High‐Performance Visible‐Light Photodetectors built on 2D‐Nanoplate‐Assembled Large‐Scale BiI₃ Films

Abstract

detecting abilities over a wide spectral range from ultraviolet to infrared and even terahertz. [8][9][10][11][12] In the past, the investigations on 2DLMs devices (including photodetectors) focused mainly on the nanoscale samples, such as the devices processed on exfoliated monolayers, nanosheets, or nanoplates, for fundamental researches. While recently, driven by the growing demands for practically using of those promising devices, great efforts have been made to prepare large-scale continuous 2DLMs films. [13][14][15] For instance, both chemical vapor deposition and solution-processing methods were used to produce waferscale graphene and TMDs films, [15][16][17] and some novel liquid metal facilitated synthesis approaches were also applied to synthesize large-scale films of 2D metal oxides and their derivatives. [18][19][20][21] Some of those films have been demonstrated beneficial to support the large-area arrays or the integrated devices which require high sample density, good thickness uniformity, and controllable location. [13][14][15][16][17][18][19] Unfortunately, there always remains a trade-off between the film size and the performances of the devices on them. In the aspect of photodetectors, most of the devices built on large-scale films have attenuated qualities comparing with those ones produced on nanoscale samples. [22][23][24] For example, the responsivity of the MoS 2 film photodetectors may decay of two orders of magnitude than that of the nanoscale devices . [8,23] Thus, it still remains a challenge to grow 2DLMs films which guarantee not only large lateral size but also excellent device performances. In view of this, we propose a possible scheme that assembling high-quality nanolayers (which can ensure outstanding photodetecting capability for the nanoscale detectors processed on them) into a nanostructured film may bring out a win-win result between both sides. This idea is implemented by synthesizing large-area films (1 × 1 cm 2 ) made up of vertically grown BiI 3 nanoplates which have been proved to support excellent nanoscale photodetectors. [12] The reproducible and sizeable photoresponses of the photodetectors fabricated on such films demonstrate equivalent performances with the single BiI 3 nanoplate-based ones and indicate hopeful applications of such BiI 3 films for visible-light detecting.As shown in the scanning electron microscopy (SEM) image in Figure 1a, the BiI 3 films used to construct the photodetecting devices consist of a large number of vertical and oblique nanoplates grown via physical vapor deposition (PVD) method. An enlarged SEM image (Figure 1b) revealsThe growth of large-scale films forms the cornerstone for future integrated photodetection applications of 2D materials. However, there is still an unwelcome trade-off between the size of these films and the performances of devices fabricated using them. To deal with this issue, a possible scheme for film assembly is proposed using high-quality nanolayers to achieve both outstanding device performance and large film ar...

Pressure Engineering for Extending Spectral Response Range and Enhancing Photoelectric Properties of Iodine

“…In recent years, emerging 2D materials including black phosphorus, [1,2] MXenes, [3,4] graphdiyne, [5,6] transitionmetal dichalcogenides, [7,8] and metal halides MX n (M = metal, X = Cl, Br, I, n = 2, 3) [9][10][11][12][13][14] have attracted tremendous interest due to their excellent electrical, optical, and magnetic properties. Among these materials, 2D layered binary iodides with bandgaps in the range of 1.1-1.7 eV, that is, BiI 3 , [9][10][11] PbI 2 , [12] and RhI 3 , [13,14] have been found to have excellent properties for optoelectronic applications. Similar to these binary iodides, iodine is also a 2D layered semiconductor, and atomically thin iodine nanosheets have been successfully fabricated via a liquid-phase exfoliation method.…”

Alternative Lone‐Pair ns2‐Cation‐Based Semiconductors beyond Lead Halide Perovskites for Optoelectronic Applications

“…reported a photodetector based on vertical BiI 3 nanoplates, which achieved a remarkable specific detectivity of 1.2 × 10 12 Jones and a fast stable photoresponse (3/9 ms for raise/decay times); [ 160 ] subsequently, they built a device based on a complex structure consisting of vertically grown BiI 3 nanoplates, which was able to further enhance detectivity up to 1.65 × 10 12 Jones. [ 38 ] The performances of photodetector based on high‐quality BiI 3 film, including responsivity and detectivity, were comparable with devices constructed by other 2D materials (Figure 8c). In addition, BiI 3 can be applied for the photocatalytic hydrogen generation.…”

“…Reproduction with permission. [ 38 ] Copyright 2019, Wiley‐VCH. d) Curves of cumulative hydrogen production for the BiI 3 and BiI 3 –Ag films under simulated solar irradiation (left panel), Scheme showing two competing mechanisms: 1) the reduction from I − to IO 3 − and 2) the reduction from H + to H 2 .…”

2D Layered Material Alloys: Synthesis and Application in Electronic and Optoelectronic Devices

“…[ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ] In broad terms, 2DLMs represent the emerging atomically thin materials where intramolecular interactions are covalent/ionic forces, whereas the intermolecular interactions are van der Waals (vdW) forces. Inspiringly, the scientific communities have by far identified and produced a broad catalog of 2DLMs beyond graphene, represented by group 15 semiconductors, [ 18 ] nitrides, [ 7 ] transition metal dichalcogenides (TMDCs), [ 19 , 20 , 21 , 22 ] post‐transition metal chalcogenides, [ 23 , 24 ] halides, [ 25 , 26 , 27 , 28 ] multi‐elemental compounds, [ 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ] just to name a few. Benefiting from the prominent electrostatic tunability, dangling‐bond‐free top/bottom interface, intrinsic exemption to short‐channel effects, spatially confined structures, reasonably high carrier mobility, outstanding mechanical strength, and strong interactions with light, these fascinating 2D building blocks have come under the limelight of the nano‐electronics and nano‐optoelectronics realms.…”