A novel red-emitting phosphor Mg2Y2Al2Si2O12:Ce3+/Mn2+ for blue chip-based white LEDs |
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Authors: | Zhipeng Wang Zhijun Wang Yuebin Li Jinjin Liu Qi Bao Xiangyu Meng Keliang Qiu Zhiping Yang Dawei Wang Panlai Li |
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Affiliation: | National-Local Joint Engineering Laboratory of New Energy Photoelectric Devices, Hebei Key Laboratory of Optic-electronic Information and Materials, College of Physics Science & Technology, Hebei University, Baoding 071002 China.; Hebei Key Laboratory of Semiconductor Lighting and Display Critical Materials, Baoding 071000 China, |
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Abstract: | Traditional white light-emitting diodes (LEDs) (blue chip + YAG:Ce3+ yellow phosphor) have the limitation of red deficiency, which limits their application in the illumination field. The single cation/anion substitution or co-doping of activators can increase the red component; however, the large energy loss is attributed to the ultra-long Stokes shift and energy transfer. This work attempts to utilize the short-distance Stokes shift and a small amount of energy transfer to increase the red component in two steps. First, based on a large number of previous research results, the Mg2Y2Al2Si2O12:Ce3+ phosphor is selected. Second, additional enhancement of the red component in the emission spectrum was achieved by ion co-doping Mn2+ into Mg2Y2Al2Si2O12:Ce3+. The emission peaks for samples Mg2Y2Al2Si2O12:Ce3+,Mn2+ shift from 600 to 635 nm with increase in the concentration of Mn2+, and the emission spectra intensity of Mg1.97Y1.93Al2Si2O12:0.07 Ce3+,0.03 Mn2+ anomalously increased by ∼37%, which was attributed to the increase in the distance between Ce3+ ions because of the doping of Mn2+ ions, and reduction in the concentration of defects in the crystal, resulting in the energy loss decreases of Ce3+. The emission peak of Mg1.97Y1.93Al2Si2O12:0.07 Ce3+,0.03 Mn2+ shifts to 618 nm and the quantum efficiency was as high as 83.07%. Furthermore, this sample has high thermal stability and the emission intensity was still 80.14% at 120 °C. As such, it has great potential in the application of white LEDs.The change of the emission spectra of Mg1.93Y2-xAl2Si2O12:0.07Ce3+, xMn2+ originates from the change of the structure and the energy transfer between ions. |
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