Highly Luminescent and Photostable Quantum Dot–Silica Monolith and Its Application to Light-Emitting Diodes
2013; American Chemical Society; Volume: 7; Issue: 2 Linguagem: Inglês
10.1021/nn3052428
ISSN1936-086X
AutoresShinae Jun, Junho Lee, Eunjoo Jang,
Tópico(s)Luminescence Properties of Advanced Materials
ResumoA highly luminescent and photostable quantum dot–silica monolith (QD–SM) substance was prepared by preliminary surface exchange of the QDs and base-catalyzed sol–gel condensation of silica. The SM was heavily doped with 6-mercaptohexanol exchanged QDs up to 12 vol % (26 wt %) without particle aggregation. Propylamine catalyst was important in maintaining the original luminescence of the QDs in the SM during sol–gel condensation. The silica layer was a good barrier against oxygen and moisture, so that the QD–SM maintained its initial luminescence after high-power UV radiation (∼1 W) for 200 h and through the 150 °C LED encapsulant curing process. Green and red light-emitting QD–SMs were applied as color-converting layers on blue LEDs, and the external quantum efficiency reached up to 89% for the green QD–SM and 63% for the red one. A white LED made with a mixture of green and red QDs in the SM, in which the color coordinate was adjusted at (0.23, 0.21) in CIE1931 color space for a backlight application, showed an efficacy of 47 lm/W, the highest value yet reported.
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