Chemical Science and Engineering Division, Argonne National Laboratory, Argonne, IL 60439, USA.
Chem Soc Rev. 2015 Mar 21;44(6):1635-52. doi: 10.1039/c4cs00187g.
Photon upconversion in rare earth activated phosphors involves multiple mechanisms of electronic transitions. Stepwise optical excitation, energy transfer, and various nonlinear and collective light-matter interaction processes act together to convert low-energy photons into short-wavelength light emission. Upconversion luminescence from nanomaterials exhibits additional size and surface dependencies. A fundamental understanding of the overall performance of an upconversion system requires basic theories on the spectroscopic properties of solids containing rare earth ions. This review article surveys the recent progress in the theoretical interpretations of the spectroscopic characteristics and luminescence dynamics of photon upconversion in rare earth activated phosphors. The primary aspects of upconversion processes, including energy level splitting, transition probability, line broadening, non-radiative relaxation and energy transfer, are covered with an emphasis on interpreting experimental observations. Theoretical models and methods for analyzing nano-phenomena in upconversion are introduced with detailed discussions on recently reported experimental results.
稀土激活荧光粉中的光子上转换涉及多种电子跃迁机制。逐步光激发、能量转移以及各种非线性和集体光物质相互作用过程共同作用，将低能量光子转换为短波长光发射。纳米材料的上转换发光表现出额外的尺寸和表面依赖性。要全面了解上转换系统的整体性能，就需要对包含稀土离子的固体的光谱特性的基本理论有所了解。本文综述了近年来在解释稀土激活荧光粉中光子上转换的光谱特性和发光动力学方面的理论解释方面的进展。涵盖了上转换过程的主要方面，包括能级分裂、跃迁概率、谱线展宽、非辐射弛豫和能量转移，重点解释了实验观察结果。介绍了分析上转换中纳米现象的理论模型和方法，并详细讨论了最近报道的实验结果。
