The rapid advancements in solid-state lighting have underscored the need for efficient and thermally stable phosphors for light-emitting diode (LED) applications. Herein, a red phosphor CaSc 2 O 4 :Eu 2+ ( λ ex = 450 nm, λ em = 650 nm) is synthesized employing a non-stoichiometric strategy to increase photoluminescence quantum efficiency (PLQY). Spectroscopic and crystallographic properties analysis confirm that the red emission band originates from Eu 2+ ions occupying a single Ca 2+ site with significant nephelauxetic effects and crystal field splitting. Excessive CaCO 3 additions promote the reduction of Eu 3+ and an increase of trap concentration, enhancing the PLQY from 24% to 61% and improving the emission intensities at 150 °C from 8% to 41% of that at room temperature. Versatile LED light sources, including high-quality white LED, red LED in plant growth, and the integrated pixelated intelligent LED matrices have been explored for the practical applications. This study proposes an optimized strategy to enhance the efficiency and thermal stability of Eu 2+ -doped oxide-based red phosphors for multifunctional lighting applications.
Xiaoshuai Zhang,Wen Xiong,Chengrun Liu,Zixuan Wang,Xiaoyan Yu,Xiaojie Li,Guodong Zhang,Panlai Li,Zhijun Wang
Exploring oxide-based deep red light-emitting phosphors is crucial for indoor plant lighting applications. In particular, designing Eu 2+ deep red emission in inorganic solids is challenging. In this paper, a cation substitution strategy was used to replace the Ca 2+ ions in the matrix with a certain concentration of Sr 2+ ions. A series of spectrally red-shifted Ca 1-x Sr x Sc 2 O 4 :Eu 2+ deep red phosphors were obtained under 460 nm light excitation. The substitution of Sr 2+ ions changes the local crystal field environment of Eu 2+ . The spectral shift from 656 nm to 702 nm was achieved by changing the centroid shift, the degree of polyhedral distortion and the lattice disorder. Combined with the need for practical applications, Ca 0.5 Sr 0.5 Sc 2 O 4 :0.01Eu 2+ phosphor and blue chip have been made into phosphor-converted light-emitting diodes for plant lighting, and the results of plant lighting experiments show that Ca 0.5 Sr 0.5 Sc 2 O 4 :0.01Eu 2+ phosphor has a certain application potential in plant lighting. In addition, this study will guide the exploration of new oxide-based deep red phosphors with Eu 2+ activation and for the realization of tunable emission through cation substitution.
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