Liu Gaochao,Chen Weibin,Xiong Zhan,Wang Yuzhen,Zhang Shuai,Xia Zhiguo
High-power broadband near-infrared (NIR) light sources based on laser-excited phosphors are highly desirable for photonics applications in night vision, biomedical imaging and sensing; however, the inherent energy gap law poses a great challenge for the development of efficient NIR luminescent materials. Herein we report a translucent MgO:Cr 3+ ceramic fabricated by spark plasma sintering, which exhibits a broadband NIR emission peak at 810 nm, with an external quantum efficiency of 81% and ultra-high thermal conductivity of 52 W m –1 K –1 . When pumped with a blue laser, the MgO:Cr 3+ ceramic provides an output power exceeding 6 W with a light conversion efficiency of 29%. This laser-driven broadband NIR light source makes it possible to perform NIR imaging with a spatial resolution of 6 lp mm –1 , and is a promising technology for emerging imaging applications.
Large-grained perovskite films are critical for mitigating carrier recombination and ensuring device robustness. Here, we report a microgap thermal sublimation (MGTS) method for fabricating high-quality, large-grained CsCu2I3 films designed for air-stable UV photodetection. By engineering a submillimeter sublimation zone under low-vacuum conditions, our approach enables self-regulated deposition that yields densely packed, highly crystalline films with preferential (221) orientation on both crystalline GaN and amorphous glass substrates. Kinetic gas theory analysis suggests that our microgap configuration maintains a vapor collision probability below 40%, facilitating efficient precursor transport and uniform film growth with grain sizes exceeding 20 μm. The resulting CsCu2I3/GaN heterojunction UV photodetectors, operating in self-powered mode, achieve a responsivity of 106.34 mA/W, a detectivity of 9.24 × 1011 Jones, and rise/fall times of 4.12 μs/2.12 ms. Notably, the devices demonstrate picowatt-level detection limits and imaging capability. This work establishes MGTS as a scalable, cost-effective platform for developing air-stable, wide-bandgap copper halide perovskites for next-generation UV optoelectronics.
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