The structure and optical characteristics of white-light nano-phosphors applied to LEDs

• The YAP:Dy phosphor can emit white light without complementary phosphors.
• The energy level diagram of Dy3 + ion can explain the formation of emissions.
• The optimal Dy3 + concentration in the YAP phosphor is found.

The white-light phosphors consisting of dysprosium doped yttrium aluminate were synthesized by the chemical co-precipitation method with the suitable thermal treatments. After one-hour thermal treatment in the air atmosphere, the white-light phosphor with particle size around 120 nm can be obtained. The XRD patterns reveal that the aluminate-based phosphors are the mixtures of YAlO3 (YAP) and Y4Al2O9 (YAM). From the PLE spectra, five absorption peaks locating at 294, 325, 352, 363 and 387 nm can be observed. These peaks appear due to the following electron transitions, 6H15/2 → 4K13/2, 6H15/2 → 4K16/2, 6H15/2 → 4M15/2 + 6P7/2, 6H15/2 → 4I11/2 and 6H15/2 → 6M19/2, respectively. Additionally, two emission peaks locating at 484 nm (blue-light) and 576 nm (yellow-light) can be observed in the PL spectra and they originate from the electron transitions, 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2. The optimal PL intensity of YAlO3 phosphors can be obtained with 1% dysprosium ions. When the concentration of Dy3 + ions increases to 1.2%, the concentration quenching effect is observed. According to the CIE diagram, the coordinates of YAlO3:Dy3 + phosphors locate within the white-light area.

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