Recent Research Progress of Long-wavelength Emitting Long-persistent Luminescence Materials
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Recent Research Progress of Long-wavelength Emitting Long-persistent Luminescence Materials Wei Zeng1, Yuhua Wang1*, Yanqin Li1 and Xuhui Xu1 Department of Materials Science, School of Physical Science and Technology, Lanzhou University, 730000, PR China.
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Abstract Blue and Green long-persistent luminescence materials have been fully developed, and are well featured in production and application. However, long-wavelength emitting materials are very rare relatively. This paper presents some work from our laboratory on the recent progress in long-wavelength emitting long-persistent luminescence materials: Sr3Al2O5Cl2: Eu2+, Tm3+, Sr2SnO4: Sm3+ and Ca2BO3Cl: Eu2+, Dy3+. The initial intensity of Sr3Al2O5Cl2: Eu2+, Tm3+ can reach nearly 5000 mcd/m2 and its afterglow can last about 220 min at recognizable intensity level. Sr2SnO4: Sm3+ has a red emission and its afterglow time of which sintered in vacuum atmosphere increased substantially. With optimum doping concentration and sufficient excitation with UV light, the yellow afterglow of Ca2BO3Cl: Eu2+, Dy3+ can persist over 48 h. 1.
Introduction Long-persistent luminescence (LPL) materials have attracted considerable attention for various displays and signing applications as environmentally friendly and energy efficient materials.[1-5] LPL materials have been widely used in many areas such as emergent lighting device, display, multidimensional optical memory and imaging storage. In recently, more and more fields such as solar energy utilization and in vivo bio-imaging can use LPL materials to solve relevant questions.[6-7] Taking bio-imaging as an example, the utilization of LPL materials will result in the advantages of circumventing autofluorescence from animal tissues, improving the signal to noise ratio. In theory, we can get any color by mixing the three primary colors with different proportions. However, this method is hard to actualize because of the following reasons. Until now, two of the tricolor long-persistent phosphors, green (SrAl2O4: Eu2+, Dy3+, > 24 h) and blue (CaAl2O4: Eu2+, Nd3+, > 24 h), are commercially available.[8-9] But the afterglow decay time of the best red long-persistent phosphor (Y2O2S: Eu3+, Mg2+, Ti4+) reported by now, is only 5 hours.[10] On the other hand, the decay process is hardly to be guaranteed consistency for different components, which scarcely ensure the uniformity of phosphorescence color. In addition, most of the long-persistent phosphors cannot be efficiently excited by the same excitation source. Therefore, it’s essential to investigate and develop novel multicolored long-persistent phosphors. However, a large number of novel LPL materials based on different hosts have been reported in the literature. Most of them are green or blue.[11-12]
Long-wavelength emitting LPL materials (≥570 nm) are uncommon.[13-15] Thus there is an increasing demand for long-wavelength emitting LPL materials. This paper shows some work from our laboratory on recent progress in long-wavelength emitting LPL materials. 2.
Results and discussion
