RELATED APPLICATIONS

This application is a National Phase of PCT Patent Application No. PCT/CN2020/097161 having International filing date of Jun. 19, 2020, which claims the benefit of priority of Chinese Patent Application No. 202010530876.2 filed on Jun. 11, 2020. The contents of the above applications are all incorporated by reference as if fully set forth herein in their entirety.

FIELD AND BACKGROUND OF THE INVENTION

The present application relates to display panel technologies, and more particularly to an organic light-emitting device and a display device.

Organic light emitting diodes (OLEDs) have been favored by the market in recent years because they can be fabricated on flexible substrates. With the advent of foldable phones, the development of OLED can be said to have entered a second explosive stage in terms of small and medium sizes. However, in the most commonly used side-by-side system in current mobile phone display panels, a traditional blue fluorescent structure is still adopted for blue sub-pixels. The fluorescent material can only use 25% of singlet excitons such that the theoretical internal quantum efficiency is only 25%. Because only 25% of singlet excitons can be used, low efficiency and high power consumption of blue-ray devices have always been bottlenecks and obstruct the development of OLED displays.

A thermally activated delayed fluorescence (TADF) material is a new type of pure organic electronic material, which can simultaneously use singlet and triplet excitons generated by electrical excitation to achieve a theoretical internal quantum efficiency of 100%. An exciplex usually contain donor molecules and acceptor molecules. However, due to carrier imbalance propagated in the device, usually, a part of holes will get into the acceptor's highest occupied molecular orbit and a part of electrons will get into the donor's lowest unoccupied molecular orbit such that the carriers make self consistency in a monomer without forming the exciplex, thereby reducing the efficiency and stability of the devices.

Therefore, actually, there is a need to develop a new type of organic light-emitting device to overcome the drawbacks of existing arts.

SUMMARY OF THE INVENTION

The objective of the present invention is to provide an organic light-emitting device, which is capable of solving the problem of low efficiency and stability of organic light-emitting devices, caused by carrier imbalance propagated in the organic light-emitting devices in the existing arts.

To achieve above objective, the present invention provides an organic light-emitting device, including a light-emitting layer, which includes a donor light-emitting layer and an acceptor light-emitting layer, wherein at least one film layer of the donor light-emitting layer and the acceptor light-emitting layer adopts a thermally activated delayed material.

The light-emitting layer having the thermally activated delayed material may be self-luminous, and may serve as a host material doped with a guest material that emits light.

Further, in other embodiments, a thickness of the donor light-emitting layer ranges from 10 to 30 nm, a thickness of the acceptor light-emitting layer ranges from 10 to 20 nm, and the thickness of the donor light-emitting layer is greater than or equal to the thickness of the acceptor light-emitting layer. Arranging the thickness of the donor light-emitting layer510to be greater than or equal to the thickness of the acceptor light-emitting layer520can enlarge an exciton recombination area and maintain a balance between electrons and holes in the device.

Further, in other embodiments, in a case that both the donor light-emitting layer and the acceptor light-emitting layer adopt the thermally activated delayed material, a ratio of the thermally activated delayed material adopted by the donor light-emitting layer to the thermally activated delayed material adopted by the acceptor light-emitting layer ranges from 1.3:1 to 1:1.3.

In other embodiments, the donor light-emitting layer and the acceptor light-emitting layer may also be doped with a fluorescent material, and the fluorescent material may range from 1% to 10%.

Further, in other embodiments, the organic light-emitting device further includes a first exciton limiting layer, disposed at a side of the donor light-emitting layer away from the acceptor light-emitting layer; and a second exciton limiting layer, disposed at a side of the acceptor light-emitting layer away from the donor light-emitting layer.

Further, in other embodiments, the light-emitting layer includes a red light-emitting unit, a green light-emitting unit and a blue light-emitting unit, a triplet excitation energy level of both the first exciton limiting layer and the second exciton limiting layer on the red light-emitting unit is greater than or equal to 2.45 eV, a triplet excitation energy level of both the first exciton limiting layer and the second exciton limiting layer on the green light-emitting unit is greater than or equal to 2.60 eV, and a triplet excitation energy level of both the first exciton limiting layer and the second exciton limiting layer on the blue light-emitting unit is greater than or equal to 2.80 eV.

Further, in other embodiments, the organic light-emitting device further includes a hole transmission layer, disposed at a side of the light-emitting layer away from the first exciton limiting layer; a hole injection layer, disposed at a side of the hole transmission layer away from the light-emitting layer; an electron transmission layer, disposed at a side of the second exciton limiting layer away from the light-emitting layer; and an electron injection layer, disposed at a side of the electron transmission layer away from the light-emitting layer.

Further, in other embodiments, in a case that the donor light-emitting layer adopts the thermally activated delayed material and the acceptor light-emitting layer adopts no thermally activated delayed material, the acceptor light-emitting layer adopts a hole blocking material, the organic light-emitting device further includes an electron blocking layer, and the electron blocking layer is disposed between the hole transmission layer and the first exciton limiting layer.

Further, in other embodiments, a thickness of the electron blocking layer on the red light-emitting unit is greater than a thickness of the electron blocking layer on the green light-emitting unit, and a thickness of the electron blocking layer on the green light-emitting unit is greater than a thickness of the electron blocking layer on the blue light-emitting unit.

Further, in other embodiments, in a case that the acceptor light-emitting layer adopts the thermally activated delayed material and the donor light-emitting layer adopts no thermally activated delayed material, the donor light-emitting layer adopts an electron blocking material, the organic light-emitting device further includes a hole blocking layer, and the hole blocking layer is disposed between the electron transmission layer and the second exciton limiting layer.

Further, in other embodiments, in a case that both the acceptor light-emitting layer and the donor light-emitting layer adopt the thermally activated delayed material, the organic light-emitting device further includes an electron blocking layer disposed between the hole transmission layer and the first exciton limiting layer; and a hole blocking layer, disposed between the electron transmission layer and the second exciton limiting layer.

To achieve above objective, the present invention further provides a display device, which includes the organic light-emitting device involved in the present invention.

Compared to the existing arts, the beneficial effects of the present invention are described as follows. The present invention provides an organic light-emitting device and a display device, in which a donor-acceptor (D-A) structure material is chosen as the light-emitting layer, which is arranged to include the donor light-emitting layer and the acceptor light-emitting layer, at least one film layer of which adopts the thermally activated delayed material. By making use of a reverse intersystem-crossing (RISC) process of the thermally activated delayed material, making the most of injected carriers and enhancing utilization of excitons, it therefore prevents device aging and deterioration caused by excessive single-type carriers and excessive concentration of the excitons.

Further, disposing the exciton limiting layers at both sides of the light-emitting layer can prevent the energy from diffusing from the light-emitting layer to adjacent layers to cause energy loss, thereby ensuring full utilization of the energy.

