US-12622131-B2 - Organic electroluminescent device, display panel, and display apparatus

US12622131B2US 12622131 B2US12622131 B2US 12622131B2US-12622131-B2

Abstract

Provided are an organic electroluminescent device, a display panel, and a display apparatus. An exciton layer adjacent to a light-emitting layer is added, and the exciton layer serves as an exciton recombination region and achieves the effect of increasing the density of excitons, where the singlet-state energy level of the exciton layer is higher than the singlet-state energy level of a host material in the light-emitting layer, and an emission spectrum of the exciton layer and an absorption spectrum of the host material in the light-emitting layer have an overlapping area. Moreover, the exciton layer allows triplet-state excitons formed in the exciton layer to form singlet-state excitons via a reverse intersystem crossing process.

Inventors

Yong Wu

Assignees

BOE TECHNOLOGY GROUP CO., LTD.

Dates

Publication Date: 20260505
Application Date: 20210804
Priority Date: 20200923

Claims (14)

1 . An organic electroluminescent device, comprising: an anode and a cathode, arranged in opposite; a light-emitting layer, between the anode and the cathode; and an exciton layer, adjacent to the light-emitting layer, wherein the exciton layer, the light-emitting layer, the anode and the cathode are arranged in a stacked manner; wherein the exciton layer allows triplet-state excitons formed in the exciton layer to form singlet-state excitons via a reverse intersystem crossing process; a singlet-state energy level of the exciton layer is higher than a singlet-state energy level of a host material in the light-emitting layer, and an overlap ratio between an emission spectrum of the exciton layer and an absorption spectrum of the host material in the light-emitting layer is greater than a set value; wherein the exciton layer consists of one compound; and the compound has a characteristic of emitting thermally activated delayed fluorescence.
2 . The organic electroluminescent device according to claim 1 , wherein the overlap ratio between the emission spectrum of the exciton layer and the absorption spectrum of the host material in the light-emitting layer is greater than 5%.
3 . The organic electroluminescent device according to claim 1 , wherein an electron mobility of the host material in the light-emitting layer is greater than a hole mobility of the host material in the light-emitting layer, and the exciton layer is disposed on a side of the light-emitting layer facing the anode; or the electron mobility of the host material in the light-emitting layer is smaller than the hole mobility of the host material in the light-emitting layer, and the exciton layer is disposed on a side of the light-emitting layer facing the cathode.
4 . The organic electroluminescent device according to claim 3 , further comprising: at least one auxiliary function layer disposed on a side of the exciton layer facing away from the light-emitting layer; wherein the singlet-state energy level of the exciton layer is smaller than a singlet-state energy level of an adjacent auxiliary function layer of the at least one auxiliary function layer.
5 . The organic electroluminescent device according to claim 1 , further comprising: at least one auxiliary function layer disposed on a side of the exciton layer facing away from the light-emitting layer; wherein an Lowest Unoccupied Molecular Orbital, LUMO, value of the at least one compound in the exciton layer is greater than an LUMO value of an adjacent auxiliary function layer of the at least one auxiliary function layer.
6 . The organic electroluminescent device according to claim 5 , wherein an absolute value of a difference between the LUMO value of the at least one compound in the exciton layer and the LUMO value of the adjacent auxiliary function layer is greater than 0.3 eV; and an absolute value of a difference between an Highest Occupied Molecular Orbital, HOMO, value of the at least one compound in the exciton layer and an HOMO value of the adjacent auxiliary function layer is smaller than 0.5 eV.
7 . The organic electroluminescent device according to claim 4 , wherein when the exciton layer is disposed on the side of the light-emitting layer facing the anode, the at least one auxiliary function layer comprises at least one of following: a hole injection layer, a hole transport layer or an electron blocking layer; or when the exciton layer is disposed on the side of the light-emitting layer facing the cathode, the at least one auxiliary function layer comprises at least one of following: an electron injection layer, an electron transport layer or a hole blocking layer.
8 . The organic electroluminescent device according to claim 1 , wherein a thickness of the exciton layer is smaller than or equal to 20 nm.
9 . A display panel, comprising a plurality of organic electroluminescent devices, wherein each of the plurality of organic electroluminescent devices is according to claim 1 .
10 . A display apparatus, comprising: the display panel according to claim 9 .
11 . The organic electroluminescent device according to claim 5 , wherein when the exciton layer is disposed on the side of the light-emitting layer facing the anode, the at least one auxiliary function layer comprises at least one of following: a hole injection layer, a hole transport layer or an electron blocking layer; or when the exciton layer is disposed on the side of the light-emitting layer facing the cathode, the at least one auxiliary function layer comprises at least one of following: an electron injection layer, an electron transport layer or a hole blocking layer.
12 . The display panel according to claim 9 , wherein the overlap ratio between the emission spectrum of the exciton layer and the absorption spectrum of the host material in the light-emitting layer is greater than 5%.
13 . The display panel according to claim 9 , wherein an electron mobility of the host material in the light-emitting layer is greater than a hole mobility of the host material in the light-emitting layer, and the exciton layer is disposed on a side of the light-emitting layer facing the anode; or the electron mobility of the host material in the light-emitting layer is smaller than the hole mobility of the host material in the light-emitting layer, and the exciton layer is disposed on a side of the light-emitting layer facing the cathode.
14 . The display panel according to claim 13 , the organic electroluminescent device further comprising: at least one auxiliary function layer disposed on a side of the exciton layer facing away from the light-emitting layer; wherein the singlet-state energy level of the exciton layer is smaller than a singlet-state energy level of an adjacent auxiliary function layer of the at least one auxiliary function layer.

