Graphene Oxide Hole Injection Layer for OLED Anode Work Function
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Solution Overview
Problem
The low work function of Indium Tin Oxide (ITO) in OLED display devices limits hole injection and transport capabilities, adversely affecting light emitting performance due to a hole injection barrier that is not adequately reduced by existing physical treatments.
Innovation Solution
A graphene oxide layer is formed over the anode layer using an electroplating process, which can function as a hole injection or transport layer, reducing the hole injection barrier and enhancing hole injection and transport capabilities, thereby improving light emitting performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ITO material is used as anode layer, then stable chemical properties and high conductivity are achieved, but low work function reduces hole injection and transport capability
Solution Approach 1:
A hole injection layer with high HOMO level is introduced as an intermediary between the ITO anode and the hole transport layer. This intermediary layer has high conductivity and high HOMO level, which enables effective hole injection from ITO while maintaining chemical stability. The hole injection layer acts as a bridge that resolves the mismatch between ITO's low work function and the requirements for efficient hole injection.
2Reliability
If physical treatments such as oxygen plasma or UV radiation are applied to ITO, then work function is increased, but it is still difficult to reach 5.0 eV required for adequate hole injection
Solution Approach 1:
Instead of relying on physical treatments to modify ITO's work function, the invention changes the material parameter by introducing a hole injection layer with inherently high HOMO level. This layer provides the necessary energy level alignment for efficient hole injection without requiring complex physical treatment processes, thus maintaining manufacturing simplicity while achieving the desired electrical properties.
3Object-generated harmful factors
If hole injection layer and hole transport layer are added to improve hole transport, then hole injection capability is enhanced, but device structure becomes more complex
Solution Approach 1:
The hole injection layer is designed with multi-functionality: it provides high HOMO level for efficient hole injection, maintains high conductivity for effective charge transport, and offers chemical stability. By consolidating multiple functions into a single strategically positioned layer, the device achieves improved hole injection and transport capabilities without proportionally increasing structural complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The graphene oxide layer, with its high work function, improves the energy level matching at the anode layer interface, leading to enhanced hole-injection and hole-transport capabilities, thus improving the light emitting efficiency of OLED display devices.
Implementation Method 1
A graphene oxide layer is formed over the pattern of the anode layer by an electroplating process
Implementation Method 2
A voltage is applied between the cathode and the anode layer on the base substrate to deposit the graphene oxide layer over the pattern of the anode layer
Data Source
AI summary
The present disclosure provides an organic light-emitting diode (OLED) display device, a manufacturing method thereof, and a display apparatus containing the OLED display device. A pattern of an anode layer is formed over a base substrate. A graphene oxide layer is formed over the pattern of the anode layer by an electroplating process. The graphene oxide layer is used as an auxiliary layer or is used as at least one of a hole injection layer and a hole transport layer in the OLED display device. Since the graphene oxide material has high work function, the hole injection barrier may be reduced and to the hole injection and hole transport capability of the OLED display device may be enhanced to improve light emitting performance of the OLED display device.