Patent ID: 7906900

Claim:
A white OLED (organic light emitting device) comprising: an anode; a cathode spaced apart from the anode; a blue light emitting layer formed between the anode and the cathode; a green light emitting layer formed between the blue light emitting layer and the cathode; a red light emitting layer formed between the green light emitting layer and the cathode; a first buffer layer formed between the blue light emitting layer and the green light emitting layer, the first buffer layer having a HOMO (highest occupied molecular orbital)−LOMO (lowest occupied molecular orbital) energy gap higher than or equal to a HOMO−LOMO energy gap of the blue light emitting layer and the green light emitting layer, the first buffer layer having both hole transport characteristics and electron transport characteristics higher than the hole transport characteristics; and a second buffer layer formed between the green light emitting layer and the red light emitting layer, the second buffer layer having a LOMO energy level higher than a LOMO energy level of the red light emitting layer, the second buffer layer having hole transport characteristics and reducing the quantity of the electrons to be transported from the red light emitting layer to the green light emitting layer.