Double-Side OLED With Composite Anode and Cathode
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Solution Overview
Problem
Conventional double-emitting organic light emitting diodes have poor cathode resistance and contact with the periphery circuit, leading to short lifetime and low transmittance, typically around 50%.
Innovation Solution
A diode structure comprising a composite anode, a transparent metal oxide layer, and a composite cathode with specific layer configurations and materials, including a thin first transparent metal layer, a basic stack layer, and two second transparent metal layers, along with an anti-reflective and barrier layer to enhance energy level matching and microcavity effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the cathode is made very thin to achieve better transmittance, then the transmittance is improved, but the cathode resistance becomes too high and contact with periphery circuit is poor
Solution Approach 1:
The cathode is divided into multiple layers: a first transparent metal layer (5-10 nm) for transmittance, a transparent metal oxide layer (1-5 nm) for energy level matching, and a second transparent metal layer for electrical contact. This segmentation allows each layer to optimize for its specific function, resolving the contradiction between transmittance and electrical contact reliability.
Solution Approach 2:
The cathode uses composite material structure combining transparent metal (e.g., aluminum, silver), transparent metal oxide (e.g., ITO, IZO), and organic materials. This composite structure achieves both high transmittance and low resistance by combining materials with complementary properties.
2Illumination intensity
If the cathode is made very thin to achieve better transmittance, then the transmittance is improved, but the lifetime becomes short
Solution Approach 1:
The transparent metal oxide layer is inserted beforehand to provide energy level matching and protect the interface between the transparent metal layer and the electron transport layer. This prevents degradation and extends device lifetime while maintaining high transmittance.
Solution Approach 2:
The multi-layer composite cathode structure with transparent metal oxide and organic layers provides both high transmittance and improved stability, extending device lifetime compared to conventional single-layer thin cathodes.
3Device complexity
If a single-layered transparent anode and cathode are used, then the structure is simple, but the energy level matching is poor and efficiency is low
Solution Approach 1:
The anode is segmented into transparent anode layer (ITO) and first transparent metal layer (Al, Ag), while the cathode is segmented into transparent metal layer, transparent metal oxide layer, and organic layer. This segmentation enables better energy level matching and improved device efficiency.
Solution Approach 2:
The work function of the anode is adjusted by adding transparent metal layer (5-10 nm) to match the HOMO level of the hole transport layer. The electron transport layer's LUMO level is matched with the transparent metal oxide layer's work function (difference 0-1 eV). These parameter optimizations significantly improve device efficiency.
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
Significantly improves transmittance, efficiency, and reliability, extending the diode's lifetime and enhancing brightness, with improved energy level matching and the use of mirror and microcavity effects.
Implementation Method 1
a difference between a work function of a material making the transparent metal oxide layer and a highest occupied molecular orbital value of a material used for making the electron inject layer of the diode is between 0 eV and 1 eV
Implementation Method 2
with the help of mirror effect and microcavity effect, both efficiency and brightness of the diode from the substrate surface are much more improved
Implementation Method 3
with the help of mirror effect and microcavity effect, both efficiency and brightness of the diode from the substrate surface are much more improved
Implementation Method 4
the diode further comprises an anti-reflective layer, and the anti-reflective layer is formed on the non-transparent metal layer
Data Source
AI summary
The present invention discloses a diode and a manufacturing method thereof and a display apparatus. The diode comprises a composite anode, a transparent metal oxide layer, a basic stack layer, and a composite cathode. The composite anode comprises a transparent anode layer and a first transparent metal layer. The first transparent metal layer is formed on the transparent anode layer. The transparent metal oxide layer is formed on the first transparent metal layer. The basic stack layer is formed on the transparent metal oxide layer. The composite cathode comprises two second transparent metal layers. The two second transparent metal layers are formed on the basic stack layer. Both transmittance and efficiency of the diode are significantly improved. The reliability of the diode is improved to elongate the lifetime of the diode.