Abstract The possibility to design and intentionally tune the luminescent properties of phosphors, e.g. their emission colour, quantum yield and kinetic behavior, is of fundamental significance and a challenge for numerous applications. Usually, to obtain multicolour emission, multiple nanomaterials with different co-dopants combinations, sizes or chemical architectures are synthesized and characterized. Of special interest would be those materials, where on-demand and in-situ modifications of multicolour emission can be obtained by changing the external stimulus, such as magnetic field, temperature, excitation intensity or pulse width. Here we synthesize and evaluate luminescent NaYF4 nanoparticles doped Yb3+/Ho3+, whose red and green emission colour is modulated by variable concentration of Ce3+ admixture, excitation pulse duration and temperature. In the first scenario (Yb3+/Ho3+ only doping), such materials exhibit strong and stable green upconversion emission. Upon Ce3+ co-doping, the red to green ratio (RGR) changed from 0,43 (for pristine dopants) to 4,23 (for 15%Ce3+ co-doped samples). Moreover, the measurement performed with excitation pulse width modulation (PWM) enabled to increase contribution of red emission in-situ. For short excitation pulses, the green emission was observed, while for longer pulses the red emission started to dominate. Finally, the energy transfer in this tri-doped system demonstrated to be susceptible to external temperature as well, with relative thermal sensitivity of 0,8%/K in biological range for 5%Ce3+ doped sample. Detailed spectroscopic analysis including temperature dependent emission spectra, rise times and emission kinetics allow us to understand and propose the possible energy transfer mechanisms in this system.

中文翻译：

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Ce3+共掺杂和激发方案对NaYF4:Yb3+,Ho3+光谱性质的影响

摘要 设计和有意调整磷光体的发光特性的可能性，例如它们的发射颜色、量子产率和动力学行为，对于许多应用具有根本意义和挑战。通常，为了获得多色发射，需要合成和表征具有不同共掺杂剂组合、尺寸或化学结构的多种纳米材料。特别感兴趣的是那些可以通过改变外部刺激（例如磁场、温度、激发强度或脉冲宽度）来按需和原位修改多色发射的材料。在这里，我们合成并评估了掺杂 Yb3+/Ho3+ 的发光 NaYF4 纳米粒子，其红色和绿色发射颜色由不同浓度的 Ce3+ 混合物调节，激励脉冲持续时间和温度。在第一种情况下（仅 Yb3+/Ho3+ 掺杂），这种材料表现出强大而稳定的绿色上转换发射。在 Ce3+ 共掺杂后，红绿比 (RGR) 从 0.43（对于原始掺杂剂）变为 4.23（对于 15%Ce3+ 共掺杂样品）。此外，使用激发脉冲宽度调制 (PWM) 进行的测量能够增加原位红色发射的贡献。对于短激发脉冲，观察到绿色发射，而对于较长脉冲，红色发射开始占主导地位。最后，该三掺杂系统中的能量转移也被证明对外部温度敏感，对于 5% Ce3+ 掺杂的样品，生物范围内的相对热灵敏度为 0.8%/K。详细的光谱分析，包括温度相关的发射光谱，