Solar-blind ultraviolet photodetectors operating in the waveband of 200-280 nm become critical components in modern optoelectronic systems due to their near-zero background interference, strong environmental adaptability, high sensitivity, fast response speed, and strong anti-jamming capability. These advantages enable their widespread use in high-value applications such as military reconnaissance, missile tail-flame detection, early fire warning, industrial pollutant monitoring, secure optical communication, and biomedical detection. As the core functional layer of photodetectors, the intrinsic properties of photosensitive materials directly determine the overall performance of optoelectronic devices, including responsivity, external quantum efficiency, detectivity, response time, dark current, and long-term stability. However, conventional semiconductor and inorganic photoelectric materials used in solar-blind detection suffer from inherent limitations, such as narrow spectral absorption range, low photon-to-electron conversion efficiency, poor structural stability under continuous light irradiation, high dark current noise, and incompatibility with low-cost fabrication. These drawbacks severely restrict their further application in high-performance and multi-scenario solar-blind photodetection systems.

Rare-earth ion-doped optoelectronic materials have attracted recent attention as next-generation solar-blind detection media due to their unique electronic structure and excellent optical controllability. Benefiting from the shielded 4f electron configuration, rare-earth ions exhibit abundant and sharp energy levels, long fluorescence lifetime, and characteristic narrow-band emission. Through various efficient energy transfer pathways, including resonant radiative energy transfer, resonant non-radiative energy transfer, multi-phonon assisted energy transfer, and cross relaxation, rare-earth-doped materials can efficiently capture, convert, and modulate high-energy solar-blind UV photons. In particular, the down-conversion and quantum-cutting luminescence mechanisms allow one high-energy UV photon to be converted into one or more low-energy photons in the visible or near-infrared region, which can be easily detected by conventional silicon-based photodetectors. This photophysical conversion process significantly improves photon utilization efficiency, enhances optoelectronic response, and breaks through the performance bottlenecks of conventional solar-blind materials.

This review represents recent research progress on rare-earth-doped materials for high-performance solar-blind photodetection based on energy transfer. First, the fundamental photophysical properties of rare-earth ions are introduced, including their energy level structure, electron transition characteristics, and classification of energy transfer mechanisms, with a special emphasis on the down-conversion and quantum-cutting processes that dominate efficient UV-to-visible conversion. Second, rare-earth doping systems are categorized into single-doping, co-doping, and multi-doping architectures, and the photoelectric characteristics, energy transfer paths, and performance differences among various ion combinations are discussed. In addition, four major matrix material systems, i.e., oxides, fluorides, oxyfluorides, and nanocrystals, are comprehensively evaluated, focusing on their bandgap width, phonon energy, structural stability, defect regulation ability, and compatibility with rare-earth ion doping.

Furthermore, the typical structures and working principles of traditional solar-blind photodetectors are introduced, including photoconductive detectors, photovoltaic detectors, and avalanche photodiodes. On this basis, three major efficiency-enhancement mechanisms introduced by rare-earth energy transfer are revealed, i.e., spectral absorption expansion and efficient photon capture, full-process carrier dynamic regulation including separation, transport and recombination, and material stability reinforcement and dark current suppression through defect passivation and interface optimization. Combined with representative device cases reported in recent years, this review further elaborates performance optimization strategies from four key dimensions, i.e., photoelectric response characteristics, response time and dynamic performance, long-term structural and environmental stability, and noise suppression and detectivity improvement.