Lanthanide-doped upconversion nanoparticles (UCNPs) are capable of converting near-infra-red excitation into visible and ultraviolet emission. Their unique optical properties have advanced a broad range of applications, such as fluorescent microscopy, deep-tissue bioimaging, nanomedicine, optogenetics, security labelling and volumetric display. However, the constraint of concentration quenching on upconversion luminescence has hampered the nanoscience community to develop bright UCNPs with a large number of dopants. This review surveys recent advances in developing highly doped UCNPs, highlights the strategies that bypass the concentration quenching effect, and discusses new optical properties as well as emerging applications enabled by these nanoparticles.

中文翻译：

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高掺杂上转换纳米粒子的研究进展。

掺杂镧系元素的上转换纳米粒子（UCNP）能够将近红外激发转换为可见光和紫外线发射。它们独特的光学特性已推动了广泛的应用，例如荧光显微镜，深层生物成像，纳米药物，光遗传学，安全标记和体积显示。然而，浓度猝灭对上转换发光的约束已经阻碍了纳米科学界开发具有大量掺杂剂的明亮的UCNP。这篇综述调查了开发高掺杂UCNPs的最新进展，重点介绍了绕过浓度猝灭效应的策略，并讨论了这些纳米颗粒带来的新的光学性质以及新兴应用。