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KR-102964352-B1 - LIGHT EMITTING DEVICE BASED ON QUANTUM DOTS INCLUDING LIGHT EMITTING LAYER BLENDED WITH HOLE TRANSPORT MATERIALS AND METHOD FOR MANUFACTURING THE SAME

KR102964352B1KR 102964352 B1KR102964352 B1KR 102964352B1KR-102964352-B1

Abstract

A quantum dot (QD)-based light-emitting device is disclosed. The light-emitting device comprises: a light-emitting layer (EML) comprising a quantum dot structure including a core and a shell, which is made of an organic polymer material having at least partially hole transport characteristics; an electron transport layer (ETL) electrically connected to one side of the light-emitting layer and configured to inject electrons into the light-emitting layer; and a hole injection layer (HIL) electrically connected to the other side of the light-emitting layer and configured to inject holes into the light-emitting layer. Meanwhile, the light-emitting device is characterized by the fact that, without a hole transport layer (HTL), a material having hole transport characteristics is mixed with quantum dots to form the light-emitting layer.

Inventors

  • 김찬수
  • 노정균
  • 이재엽
  • 이경은
  • 정진표

Assignees

  • 주식회사 모플랫
  • 부산대학교 산학협력단

Dates

Publication Date
20260513
Application Date
20241112

Claims (9)

  1. An emissive layer comprising an organic polymer material having hole transport characteristics and a quantum dot structure including a core and a shell; An electron transport layer electrically connected to one side of the light-emitting layer and configured to inject electrons into the light-emitting layer; and A hole injection layer comprising a PEDOT:PSS copolymer, configured to be electrically connected to another side of the light-emitting layer to inject holes into the light-emitting layer, wherein The organic polymer material having the above hole transport characteristics includes one or more of PVK, TFB, and Poly-TPD, and The light-emitting layer is formed by coating a mixed solution in which the organic polymer material and the quantum dot structure are dissolved in toluene onto the hole injection layer, and is in direct contact with the hole injection layer. A quantum dot-based light-emitting device that does not include a hole transport layer between the light-emitting layer and the hole injection layer.
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  3. In paragraph 1, A quantum dot-based light-emitting device in which the weight ratio of the organic polymer material to the quantum dot structure in the light-emitting layer is 1 to 30%.
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  5. A step of forming a hole injection layer comprising a PEDOT:PSS copolymer on an electrode layer made of a conductive material; A step of forming a light-emitting layer on the hole injection layer comprising an organic polymer material having hole transport characteristics and a quantum dot structure comprising a core and a shell; and The method includes the step of forming an electron transport layer on the light-emitting layer, wherein The organic polymer material having the above hole transport characteristics includes one or more of PVK, TFB, and Poly-TPD, and The step of forming the light-emitting layer above is, A step of forming a mixed solution in which the above organic polymer material is mixed with the above quantum dot structure; and The method includes the step of directly coating the mixed solution onto the hole injection layer without a hole transport layer located on the hole injection layer, and A method for manufacturing a quantum dot-based light-emitting device, comprising the step of forming the above mixed solution, which includes the step of dissolving the organic polymer material and the quantum dot structure in toluene.
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  7. In paragraph 5, A method for manufacturing a quantum dot-based light-emitting device, comprising the step of forming the above mixed solution, which includes mixing the organic polymer material with respect to the quantum dot structure in a weight ratio of 1 to 30%.
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Description

Light-emitting device based on quantum dots including a hole transport structure included in a light-emitting layer and method for manufacturing the same The embodiments relate to a quantum dot-based light-emitting device and a method for manufacturing the same. More specifically, the embodiments relate to a technology that simplifies the process and enables the realization of a large-area light-emitting device while maintaining or improving optical performance by forming a light-emissive layer (EML), in which a material having hole transport characteristics is mixed with quantum dots, directly on a hole injection layer (HIL) in a quantum dot-based light-emitting device without a hole transport layer (HTL). Quantum dot (QD) light-emitting devices are devices that utilize optical properties generated at their quantized energy levels by confining electrons and holes to dimensions smaller than the Bohr radius of excitons. In a quantum dot light-emitting device, electrons move from the cathode through the Electron Transport Layer (ETL) to the quantum dot, and holes move from the anode through the Hole Injection Layer (HIL) and the Hole Transport Layer (HTL) to the quantum dot; when electrons and holes meet in the core of the quantum dot having a core-shell structure, light is generated. Conventional quantum dot light-emitting devices employ a method of separating the electron injection layer and the transport layer to facilitate hole injection into the QD and prevent electrons from moving to the hole transport layer, thereby trapping holes and electrons in the light-emitting layer and converting them into light as much as possible. For example, Korean Patent Publication No. 10-2024-0072580 discloses a QD light-emitting device that forms a hole transport layer on the light-emitting layer and controls the size of a metal oxide to control the bandgap of the electron transport layer. When fabricating quantum dot-based light-emitting diodes (LEDs) via solution coating, the polarity, surface tension, vaporization, and orthogonality of the interface must be designed for each layer to ensure large-area uniformity. Furthermore, the properties of the thin film vary significantly depending on the surface solution wettability during the coating of each layer material. Therefore, reducing the solution coating process offers many advantages in terms of process cost and time, the realization of uniformity for each layer, and large-area processing. However, when implementing quantum dot-based LEDs according to conventional technology, it is often difficult to ensure uniformity of each layer due to increased abrasion caused by centrifugal force when manufacturing large-area devices. In particular, although it is possible to coat QDs by mixing various organic materials, there is a problem in that the organic materials that can be mixed are limited or additional methods such as cross-linking the hole transport material are required because the hole transport material also dissolves when organic materials are mixed. FIG. 1 is a cross-sectional view of a quantum dot-based light-emitting device according to one embodiment. FIG. 2 is a flowchart showing each step of a method for manufacturing a quantum dot-based light-emitting device according to one embodiment. FIG. 3 is a cross-sectional view showing the state after thin film encapsulation (TFE) of a quantum dot-based light-emitting device according to one embodiment. FIGS. 4a and 4b are diagrams showing the energy levels of each layer of a quantum dot-based light-emitting device according to one embodiment. Figure 5 is an image showing the light-emitting surface of a quantum dot-based light-emitting device formed according to the prior art. Figure 6 is an image showing the light-emitting surface of a light-emitting device in which only quantum dots are applied as the light-emitting layer without forming a hole transport layer in a quantum dot-based light-emitting device according to the prior art. FIG. 7 is an image showing the light-emitting surface of a light-emitting device in which quantum dots mixed with an organic polymer material having hole transport characteristics are applied as a light-emitting layer according to one embodiment. Figures 8a and 8b are graphs showing the electrical and optical characteristics of a quantum dot-based light-emitting device according to the embodiments compared with a device according to the prior art. Figures 9a and 9b are other graphs showing the electrical and optical characteristics of a quantum dot-based light-emitting device compared to a device according to the prior art. Hereinafter, embodiments of the present invention will be examined in detail with reference to the drawings. In describing the embodiments of this specification, if it is determined that a detailed description of known configurations or functions could obscure the essence of the embodiments of this specification, such detailed description is omitted. Additionally, par