OLED Mixed Layer for Carrier Injection Barrier Reduction
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Solution Overview
Problem
The efficiency and lifetime of organic light-emitting display devices are compromised due to high carrier injection barriers and improper carrier recombination in existing technologies.
Innovation Solution
An organic light-emitting display apparatus is designed with a substrate hosting an organic light-emitting device featuring a dielectric layer comprising a hole injection layer, a hole transporting layer, a first mixed layer, an emission layer, an electron transporting layer, and an electron injection layer, where the first mixed layer is doped with functional materials for electron or hole control, and a second mixed layer is added between the emission and electron transporting layers to optimize carrier injection and recombination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional organic light-emitting device structure is used, then device simplicity is maintained, but carrier injection barrier is high and recombination efficiency is low
Solution Approach 1:
The organic light-emitting device is segmented into multiple functional layers including hole injection layer, hole transporting layer, first mixed layer, emission layer, second mixed layer, electron transporting layer, and electron injection layer. Each layer is specifically designed to perform a particular function in carrier transport and recombination, thereby reducing injection barriers and improving recombination efficiency without creating an unmanageably complex structure.
Solution Approach 2:
Different layers are assigned different material compositions and properties optimized for their specific functions. The mixed layers contain both hole transporting and electron transporting materials with specific doping concentrations, while the emission layer contains luminescent dopants. This local optimization of material properties at different positions within the device enables efficient carrier injection and recombination while maintaining overall structural coherence.
2Productivity
If mixed layers with functional materials are added to control carrier injection, then carrier recombination efficiency is improved, but device structure becomes more complex
Solution Approach 1:
The mixed layers serve multiple functions simultaneously: they act as transition layers between hole and electron transporting regions, provide carrier injection pathways, control recombination zones through doping, and maintain energy level alignment. This multi-functionality reduces the need for additional separate layers, improving recombination efficiency while limiting structural complexity.
Solution Approach 2:
The first and second mixed layers act as intermediary layers between the hole transporting and electron transporting sections of the device. These intermediate layers facilitate smooth carrier transition and energy level matching, enabling efficient carrier injection and recombination without requiring direct contact between dissimilar materials, thus improving productivity while managing complexity.
3Reliability
If carrier injection barrier is reduced through material optimization, then device efficiency increases, but manufacturing precision requirements increase
Solution Approach 1:
The invention optimizes carrier injection by carefully selecting and adjusting material parameters such as HOMO and LUMO energy levels, doping concentrations, and layer thicknesses. The mixed layers use specific ratios of hole and electron transporting materials with tailored energy level alignments to reduce injection barriers. While this requires precise manufacturing control, the use of organic materials and solution processing techniques helps achieve the necessary precision.
Solution Approach 2:
The mixed layers are composed of composite materials combining hole transporting and electron transporting compounds in specific ratios. These composite materials provide built-in energy level alignment and dual carrier transport capability, reducing injection barriers through material composition rather than relying solely on precise thickness control. Examples include mixtures of TPD/PBD, NPB/Alq3, or TCTA/BPhen with controlled doping concentrations.
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 decreases carrier injection barriers, controls the carrier recombination region, and enhances the efficiency and longevity of the organic light-emitting device by optimizing carrier injection and recombination processes.
Implementation Method 1
said first mixed layer is doped with a first functional material; and said second mixed layer is doped with a second functional material
Implementation Method 2
The latter emits visible lights through radiative relaxation
Data Source
AI summary
The present invention provides an organic light-emitting display apparatus where an organic light-emitting device comprises an anode layer, a cathode layer, and an organic light-emitting dielectric layer disposed between the anode layer and the cathode layer; organic light-emitting dielectric layer comprises a hole injection layer, a hole transporting layer, a first mixed layer, an emission layer, an electron transporting layer, and an electron injection layer sequentially disposed; wherein first mixed layer is a mixed material layer consisting of a hole transporting material and an electron transporting material, and first mixed layer is doped with either of a material having an electron blocking function and a material having a hole control function. It can decrease injection barrier of carriers of holes and electrons in the organic light-emitting device, control carrier injection rate and position of carrier recombination region, and raise the recombination efficiency of the carriers, thereby achieving a high efficiency, long lifetime organic light-emitting device.