Tuning the Luminescence of Phosphors: Beyond Conventional Chemical Method

Abstract

thermoluminescence (TL), and so on. [ 2 ] Nowadays, a large number of phosphors have been synthesized and developed, each one having its own characteristic emission wavelength, bandwidth, and luminescence lifetime. Here, the lifetime normally means the time in which the emission intensity decays to 1/ e . Moreover, phosphors have been extensively utilized in many areas, both scientifi c research and practical applications. For instance, phosphor-converted fl uorescent lamps and white light-emitting devices (LEDs) have been used as light sources in a widespread range of daily life and industrial applications. [ 3 ] CL and EL phosphors have been applied to traditional or modern display devices presenting visual information. [ 4 ] In the past few decades, fl uorescent nanoparticles, such as quantum dots (QDs) [ 5 ] and lanthanide (Ln) ion-doped nanocrystals, [ 6 ] have attracted considerable attention and showed great promise in fl uorescent probes, biosensing, bioimaging, therapies, and optoelectronic devices. [ 7 ] The ability to tune the luminescence properties of phosphors is highly desired in the optical materials community. [ 8 ] For various applications such as solid-state lasers, bioimaging, optical sensing, and display devices, precise control over the luminescence properties is essential for optimizing the performance and processing of optical devices and systems. Tuning luminescence is also of great signifi cance for fundamental studies of the luminescence mechanisms of phosphors. In general, tuning luminescence in the visible region is popularly known as varying the emission colour and brightness obtained by the naked eye. Broadly speaking, tuning luminescence changes the emission intensity, wavelength, bandwidth, luminescence decay or lifetime, and polarization.Numerous studies have extensively focused on tuning the luminescence of phosphors by conventional chemical ways, typically changing chemical compositions, crystal structure, phase, nanocrystal size, surface groups, and so on. [ 9 ] Comparatively, there have been less results that show the tunable luminescence of phosphors through physical methods. So far, few attempts have been made to provide a comprehensive coverage of the strategies pertaining to this emerging research fi eld and a broad overview of research advances in diverse areas of application. In this review, chemically driven luminescence tuning is Tuning the luminescence of phosphors is extremely important in controlling and processing light for active components of light sources, optical sensing, display devices, and biomedicine. So far, conventional chemical approaches have routinely been employed to modify the luminescence during the phosphor's synthesis. It is interesting to broaden the modulation of luminescence by physical methods, such as electric fi eld, magnetic fi eld, mechanical stress, temperature, photons, ionizing radiation, and so on. Since some physical methods may provide unusual routes to tune the luminescence in in-situ, real-time, dynamical and reversible mann...

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