Liu Yuan, Bai Gongxun, Lyu Yongxin, Hua Youjie, Ye Renguang, Zhang Junjie, Chen Liang, Xu Shiqing, Hao Jianhua
Institute of Optoelectronic Materials and Devices, China Jiliang University, Hangzhou 310018, People's Republic of China.
Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong, People's Republic of China.
ACS Nano. 2020 Nov 24;14(11):16003-16012. doi: 10.1021/acsnano.0c07547. Epub 2020 Nov 13.
Realizing multicolored luminescence in two-dimensional (2D) nanomaterials would afford potential for a range of next-generation nanoscale optoelectronic devices. Moreover, combining fine structured spectral line emission and detection may further enrich the studies and applications of functional nanomaterials. Herein, a lanthanide doping strategy has been utilized for the synthesis of 2D ZnSe:Er nanosheets to achieve fine-structured, multicolor luminescence spectra. Simultaneous upconversion and downconversion emission is realized, which can cover an ultrabroadband optical range, from ultraviolet through visible to the near-infrared region. By investigating the low-temperature fine structure of emission spectra at 4 K, we have observed an abundance of sublevel electronic energy transitions, elucidating the electronic structure of Er ions in the 2D ZnSe nanosheet. As the temperature is varied, these nanosheets exhibit tunable multicolored luminescence under 980 and 365 nm excitation. Utilizing the distinct sublevel transitions of Er ions, the developed 2D ZnSe:Er optical temperature sensor shows high absolute (15.23% K) and relative sensitivity (8.61% K), which is superior to conventional Er-activated upconversion luminescent nanothermometers. These findings imply that Er-doped ZnSe nanomaterials with direct and wide band gap have the potential for applications in future low-dimensional photonic and sensing devices at the 2D limit.
在二维（2D）纳米材料中实现多色发光将为一系列下一代纳米级光电器件提供潜力。此外，将精细结构的光谱线发射与检测相结合可能会进一步丰富功能纳米材料的研究和应用。在此，一种镧系元素掺杂策略已被用于合成二维ZnSe:Er纳米片，以实现具有精细结构的多色发光光谱。实现了同时上转换和下转换发射，其可以覆盖从紫外到可见光再到近红外区域的超宽带光学范围。通过研究4K下发射光谱的低温精细结构，我们观察到了大量的子能级电子能量跃迁，阐明了二维ZnSe纳米片中Er离子的电子结构。随着温度的变化，这些纳米片在980和365nm激发下表现出可调谐的多色发光。利用Er离子独特的子能级跃迁，所开发的二维ZnSe:Er光学温度传感器显示出高的绝对灵敏度（15.23%K）和相对灵敏度（8.61%K），这优于传统的Er激活上转换发光纳米温度计。这些发现表明，具有直接和宽带隙的Er掺杂ZnSe纳米材料在未来二维极限的低维光子和传感器件中具有应用潜力。
