Photon upconversion of lanthanides has been a powerful means to convert low-energy photons into high-energy ones. However, in contrast to the mostly investigated lanthanide ions, it has remained a challenge for the efficient upconversion of Nd³⁺ due to the deleterious concentration quenching effect. Here we report an efficient strategy to enhance the upconversion of Nd³⁺ through the Yb³⁺-mediated energy cycling in a core-shell-shell nanostructure. Both Nd³⁺ and Yb³⁺ are confined in the interlayer, and the presence of Yb³⁺ in the Nd-sublattice provides a more matched energy for the upconversion transitions occurring at the intermediate state of Nd³⁺ towards much better population at its emissive levels. Moreover, this design also minimizes the possible cross-relaxation processes at both intermediate level and the emissive levels of Nd³⁺ which are the primary factors limiting the upconversion performance for the Nd³⁺-doped materials. Such energy cycling-enhanced upconversion shows promise in temperature sensing.

镧系元素的光子上转换一直是将低能光子转换为高能光子的有力手段。然而，与大多数研究的镧系元素离子相比，由于有害的浓度猝灭效应，Nd ³⁺的有效上转换仍然是一个挑战。在这里，我们报告了一种通过核-壳-壳纳米结构中Yb ³⁺介导的能量循环来增强 Nd ³⁺上转换的有效策略。Nd ³⁺和 Yb ³⁺都被限制在中间层中，并且Nd 亚晶格中 Yb ³⁺的存在为发生在 Nd ³⁺中间态的上转换跃迁提供了更匹配的能量在其排放水平上实现更好的人口。此外，这种设计还最大限度地减少了中间能级和 Nd ³⁺发射能级的可能交叉弛豫过程，这是限制 Nd ³⁺掺杂材料上转换性能的主要因素。这种能量循环增强的上转换在温度传感中显示出前景。