Patent ID: 9666825
Date: 2017-05-30
CPC Classifications: H01L

Claim:
1. A light-emitting device comprising: a first electrode; a first light-emitting layer over the first electrode; a second light-emitting layer over and in direct contact with the first light-emitting layer; a third light-emitting layer over and in direct contact with the second light-emitting layer; and a second electrode over the third light-emitting layer, wherein: the first light-emitting layer comprises a first light-emitting material, a first hole-transport material, and a first electron-transport material, the second light-emitting layer comprises a second light-emitting material, a second hole-transport material, and a second electron-transport material, the third light-emitting layer comprises a third light-emitting material, a third hole-transport material, and a third electron-transport material, a first weight proportion of the first hole-transport material to the first electron-transport material in the first light-emitting layer is lower than or equal to 50%, a second weight proportion of the third hole-transport material to the third electron-transport material in the third light-emitting layer is lower than or equal to 50%, a third weight proportion of the second hole-transport material to the second electron-transport material in the second light-emitting layer is lower than or equal to the first weight proportion and the second weight proportion, the first light-emitting layer and the third light-emitting layer exhibit first emission, and second emission from the second light-emitting layer has an emission peak at a longer wavelength than the first emission.