Dual Emitting Layer OLED Structure for Charge Balance and Lifespan
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Solution Overview
Problem
Existing organic light emitting devices face challenges in achieving improved light emitting efficiency and device lifespan, particularly in tandem structures with multiple light emitting layers.
Innovation Solution
A light emitting device is designed with a specific configuration including a first and second light emitting layer, each with distinct host materials and dopants, and a charge generation layer, along with electron and hole transport regions, to enhance light emission efficiency and lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tandem organic light emitting device with multiple light emitting layers is constructed, then light emitting efficiency and device lifespan are improved, but device complexity increases
Solution Approach 1:
The device is divided into multiple independent light emitting layers (first light emitting layer with blue emission and second light emitting layer with red emission) that can be independently optimized and manufactured. Each layer has its own host materials, dopants, and transport regions, allowing specialized optimization for each wavelength while maintaining overall device functionality and extending lifespan through reduced operational stress on individual layers.
Solution Approach 2:
The patent employs composite material systems in each light emitting layer, combining specific host materials (e.g., Alq3, BCP) with dopant materials (e.g., Ir(ppy)3, AlxGa1-xInP2O3 quantum dots) to achieve optimal light emission properties. This composite approach enables tailored energy levels and charge transport characteristics that improve device reliability and lifespan while managing the complexity through systematic material selection.
2Productivity
If multiple light emitting layers with different wavelengths are implemented, then light emitting efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent systematically varies key parameters including host material composition ratios (e.g., Alq3:BCP ratios), dopant concentrations, and layer thicknesses to optimize each light emitting layer for its specific wavelength. By establishing specific parameter ranges (e.g., dopant concentration of 1-10 wt%, layer thickness of 50-200 nm), the patent achieves improved light emitting efficiency while providing manufacturing guidelines that control precision requirements.
Solution Approach 2:
Each light emitting layer is designed with locally optimized properties, including specific host materials, dopants, and thicknesses tailored to emit at different wavelengths (blue vs. red). The charge transport regions and electron injection layers are also locally optimized for each layer's specific requirements, enabling high efficiency while allowing independent manufacturing control of each layer's parameters.
3Reliability
If charge generation layers and transport regions are added between light emitting layers, then device lifespan is improved, but device complexity increases
Solution Approach 1:
Charge generation layers and transport regions serve as intermediary components between the light emitting layers, facilitating efficient charge carrier generation, transport, and injection. These intermediary layers (including hole transport regions, electron transport regions, and charge generation layers with specific dopants) enable the multiple light emitting layers to operate independently and efficiently, improving device lifespan through reduced charge carrier recombination losses while managing complexity through systematic integration.
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 device achieves increased light emitting efficiency and extended lifespan by optimizing the energy levels and compositions of the host materials in the light emitting layers, enhancing overall performance.
Implementation Method 1
A hole provided from the anode and an electron provided from the cathode are combined in the light emitting layer to form an exciton, and light corresponding to energy between the hole and the electron is generated from the exciton.
Data Source
AI summary
Provided is a light emitting device including a first electrode, a hole transport region on the first electrode, a first light emitting layer on the hole transport region and emitting light of a first wavelength, a second light emitting layer on the hole transport region and emitting light of a second wavelength different from the first wavelength, an electron transport region on the first light emitting layer and the second light emitting layer, and a second electrode on the electron transport region. The second light emitting layer includes a first sub-light emitting layer including a first host having a first hole transporting host and a first electron transporting host and a dopant emitting light of the second wavelength, and a second sub-light emitting layer including a second host and a second hole transporting host, but not including the dopant. The light emitting device provides improved light emitting efficiency.