Description

CROSS REFERENCE TO RELATED APPLICATIONS The present disclosure is a National Stage of International Application No. PCT/CN2021/110673, filed Aug. 4, 2021, which claims priority to the Chinese Patent Application No. 202011012901.4, entitled “ORGANIC ELECTROLUMINESCENT DEVICE, DISPLAY PANEL, AND DISPLAY APPARATUS”, and filed to the China National Intellectual Property Administration on Sep. 23, 2020, the entire contents of which are incorporated herein by reference. FIELD The present disclosure relates to the technical field of display, in particular to an organic electroluminescent device, a display panel and a display apparatus. BACKGROUND In recent years, an organic light-emitting display (OLED), as a new type of flat panel display, has attracted more and more attention. Because of features including active lighting, high brightness, high resolution, wide viewing angle, fast response, color saturation, lightness and thinness, low energy consumption, flexibility and the like, it is known as a dream display, and has become a hot mainstream display product in the market. SUMMARY In an aspect, an embodiment of the present disclosure provides an organic electroluminescent device, including: an anode and a cathode, arranged in opposite;a light-emitting layer, between the anode and the cathode; andan exciton layer adjacent to the light-emitting layer in a direction pointing from the anode to the cathode; wherethe exciton layer includes at least one compound, the exciton layer allows triplet-state excitons formed in the exciton layer to form singlet-state excitons via a reverse intersystem crossing, a singlet-state energy level of the exciton layer is higher than a singlet-state energy level of a host material in the light-emitting layer, and an overlap ratio between an emission spectrum of the exciton layer and an absorption spectrum of the host material in the light-emitting layer is greater than a set value. In some embodiments, the overlap ratio between the emission spectrum of the exciton layer and the absorption spectrum of the host material in the light-emitting layer is greater than 5%. In some embodiments, the exciton layer includes one compound, and the compound has a characteristic of emitting thermally activated delayed fluorescence. In some embodiments, the exciton layer includes an exciplex formed by mixing a first compound and a second compound, and an exciton yield of the exciplex is greater than 50%. In some embodiments, a mass ratio of the first compound to the second compound ranges from 1:9 to 9:1. In some embodiments, an electron mobility of the host material in the light-emitting layer is greater than a hole mobility of the host material in the light-emitting layer, and the exciton layer is disposed on a side of the light-emitting layer facing the anode; or the electron mobility of the host material in the light-emitting layer is smaller than the hole mobility of the host material in the light-emitting layer, and the exciton layer is disposed on a side of the light-emitting layer facing the cathode. In some embodiments, the organic electroluminescent device further includes: at least one auxiliary function layer disposed on a side of the exciton layer facing away from the light-emitting layer; and the singlet-state energy level of the exciton layer is smaller than a singlet-state energy level of an adjacent auxiliary function layer of the at least one auxiliary function layer. In some embodiments, the organic electroluminescent device further includes: at least one auxiliary function layer disposed on a side of the exciton layer facing away from the light-emitting layer; and an Lowest Unoccupied Molecular Orbital, LUMO, value of the at least one compound in the exciton layer is greater than an LUMO value of an adjacent auxiliary function layer of the at least one auxiliary function layer. In some embodiments, an absolute value of a difference between the LUMO value of the at least one compound in the exciton layer and the LUMO value of the adjacent auxiliary function layer is greater than 0.3 eV; and an absolute value of a difference between an Highest Occupied Molecular Orbital, HOMO, value of the at least one compound in the exciton layer and an HOMO value of the adjacent auxiliary function layer is smaller than 0.5 eV. In some embodiments, when the exciton layer is disposed on the side of the light-emitting layer facing the anode, the at least one auxiliary function layer includes at least one of following: a hole injection layer, a hole transport layer or an electron blocking layer; or when the exciton layer is disposed on the side of the light-emitting layer facing the cathode, the at least one auxiliary function layer includes at least one of following: an electron injection layer, an electron transport layer or a hole blocking layer. In some embodiments, a thickness of the exciton layer is smaller than or equal to 20 nm. In another aspect, an embodiment of the present disclosure furthe