Broadband OLED Device with Segmented Light-Emitting Layers
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Solution Overview
Problem
Broadband OLEDs face challenges in achieving efficient light emission and hue stability as current variations lead to hue shifts, and existing single-layer OLEDs have manufacturing difficulties and lower stability compared to multi-layer structures.
Innovation Solution
A broadband OLED device with two spaced electrodes, comprising a green-emitting layer with an anthracene host and a 2,6,9-triaminoanthracene dopant, and a red-emitting layer with a host and red dopant, designed to maintain hue stability and efficiency with varying current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single light-emitting layer is used to achieve broadband emission, then the device structure is simpler, but manufacturing precision is difficult to control and stability is lower
Solution Approach 1:
The patent divides the single light-emitting layer into two separate light-emitting layers, each with specific dopant concentrations. This segmentation allows each layer to be optimized independently, improving manufacturing precision and device stability while maintaining broadband emission capability.
2Illumination intensity
If dopant concentration is increased to achieve broadband emission, then emission spectrum broadens, but manufacturing precision becomes more difficult
Solution Approach 1:
Instead of using one layer with high dopant concentration, the patent segments the emission into two layers with different dopant concentrations. This approach broadens the emission spectrum while reducing the manufacturing difficulty associated with controlling high dopant concentrations in a single layer.
3Ease of operation
If current is varied to change luminance intensity, then brightness control is achieved, but hue shifts occur
Solution Approach 1:
The patent segments the broadband emission into two distinct layers with different emission characteristics. This segmentation causes the layers to respond differently to current variations, and their combined output maintains hue stability while allowing luminance control.
Solution Approach 2:
The patent changes the physical parameters of the two light-emitting layers, specifically their dopant concentrations and emission characteristics. This parameter differentiation ensures that when current varies, the layers compensate for each other's hue shifts, maintaining overall color stability.
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 solution provides a broadband light-emitting structure with improved efficiency and low voltage requirements, minimizing hue changes with current variations and enhancing luminance stability.
Implementation Method 1
A light-emitting layer having a host material and one or more luminescent dopant(s) can achieve light emission from both the host and the dopant(s) resulting in a broadband emission in the visible spectrum if the energy transfer from the host material to the dopant(s) is incomplete
Implementation Method 2
An organic light-emitting diode device, also called an OLED, commonly includes an anode, a cathode, and an organic electroluminescent (EL) unit sandwiched between the anode and the cathode
Implementation Method 3
A light-emitting layer having a host material and one or more luminescent dopant(s) can achieve light emission from both the host and the dopant(s) resulting in a broadband emission in the visible spectrum if the energy transfer from the host material to the dopant(s) is incomplete
Implementation Method 4
An organic light-emitting diode device, also called an OLED, commonly includes an anode, a cathode, and an organic electroluminescent (EL) unit sandwiched between the anode and the cathode
Data Source
Figure 1~3
AI summary
An OLED device having two spaced electrodes (30, 90), and including a first light-emitting layer (5Og) that produces green emission and includes an anthracene host and a 2, 6-diaminoanthracene light-emitting dopant, and a second light-emitting layer (5Or) that produces red emission and includes a host and a red light-emitting dopant.