Tandem Light-Emitting Device Intermediate Layer for Photolithography
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Solution Overview
Problem
Existing light-emitting devices with a tandem structure face challenges in achieving high resolution, low driving voltage, and high reliability, especially when manufactured using photolithography techniques that expose the EL layer to air, leading to degradation and increased driving voltage.
Innovation Solution
A light-emitting device with a tandem structure is developed, featuring an intermediate layer with a specific composition including a metal or metal oxide, a first organic compound with a π-electron deficient heteroaromatic ring and an electron-donating group, and a second organic compound with a π-electron deficient heteroaromatic ring. This configuration allows for efficient electron injection and transport, even when processed using photolithography, thereby maintaining low driving voltage and high reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography technique is used to pattern organic layers, then manufacturing precision and resolution are improved, but the EL layer is exposed to air causing deterioration and increased driving voltage
Solution Approach 1:
A protective layer is introduced as an intermediary between the EL layer and the atmosphere during photolithography processing. This protective layer prevents direct exposure of the EL layer to air, thereby maintaining its initial characteristics and reliability while allowing high-resolution patterning to proceed
Solution Approach 2:
The patent employs an inert atmosphere environment during the photolithography process to prevent oxidation and deterioration of the EL layer. By controlling the atmospheric environment, the EL layer maintains its functional properties even when exposed during patterning operations
2Manufacturing precision
If photolithography technique is used to pattern organic layers, then manufacturing precision is improved, but driving voltage increases
Solution Approach 1:
The protective layer serves as a mediator that prevents direct interaction between the EL layer and atmospheric components during photolithography. This prevents degradation of the EL layer that would otherwise increase driving voltage, while still enabling high-resolution patterning
Solution Approach 2:
The protective layer is applied before the photolithography process to preemptively protect the EL layer from air exposure. This preliminary protective action prevents the formation of degraded layers that would require higher driving voltages
3Ease of manufacture
If EL layer is exposed to air during processing, then ease of manufacture is improved, but reliability deteriorates
Solution Approach 1:
The protective layer acts as a simple intermediary that enables air processing while maintaining reliability. It allows the use of conventional photolithography techniques without requiring complex vacuum or inert atmosphere equipment, thus maintaining ease of manufacture
Solution Approach 2:
The protective layer is a temporary, disposable component that is applied for the duration of the photolithography process and then removed. This simple, temporary protection enables reliable processing without adding permanent complexity to the device structure
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 proposed light-emitting device achieves favorable characteristics such as low driving voltage and high emission efficiency, even when fabricated through a photolithography process involving exposure to air, thereby addressing the limitations of existing technologies.
Implementation Method 1
This configuration allows for efficient electron injection and transport, even when processed using photolithography, thereby maintaining low driving voltage and high reliability
Implementation Method 2
Light-emitting devices utilizing electroluminescence (hereinafter referred to as EL; such devices are also referred to as EL devices or EL elements)
Data Source
AI summary
A light-emitting device with a low driving voltage and favorable current efficiency which can be used for a high-resolution display apparatus is provided. A tandem light-emitting device that is fabricated through a photolithography process and includes a plurality of light-emitting units and an intermediate layer between the light-emitting units is provided. The intermediate layer includes a first region including a metal or a metal oxide, a first organic compound including a first π-electron deficient heteroaromatic ring with an electron-donating group, and a second organic compound including a second π-electron deficient heteroaromatic ring. The LUMO level of the second organic compound is lower than that of the first organic compound by greater than or equal to 0.30 eV.