Wang Dong, Cheng Qikuan, Xia Weibang, Tan Yongyao, Yu Kexuan, Zhang Lu, Li Guigang, Liu Rong, Wang Wei, Xu Linjuan, Wu Suli, Liu Yang, Wang Yunming, Zhou Huamin
State Key Laboratory of Material Processing and Die & Mould Technology, Huazhong University of Science & Technology, Wuhan, China.
Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Nat Commun. 2025 May 31;16(1):5064. doi: 10.1038/s41467-025-60393-1.
Constructing micro-/nanostructure-modulated photofields in upconversion devices to absorb low-energy photons and emit high-energy light is revolutionary for bioimaging, lasers, and photovoltaics, with proven capability to boost upconversion luminescence (UCL) by orders of magnitude. However, photoenergy dissipation and inadequate absorption result in excitation thresholds exceeding 1 mW/cm, which exceeds retinal safety limits and hinders wearable upconversion optics. Here, we report the use of upconversion core-shell microsphere-induced infrared field convergence, NaYF:Yb,Er shell-based resonant cavities for multiple reflection-absorption-upconversion and photonic crystal amplifiers to improve UCL intensity three orders of magnitude, and achieve ultralow threshold (0.0025 mW/cm). The 500 nm upconversion core-shell microspheres generated 1200-fold stronger electric field through concentrated photofield and attained 8-fold infrared absorption with a forward/backward emission ratio of 150. Fabricated upconversion contact lenses significantly improved dark-light imaging clarity and vision restoration in retinal degeneration rabbits. Microsphere-mediated directional upconversion strategy maximizes photoenergy utilization, paving the way for high-performance wearable upconversion devices.
在光上转换器件中构建微/纳米结构调制的光场，以吸收低能量光子并发射高能量光，这对于生物成像、激光和光伏技术具有革命性意义，已被证明有能力将上转换发光（UCL）提高几个数量级。然而，光能耗散和吸收不足导致激发阈值超过1 mW/cm，这超过了视网膜安全极限，阻碍了可穿戴上转换光学器件的发展。在此，我们报告了利用上转换核壳微球诱导的红外场收敛、基于NaYF:Yb,Er壳的共振腔进行多次反射-吸收-上转换以及光子晶体放大器，将UCL强度提高三个数量级，并实现超低阈值（0.0025 mW/cm）。500 nm的上转换核壳微球通过集中光场产生了强1200倍的电场，并实现了8倍的红外吸收，前后发射比为150。制造的上转换隐形眼镜显著提高了视网膜变性兔的暗光成像清晰度和视力恢复。微球介导的定向上转换策略最大限度地提高了光能利用率，为高性能可穿戴上转换器件铺平了道路。
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