Homojunction‐Structured 2D Black Phosphorus Optoelectronic Device

Abstract The advent of 2D materials introduces greater diversity in the design of homojunction/heterojunction devices, resulting in a broader range of designs and significantly improved electronic transport and optical response. These materials are widely used in optoelectronic devices. Among these, 2D black phosphorus (BP) materials stand out due to its highly tunable bandgaps, which enable efficient optoelectronic conversion across different spectral ranges (from mid‐infrared to visible light) for the devices produced. The simplicity of homojunction fabrication, stable interfaces, and mature preparation techniques further enables BP homojunction devices to meet a wide array of optoelectronic application needs, such as light detection and modulation. Consequently, BP homojunction devices hold significant promise in the field of optoelectronics and are poised to become key players in the next generation of high‐performance optoelectronic devices. This article compares the similarities and differences between heterojunctions and homojunctions, categorizing and providing examples of 2D homojunctions, and provides an extensive overview of the preparation methods—including doping engineering, geometric construction, and electric field modulation—along with the principles and performances of BP‐based homojunctions. Finally, a comprehensive summary and outlook on the future of BP homojunction devices are presented.