Morphology control, spectrum modification and extended optical applications of rare earth ion doped phosphors

Rare earth ion (RE³⁺) doped nano-phosphors with controllable morphologies have a wide range of applications in laser crystals, LEDs, bio-probes, photo-catalysis, three-dimensional displays, sensors, and flash memories. This review summarizes the morphology control strategy, phase transfer theory, spectrum modulation, and extended optical applications of RE³⁺-doped phosphors. The roles of surfactants in the morphology control in the liquid-solid-solution phase transfer process for RE³⁺-doped fluorides, oxides and other compounds are discussed. The relevant mechanisms of controlling morphologies are illustrated. The size- and shape-dependent optical properties of RE³⁺ doped phosphors, including the emission intensities, intensity ratios of adjacent emission bands, decay times and thermal stability, are analyzed. The extended optical applications and main challenges of RE³⁺-doped phosphors are also discussed.