Two-dimensional (2D) Bi₂O₂Se nanosheets, as an emerging ternary layered semiconductor, exhibit promising potential for photodetection owing to their moderate bandgap, high carrier mobility, and excellent environmental stability. However, their intrinsically high carrier concentration typically results in elevated dark currents and sluggish response speeds, thereby limiting further performance enhancement. To synergistically optimize both the response speed and sensitivity, we fabricated n-type Bi₂O₂Se nanosheets via chemical vapor deposition (CVD) and integrated them into a Bi₂O₂Se/InSe semi-vertical heterojunction photodetector featuring a single-sided depletion region. Benefitting from the type-II band alignment and the graphene bottom electrode, photogenerated carriers are efficiently separated and rapidly extracted. This design simultaneously shortens the carrier transit time and suppresses recombination, enabling the device to achieve high sensitivity (responsivity R of 0.47 A/W, detectivity D* of 3.21 × 10¹² Jones, external quantum efficiency (EQE) of 166.09%) while maintaining ultrafast response characteristics (rise/fall times of 48.5/41.7 μs). The photodetector exhibits broadband self-powered operation across ultraviolet (UV) to near-infrared wavelengths (300–1050 nm). These results highlight the significant potential of Bi₂O₂Se/InSe semi-vertical heterojunctions for high-performance, low-power, self-powered broadband photodetectors spanning the UV–visible–near infrared ray (UV–Vis–NIR) spectrum.

Near-space communication network (NS-ComNet), as an indispensable component of sixth-generation (6G) and beyond mobile communication systems and the space–air–ground–sea integrated network (SAGSIN), demonstrates unique advantages in wide-area coverage, long-endurance high-altitude operation, and highly flexible deployment. This paper presents a comprehensive review of NS-ComNet for 6G and beyond era. Specifically, by contrasting satellite, low-altitude unmanned aerial vehicle (UAV), and terrestrial communications, we first elucidate the background and motivation for integrating NS-ComNet into 6G network architectures. Subsequently, we review the developmental status of near-space platforms, including high-altitude balloons, solar-powered UAVs, and stratospheric airships, and analyze critical challenges faced by NS-ComNet. To address these challenges, the research focuses on key enabling technologies such as topology design, resource and handover management, and multiobjective joint optimization, with particular emphasis on artificial intelligence techniques for NS-ComNet. Finally, envisioning future intelligent collaborative networks that integrate NS-ComNet with satellite–UAV–terrestrial systems, we explore promising directions. This paper aims to provide technical insights and research foundations for the systematic construction of NS-ComNet and its deep deployment in the 6G and beyond era.