摘要 |
The invention relates to an optical light emitting diode device having an electroluminescent layer and an electron transport layer, wherein the electron transport layer contains zirconium or hafnium quinolate for slowing loss of luminance at a given current density with increase of the time for which the device has been operative. The invention also relates to OLEDs, improved efficiency and/or lifetime is obtained by using zirconium or hafnium quino late as electron transport material.
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