Two-dimensional layered material photodetectors: what could be the upcoming downstream applications beyond prototype devices?

With distinctive advantages spanning excellent flexibility, rich physical properties, strong electrostatic tunability, dangling-bond-free surface, and ease of integration, 2D layered materials (2DLMs) have demonstrated tremendous potential for photodetection. However, to date, most of the research enthusiasm has been merely focused on developing novel prototype devices. In the past few years, researchers have also been devoted to developing various downstream applications based on 2DLM photodetectors to contribute to promoting them from fundamental research to practical commercialization, and extensive accomplishments have been realized. In spite of the remarkable advancements, these fascinating research findings are relatively scattered. To date, there is still a lack of a systematic and profound summarization regarding this fast-evolving domain. This is not beneficial to researchers, especially researchers just entering this research field, who want to have a quick, timely, and comprehensive inspection of this fascinating domain. To address this issue, in this review, the emerging downstream applications of 2DLM photodetectors in extensive fields, including imaging, health monitoring, target tracking, optoelectronic logic operation, ultraviolet monitoring, optical communications, automatic driving, and acoustic signal detection, have been systematically summarized, with the focus on the underlying working mechanisms. At the end, the ongoing challenges of this rapidly progressing domain are identified, and the potential schemes to address them are envisioned, which aim at navigating the future exploration as well as fully exerting the pivotal roles of 2DLMs towards the practical optoelectronic industry.

Emerging Schemes for Advancing 2D Material Photoconductive-Type Photodetectors.

By virtue of the widely tunable band structure, dangling-bond-free surface, gate electrostatic controllability, excellent flexibility, and high light transmittance, 2D layered materials have shown indisputable application prospects in the field of optoelectronic sensing. However, 2D materials commonly suffer from weak light absorption, limited carrier lifetime, and pronounced interfacial effects, which have led to the necessity for further improvement in the performance of 2D material photodetectors to make them fully competent for the numerous requirements of practical applications. In recent years, researchers have explored multifarious improvement methods for 2D material photodetectors from a variety of perspectives. To promote the further development and innovation of 2D material photodetectors, this review epitomizes the latest research progress in improving the performance of 2D material photodetectors, including improvement in crystalline quality, band engineering, interface passivation, light harvesting enhancement, channel depletion, channel shrinkage, and selective carrier trapping, with the focus on their underlying working mechanisms. In the end, the ongoing challenges in this burgeoning field are underscored, and potential strategies addressing them have been proposed. On the whole, this review sheds light on improving the performance of 2D material photodetectors in the upcoming future.

Quantum tailoring for polarization-discriminating Bi2S3 nanowire photodetectors and their multiplexing optical communication and imaging applications.

In this study, cost-efficient atmospheric pressure chemical vapor deposition has been successfully developed to produce well-aligned high-quality monocrystalline Bi2S3 nanowires. By virtue of surface strain-induced energy band reconstruction, the Bi2S3 photodetectors demonstrate a broadband photoresponse across 370.6 to 1310 nm. Upon a gate voltage of 30 V, the responsivity, external quantum efficiency, and detectivity reach 23 760 A W-1, 5.55 × 106%, and 3.68 × 1013 Jones, respectively. The outstanding photosensitivity is ascribed to the high-efficiency spacial separation of photocarriers, enabled by synergy of the axial built-in electric field and type-II band alignment, as well as the pronounced photogating effect. Moreover, a polarization-discriminating photoresponse has been unveiled. For the first time, the correlation between quantum confinement and dichroic ratio is systematically explored. The optoelectronic dichroism is established to be negatively correlated with the cross dimension (i.e., width and height) of the channel. Specifically, upon 405 nm illumination, the optimized dichroic ratio reaches 2.4, the highest value among the reported Bi2S3 photodetectors. In the end, proof-of-concept multiplexing optical communications and broadband lensless polarimetric imaging have been implemented by exploiting the Bi2S3 nanowire photodetectors as light-sensing functional units. This study develops a quantum tailoring strategy for tailoring the polarization properties of (quasi-)1D material photodetectors whilst depicting new horizons for the next-generation opto-electronics industry.