Basic understanding of the lanthanide related upconversion emissions

Abstract

With abundant energy levels of 4f electron configurations, trivalent lanthanide ions (Ln(3+)) are endowed with unique and fascinating luminescent properties. Inheriting the native transition behaviour of the lanthanide ions, Ln(3+) based nanomaterials have aroused great interest for a wide range of applications, including lighting and displays, optical fibers and amplifiers, responsive luminescent stains for biomedical analysis, in vivo and in vitro imaging, and enhancement for silicon solar cell devices. It should be noted that the application depends completely on the corresponding luminescent behaviour. To deepen the understanding of the luminescent mechanism is important for the developing of the field and the design of new Ln(3+) based luminescent materials toward applications. In this review, we focused mainly on the recent developments on upconversion (UC) emission studies. Firstly, the emphasis was put on the introduction of basic luminescent properties of Ln(3+) with f-f transitions, and then the corresponding mechanisms and properties of UC emission were discussed in detail, the potential researches with respect to UC mechanisms and properties were finally outlined.

Li+ ions doping core–shell nanostructures: An approach to significantly enhance upconversion luminescence of lanthanide-doped nanocrystals

“…Based on the results, the proposed UC mechanism of Yb 3+ -Tm 3+ dual ions activated b-NaGdF 4 nanocrsytals is shown in Fig. 5f and briefly described as follows [40]. Firstly, the electron of Yb 3+ is excited from 2 F 7/2 to 2 F 5/2 level under the 980 nm laser excitation.…”

Advances in Rare Earth Spectroscopy and Applications

“…[22][23][24][25] It may also occur through energy transfer via host, hetero RE ions, organics, etc., phonon assisted energy transfer and cooperative processes. [26][27][28][29] UC processes can be induced by a low power (1-10 3 W cm −2 ) continuous wave laser. In contrast to a costly high-intensity (10 6 -10 9 W cm −2 pulsed laser source for the generation of a two-photon process.…”

Hydrothermal Synthesis of Novel K2YbF5:Er3+/Y3+ Microcrystals with Tunable Red–Green Upconversion Luminescence

“…4 I 15/2 ) and red emission ( 4 F 9/2 ? 4 I 15/2 ) can be clearly observed by these transitions from the aforementioned levels to 4 I 15/2 state via a two-photon UC process [42,43]. Based on the proposed UC mechanism of K 2 YbF 5 :Er 3?…”