Chiral Liquid Crystal OLED Layers for Band-Edge Light Extraction
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Solution Overview
Problem
Current OLEDs and LEDs face challenges in achieving efficient light emission due to the trapping of in-plane emitted light, leading to low energy efficiency and high manufacturing costs, especially when attempting to produce larger devices with complex photonic crystal structures.
Innovation Solution
The use of a series of photopolymerizable, chiral liquid crystalline layers solvent cast on a substrate, where each layer is aligned and photopolymerized, creating a robust polymer matrix with an optically uniform chiral liquid crystalline structure. This approach allows for the production of a band-edge emitting OLED with a simpler structure and reduced manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If complex photonic crystal structures are integrated with OLEDs to achieve enhanced light emission and energy efficiency through stimulated emission, then energy efficiency and light emission performance are improved, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent extracts the essential photonic crystal functionality and implements it through a simpler chiral liquid crystalline structure rather than complex periodic dielectric layers. The chiral liquid crystal layer alone provides the necessary optical feedback and stimulated emission enhancement without requiring multiple alternating high/low refractive index layers, thus reducing device complexity while maintaining energy efficiency improvements.
Solution Approach 2:
The patent changes the fundamental parameter of photonic crystal structure from periodic dielectric layers to a chiral liquid crystalline phase. This parameter change allows the system to achieve photonic band gap effects and stimulated emission enhancement through the helical structure of chiral liquid crystals, simplifying the device architecture while preserving the energy efficiency benefits of vertical light emission.
2Illumination intensity
If complex photonic crystal structures are integrated with OLEDs to achieve enhanced light emission, then light emission performance is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent extracts the light emission enhancement function from complex photonic crystal structures and achieves it through a single chiral liquid crystalline layer. This layer provides the necessary optical feedback for stimulated emission without requiring the fabrication of multiple alternating dielectric layers, significantly simplifying the manufacturing process while maintaining enhanced light emission performance.
Solution Approach 2:
The patent uses a composite material approach by combining chiral liquid crystalline materials with the OLED structure. The chiral liquid crystal layer serves as both the photonic crystal equivalent and an additional functional layer, providing optical feedback while being compatible with standard OLED fabrication processes, thus improving light emission without proportionally increasing manufacturing complexity.
3Device complexity
If conventional OLED structures are used with in-plane light emission, then device simplicity is maintained, but energy efficiency decreases due to light trapping
Solution Approach 1:
The patent introduces dynamics into the system by using a liquid crystalline material that can be oriented and aligned. The chiral liquid crystal layer provides dynamic optical feedback that promotes vertical light emission, transforming the static in-plane emission pattern into a dynamic vertical emission pattern. This dynamic change enables energy efficiency improvement while maintaining relatively simple device structure.
Solution Approach 2:
The patent implements optical feedback through the chiral liquid crystalline structure. The helical structure of the chiral liquid crystal provides feedback to the emitted light, promoting stimulated emission in the vertical direction. This feedback mechanism converts the conventional in-plane emission into vertical emission, reducing light trapping and improving energy efficiency without significantly complicating 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
This method enables the production of highly energy-efficient band-edge emitting OLEDs with improved operating lifetimes and color gamut, while reducing manufacturing costs and complexity, particularly for larger devices.
Implementation Method 1
a series of photopolymerizable, chiral liquid crystalline layers solvent cast on a substrate, where each layer is aligned and photopolymerized
Implementation Method 2
yield stimulated emission of light from the light emitting layers
Implementation Method 3
Band edge emission enhanced organic light emitting diode utilizing chiral liquid crystalline emitter
Implementation Method 4
light propagating external to the photonic crystal medium will be completely reflected from the medium's surface if it has a wavelength within the stop band
Implementation Method 5
Photonic crystals are dielectric media that have a periodic variation of refractive index of light through their extent
Implementation Method 6
the director 230 rotates so as to sweep out a helix. Thus the individual liquid crystal molecules combine into a helical structure
Data Source
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AI summary
Disclosed herein is a light emitting device and method of manufacturing such a device comprised of a series of photopolymerizable, chiral liquid crystalline layers that can be solvent cast on a substrate. The mixture of chiral materials in each successive layer may be blended in such a way that each layer has the same chiral pitch. Further the chiral materials in each layer may also be blended so that the ordinary and extraordinary refractive indices in each layer match the other layers such that the complete assembly of layers will optically function as a single relatively thick layer of chiral liquid crystal. The chiral nematic material in each layer can spontaneously adopt a helical structure with a helical pitch. The light emitting layers of the light emitting device can further comprise electroluminescent material that emits light into the band edge light propagation modes of the photonic crystal.