhanced second‐harmonic generation based on the 2D CuBr flakes demonstrate the potential of short‐wavelength luminescent applications. Solar‐blind and self‐driven ultraviolet (UV) photodetectors based on the as‐synthesized 2D CuBr flakes exhibit a high photoresponsivity of 3.17 A W−1, an external quantum efficiency of 1126%, and a detectivity (D*) of 1.4 × 1011 Jones, accompanied by a fast rise time of 32 ms and a decay time of 48 ms. The unique nonlayered structure and novel optical properties of the 2D CuBr flakes, together with their controllable growth, make them a highly promising candidate for future applications in short‐wavelength light‐emitting devices, nonlinear optical devices, and UV photodetectors.

Space‐Confined Growth of 2D InI Showing High Sensitivity in Photodetection

“…[ 34 ] On account of its high crystalline quality and low defects, the fluorescent lifetime of the InI flake is utilized and fitted as 0.34 ns (Figure 3c), marginally more protracted than previously reported high‐quality 2D materials. [ 35–38 ] Furthermore, temperature‐dependent PL measurement is also carried out to get more information about the carrier’s trap states in the 80–300 K temperature range using an excitation wavelength of 532 nm; as expected, the PL intensity decreases drastically as the temperature increases from 80 to 300 K, indicating a thermal quenching effect as shown in pseudocolor map (Figure 3d) and Figure 3e shows the temperature‐dependent PL intensity curve. Figure 3f illustrates that the exciton emission peak blue‐shifted from 2.008 to 1.988 eV due to the lattice expansion as the temperature increases.…”

Growth of 2D MoP single crystals on liquid metals by chemical vapor deposition

“…SHG refers to an NLO effect that two photons with the same frequency encounter with nonlinear materials producing one double frequency photon (Fig. 3a) [33]. The experimental setup of SHG measurement is shown in Fig.…”

Recent Progress of Heterojunction Ultraviolet Photodetectors: Materials, Integrations, and Applications

“…Copyright 2012, Wiley‐VCH. b) Morphologies and device performance of UV detectors based on large‐size wide‐bandgap 2D crystals (top: NiPS 3 ,144 bottom: CuBr145). Reproduced with permission 144.…”

“…Reproduced with permission 144. Copyright 2017, Wiley‐VCH and reproduced with permission 145. Copyright 2019, Wiley‐VCH.…”

“…More impressively, ultrathin CuBr nanoflakes (0.91 nm) give an edge size of 45 µm and exhibits excellent solar‐blind UV photoconductivity (Figure 5b). 145 Although current reports have not focused on the vdWs heterostructures based on large‐bandgap 2D crystals, these materials have the potential to form 2D sandwich heterojunction photodiodes.…”