Suo Hao, Zhao Peihang, Zhang Xin, Guo Yang, Guo Dongxu, Chang Jiwen, Chen Jiangkun, Li Panlai, Wang Zhijun, Wei Hanlin, Zheng Weilin, Wang Feng
Hebei Key Laboratory of Optic-electronic Information and Materials, College of Physics Science & Technology, Hebei University, Baoding, China.
Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong SAR, China.
Nat Commun. 2025 Apr 5;16(1):3249. doi: 10.1038/s41467-025-58587-8.
Lanthanide-doped nanocrystals are promising for photon frequency upconversion with substantial spectrum tunability. However, the utilization of the upconversion process has been constrained by low luminescence efficiency, which may further attenuate at elevated temperatures due to thermal quenching. Herein, we report a versatile strategy to boost upconversion luminescence across a wide temperature range by surface coordination of small organic molecules. Mechanistic investigations affirm that the organic surface layer passivates defects and isolates high-energy surface oscillators, thereby preventing the dissipation of excitation energy. The energy preserving effect becomes more prominent with increasing temperatures, especially in a humid environment. Accordingly, the upconversion emission of NaGdF:Yb/Tm nanocrystals is substantially enhanced in the ambient environment after ligand coordination, accompanied by an additional emission augmentation with increasing temperature to 443 K. By leveraging this anomalous optical response to thermal stimuli, we further establish full-color thermochromic upconversion switching for advanced anti-counterfeiting and logic encryption technologies.
镧系掺杂纳米晶体在具有显著光谱可调性的光子频率上转换方面很有前景。然而，上转换过程的利用受到低发光效率的限制，由于热猝灭，在高温下发光效率可能会进一步衰减。在此，我们报告了一种通用策略，通过小分子的表面配位在很宽的温度范围内提高上转换发光。机理研究证实，有机表面层钝化了缺陷并隔离了高能表面振荡器，从而防止了激发能量的耗散。随着温度升高，尤其是在潮湿环境中，能量保存效应变得更加显著。因此，配体配位后，NaGdF:Yb/Tm纳米晶体在环境温度下的上转换发射显著增强，随着温度升高至443 K，发射进一步增强。通过利用这种对热刺激的异常光学响应，我们进一步建立了用于先进防伪和逻辑加密技术的全色热致变色上转换开关。
