| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a light-emitting element with high external quantum efficiency. <P>SOLUTION: A light-emitting layer 102 including a guest, an N-type host, and a P-type host is provided between a pair of electrodes. A first layer (N-type host layer 103) is formed between the light-emitting layer 102 and a negative electrode, and a second layer (P-type host layer 104) is formed between the light-emitting layer 102 and a positive electrode. No energy barrier exists when electrons or holes are injected to the light-emitting layer 102. Meanwhile, an energy barrier exists on the way when the electrons move to the positive electrode or the holes move to the negative electrode, so that the electrons and holes are confined in the light-emitting layer. Thus, the energy use efficiency is increased. Regions where the concentrations of the N-type host and the P-type host continuously change may be provided between the N-type host layer 103 and the light-emitting layer 102 or between the P-type host layer 104 and the light-emitting layer 102. <P>COPYRIGHT: (C)2013,JPO&INPIT |
