Patent ID: 8227094

Claim:
An organic electroluminescent device for emitting blue light comprising: an anode and a cathode, and a layer which comprises an organic compound interposed between the anode and the cathode, the layer which comprises the organic compound including at least a light-emitting layer, wherein the light-emitting layer comprises a bipolar host having a hole mobility and an electron mobility of 10 −4 cm 2 /Vs or greater, a light-emitting dopant and a carrier trapping dopant; wherein the light-emitting dopant energy gap E gB , the bipolar host energy gap E gh , and the carrier trapping dopant energy gap E gd are such that E gd >E gh >E gB ; and wherein when the light-emitting dopant is a hole trapping dopant and the HOMO of the light-emitting dopant is shallower than the HOMO of the bipolar host, the carrier trapping dopant is an electron trapping dopant and the LUMO of the carrier trapping dopant is deeper than the LUMO of the bipolar host; and wherein when the light-emitting dopant is an electron trapping dopant and the LUMO of the light-emitting dopant is deeper than the LUMO of the bipolar host, the carrier trapping dopant is a hole trapping dopant and the HOMO of the carrier trapping dopant is shallower than the HOMO of the bipolar host.