研究目的
To develop novel efficient Ce3+/Tb3+ co-doped Ca2GdZr2Al3O12 (CGZA) green-emitting phosphors for near-UV-pumped high-CRI warm-white LEDs.
研究成果
The CGZA:Ce3+,Tb3+ phosphors exhibited an intense and broad excitation band in range of 370-470 nm centering at 408 nm, which matched well with near-UV-emitting LED chips. The Ce3+→Tb3+ ET efficiency in CGZA:0.02Ce3+,xTb3+ phosphors reached 79.2% when x = 0.9. Under 408 nm excitation, CGZA:Ce3+,Tb3+ phosphors generated bright green emissions of Tb3+ ions as a result of efficient Ce3+→Tb3+ ET. The ET mechanism in CGZA:Ce3+,Tb3+ was investigated to result in a dipole-dipole interaction. The optimal sample CGZA:0.02Ce3+,0.8Tb3+ had a high IQE value of 51%. A warm-white LED lamp was successfully fabricated and exhibited a much higher CRI (Ra = 91.2) than traditional white LEDs based on the combination of blue chips with YAG:Ce3+ yellow phosphors (Ra = 74.8).
研究不足
The presence of ZrO2 impurity due to its ultrahigh melting point of 2700 °C.