All-inorganic CsPbX₃ (X = Cl, Br, and I) perovskite quantum dots (PeQDs) have gained intensive attentions due to their excellent linear properties and promising applications in optoelectronics and photovoltaics. However, due to the limitation of nonlinear upconversion, the multiphoton absorption efficiency in PeQDs is very low. Here, we present the near-infrared-pumped upconversion (UC) luminescence of CsPbI₃ PeQDs sensitized by CaF₂:Yb³⁺/Ho³⁺ hierarchical nanospheres (HNSs) in the CsPbI₃ and CaF₂:Yb³⁺/Ho³⁺ nanocomposite structure. By introducing appropriate proportion of Br⁻ ions, UC luminescence can be easily tuned from 695 nm to 655 nm. The lifetimes of CsPbI₃ PeQDs excitonic emissions are lengthened to several milliseconds during the energy transfer process from the long-lived Ho³⁺ to CsPbI₃ PeQDs, which can be tuned by changing the Br/I ratio. The stability of CsPbI₃ PeQDs is enhanced in the composites, which keeps 90 % photo luminescence after 30 days. The composites are printed on the flexible substrate for dual-mode fluorescent encryption anti-counterfeiting application, which display excellent fluorescence under the excitation of both ultraviolet and near-infrared light. Moreover, the CsPbI₃ and CaF₂:Yb³⁺/Ho³⁺ nanocomposites are highly water-soluble, which demonstrate ultrastability and high biocompatibility in the cell imaging application. This work provides a new strategy to develop photon upconversion in PeQDs, and blazes a new trail for the development of multifunctional materials.

全无机 CsPbX ₃ (X = Cl、Br 和 I) 钙钛矿量子点 (PeQDs) 由于其优异的线性特性和在光电子学和光伏领域的应用前景而受到广泛关注。然而，由于非线性上转换的限制，PeQDs 中的多光子吸收效率非常低。在这里，我们展示了CsPbI ₃和 CaF ₂ :Yb ³⁺ /Ho ^{3 中}由 CaF ₂ :Yb ³⁺ /Ho ³⁺分级纳米球 (HNSs)敏化的 CsPbI ₃ PeQD的近红外泵浦上转换 (UC) 发光⁺纳米复合结构。通过引入适当比例的 Br ^-离子，UC 发光可以很容易地从 695 nm 调谐到 655 nm。在从长寿命的 Ho ³⁺到 CsPbI ₃ PeQDs的能量转移过程中，CsPbI ₃ PeQDs 激子发射的寿命延长到几毫秒，这可以通过改变 Br/I 比来调整。CsPbI ₃ PeQDs的稳定性在复合材料中得到增强，在 30 天后保持 90% 的光致发光。复合材料印刷在柔性基板上，用于双模荧光加密防伪应用，在紫外光和近红外光的激发下显示出优异的荧光。此外，CsPbI ₃和 CaF ₂ :Yb ³⁺ /Ho³⁺纳米复合材料具有高度水溶性，在细胞成像应用中表现出超稳定性和高生物相容性。这项工作为开发PeQDs中的光子上转换提供了新的策略，并为多功能材料的开发开辟了新的道路。