Organic EL Display Connecting Layer for Abnormal Light Color
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Solution Overview
Problem
Conventional organic electroluminescent display devices face issues with abnormal light color and poor luminescent efficiency due to the heterogeneous interfaces formed during the transition between solution and vacuum thermal evaporation processes, affecting carrier recombination and light emission.
Innovation Solution
An organic electroluminescent display device with a stack of first and second light emitting sub-layers, where a connecting layer formed by an electron-transporting material is placed between them, ensuring partial or complete overlap of the connecting layer's pattern with the first light emitting sub-layer on the base substrate, facilitating separate carrier recombination regions and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If solution process and vacuum thermal evaporation process are co-used to produce the organic electroluminescent display device, then the device can be manufactured with multiple light emitting materials, but the heterogeneous interface properties are affected causing abnormal light color
Solution Approach 1:
The patent introduces a connecting layer made of electron-transporting material between the first light emitting sub-layer (produced by solution process) and the second light emitting sub-layer (produced by vacuum thermal evaporation process). This connecting layer acts as an intermediary that bridges the heterogeneous interface, ensuring smooth transition of charge carriers and maintaining uniform interface properties, thereby preventing abnormal light color while preserving the ability to use multiple light emitting materials from different processes.
2Ease of manufacture
If conventional co-process manufacturing is used, then production flexibility is maintained, but luminescent efficiency is poor due to carrier recombination issues at heterogeneous interfaces
Solution Approach 1:
The connecting layer serves as a mediator that facilitates efficient carrier recombination at the interface between solution-process and vacuum-evaporation layers. By providing a dedicated electron-transporting pathway, it ensures that electrons and holes recombine efficiently within the light emitting layers, significantly improving luminescent efficiency while maintaining the flexibility to use different manufacturing processes for different sub-layers.
3Ease of manufacture
If the connecting layer pattern does not overlap with the first light emitting sub-layer, then manufacturing is simpler, but carrier recombination is affected causing abnormal light color
Solution Approach 1:
The patent applies local quality by making the connecting layer's projection area overlap with the projection area of the first light emitting sub-layer. This localized overlap ensures that electron transport and carrier recombination occur precisely where needed - in the region where the first light emitting sub-layer is present - thereby maintaining accurate light color reproduction. The overlapping configuration is applied only where necessary rather than uniformly across the entire device.
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
This configuration enhances luminescent efficiency by reducing abnormal light colors and increasing external quantum efficiency, as demonstrated by improved light emission spectra, nearly doubling the efficiency in specific regions.
Implementation Method 1
a connecting layer formed by an electron-transporting material and provided between the first light emitting sub-layer and the second light emitting sub-layer
Implementation Method 2
an organic semiconductor light emitting material emits a light by current carriers injection and recombination with being driven by an electrical field
Data Source
AI summary
Embodiments of the present invention disclose an organic electroluminescent display device and a display apparatus. The display device includes: a base substrate, and a first electrode, an organic light emitting layer and a second electrode arranged sequentially on the base substrate, the organic light emitting layer includes a first light emitting sub-layer and a second light emitting sub-layer arranged in stack, the first light emitting sub-layer having a coverage area less than that of the second light emitting sub-layer; a connecting layer is formed by an electron-transporting material and provided between the first light emitting sub-layer and the second light emitting sub-layer; and projection areas of a pattern of the connecting layer and the first light emitting sub-layer on the base substrate are overlapped with each other. It may suppress abnormal color of light from the organic light emitting layer and improve the luminescence efficiency of the display device.