LIGHT-EMITTING ELEMENT, LIGHT-EMITTING DEVICE, ELECTRONIC DEVICE, AND LIGHTING DEVICE

摘要

A light-emitting element including a first electrode, a second electrode, and an EL layer positioned therebetween is provided. The EL layer includes a stack of a hole-injection layer, a first layer, a second layer, a third layer, and a fourth layer; the hole-injection layer includes an organic acceptor; the first layer, the second layer and the third layer include first, second and third hole-transport materials, respectively; and the fourth layer includes a host material and a light-emitting material; the HOMO level of the second hole-transport material is deeper than that of the first hole-transport material; the HOMO level of the host material is deeper than that of the second hole-transport material; the HOMO level of the third hole-transport material is deeper than or equal to that of the host material; and a HOMO level difference between the second and third hole-transport materials is less than or equal to 0.3 eV.

主权项

1. A light-emitting element comprising:
a first electrode; a second electrode; and an EL layer, wherein the EL layer is positioned between the first electrode and the second electrode, wherein the EL layer includes a hole-injection layer, a first layer, a second layer, a third layer, and a fourth layer, wherein the hole-injection layer includes an organic acceptor, wherein the hole-injection layer is positioned between the first electrode and the first layer, wherein the second layer is positioned between the first layer and the third layer, wherein the fourth layer is positioned between the third layer and the second electrode, wherein the first layer includes a first hole-transport material, wherein the second layer includes a second hole-transport material, wherein the third layer includes a third hole-transport material, wherein the fourth layer includes a host material and a light-emitting material, wherein a HOMO level of the second hole-transport material is deeper than a HOMO level of the first hole-transport material, wherein a HOMO level of the host material is deeper than the HOMO level of the second hole-transport material, wherein a HOMO level of the third hole-transport material is deeper than or equal to the HOMO level of the host material, and wherein a difference between the HOMO level of the second hole-transport material and the HOMO level of the third hole-transport material is less than or equal to 0.3 eV.