Infrared photodetectors play an essential role in diverse military and civilian applications. Nevertheless, traditional infrared detection materials often suffer from inherent limitations, such as fixed bandgaps and stringent low-temperature operational requirements. The emergence of two-dimensional (2D) materials has revolutionized infrared detection technology, enabling the development of efficient room-temperature photodetectors. Among various 2D materials, black phosphorus (BP) has attracted considerable attention due to its narrow direct bandgap, tunable electronic properties, and exceptional hole mobility. These unique attributes endow BP-based infrared photodetectors with superior performance, including ultrafast response times, broad detection spectral ranges, and remarkably low dark currents. This review systematically summarizes recent advancements in material synthesis techniques, underlying device principles, and performance optimization strategies of BP infrared photodetectors. Additionally, it critically addresses ongoing challenges and offers a comprehensive perspective, laying a solid theoretical foundation and practical roadmap for advancing next-generation high-performance infrared photodetection technologies.

This study proposes a feasible and scalable production strategy to naturally obtain aligned platinum diselenide (PtSe₂) nanoribbon arrays with anisotropic conductivity. The anisotropic properties of two-dimensional (2D) materials, especially transition-metal dichalcogenides (TMDs), have attracted great interest in research. The dependence of physical properties on their lattice orientations is of particular interest because of its potential in diverse applications, such as nanoelectronics and optoelectronics. One-dimensional (1D) nanostructures facilitate many feasible production strategies for shaping 2D materials into unidirectional 1D nanostructures, providing methods to investigate the anisotropic properties of 2D materials based on their lattice orientations and dimensionality. The natural alignment of zigzag (ZZ) PtSe₂ nanoribbons is experimentally demonstrated using angle-resolved polarized Raman spectroscopy (ARPRS), and the selective growth mechanism is further theoretically revealed by comparing edges and edge energies of different orientations using the density functional theory (DFT). Back-gate field-effect transistors (FETs) are also constructed of unidirectional PtSe₂ nanoribbons to investigate their anisotropic electrical properties, which align with the results of the projected density of states (DOS) calculations. This work provides new insight into the anisotropic properties of 2D materials and a feasible investigation strategy from experimental and theoretical perspectives.

A high-performance heterojunction photodetector is formed by combining an n-type Si substrate with p-type monolayer WSe₂ obtained using physical vapor deposition. The high quality of the WSe₂/Si heterojunction is demonstrated by the suppressed dark current of 1 nA and the extremely high rectification ratio of 10⁷. Under illumination, the heterojunction exhibits a wide photoresponse range from ultraviolet to near-infrared radiation. The introduction of graphene quantum dots (GQDs) greatly elevates the photodetective capabilities of the heterojunction with strong light absorption and long carrier lifetimes. The GQDs/WSe₂/Si heterojunction exhibits a high responsivity of ~ 707 mA·W^–1, short response time of 0.2 ms, and good specific detectivity of ~ 4.51 × 10⁹ Jones. These properties suggest that the GQDs/WSe₂/Si heterojunction holds great potential for application in future high-performance photodetectors.