title: Upconversion of rare Earth nanomaterials.
abstract: Rare earth nanomaterials, which feature long-lived intermediate energy levels and intraconfigurational 4f-4f transitions, are promising supporters for photon upconversion. Owing to their unique optical properties, rare earth upconversion nanomaterials have found applications in bioimaging, theranostics, photovoltaic devices, and photochemical reactions. Here, we review recent advances in the photon upconversion processes of these nanomaterials. We start by considering energy transfer models involved in the study of upconversion emissions, as well as well-established synthesis strategies to control the size and shape of rare earth upconversion nanomaterials. Progress in engineering energy transfer pathways, which play a dominant role in determining upconversion emission outputs, is then discussed. Lastly, representative optical applications of these materials are considered. The aim of this review is to provide inspiration for researchers to explore novel upconversion nanomaterials and extended optical applications.
authors: Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, PKU-HKU Joint Laboratory in Rare Earth Materials and Bioinorganic Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China; email: sun@pku.edu.cn , yan@pku.edu.cn.
authors: Ling-Dong
authors: LD
authors: Sun
authors: Hao
authors: H
authors: Dong
authors: Pei-Zhi
authors: PZ
authors: Zhang
authors: Chun-Hua
authors: CH
authors: Yan
keywords: 4f-4f transitions; anti-Stokes emission; energy transfer; nanomaterial; optical application