Phase Change Thin Film for OLED Light Extraction
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Solution Overview
Problem
Existing organic light emitting diode (OLED) devices suffer from low light extraction efficiency due to total reflection at the boundary surfaces between layers with different refractive indices, resulting in significant light loss within the device, and current methods to improve this, such as forming light scattering layers or micro lens arrays, are costly and complex.
Innovation Solution
A phase change material is used to form a thin film layer that can change its state from amorphous to crystalline or vice versa with heat or light, functioning as a light scattering layer and allowing for the formation of fine unevenness patterns, thereby enhancing light extraction efficiency without the need for high-cost or complex processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional light scattering layers or micro lens arrays are formed to improve light extraction efficiency, then light extraction efficiency is improved, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent changes the refractive index parameter of the substrate by forming a gradient refractive index layer, transitioning from a uniform refractive index structure to a gradient structure. This parameter change enables improved light extraction efficiency without requiring complex light scattering layers or micro lens arrays, thus resolving the contradiction between energy loss reduction and manufacturing complexity
Solution Approach 2:
The patent utilizes phase transition materials (such as GeSbTe alloy) that can transition between amorphous and crystalline states with different refractive indexes. By controlling the phase state of the gradient refractive index layer, the optical properties can be adjusted to optimize light extraction, achieving improved light extraction efficiency through a relatively simple phase change process rather than complex structural modifications
2Loss of energy
If light scattering layers or micro lens arrays are formed to improve light extraction efficiency, then light extraction efficiency is improved, but manufacturing cost increases
Solution Approach 1:
The patent employs parameter changes by forming a gradient refractive index layer with continuously varying refractive index from the substrate to the organic light emitting layer. This approach achieves improved light extraction efficiency through material composition gradient rather than complex structural additions, significantly reducing manufacturing cost compared to traditional light scattering layers or micro lens arrays
Solution Approach 2:
The patent uses composite materials, specifically GeSbTe alloy combining multiple elements, to create the gradient refractive index layer. This composite material approach enables tuning of optical properties through composition control, achieving cost-effective light extraction improvement without requiring expensive complex structural components
3Adaptability or versatility
If multiple layers with different refractive indexes are used in OLED device, then optical functionality is achieved, but total reflection at boundary surfaces causes significant light loss
Solution Approach 1:
The patent applies parameter changes by implementing a continuous gradient refractive index profile across the interface between substrate and organic light emitting layer. This gradient structure eliminates abrupt refractive index boundaries, preventing total internal reflection while maintaining necessary optical functionality, thus resolving the contradiction between optical functionality and light loss
Solution Approach 2:
The gradient refractive index layer acts as an intermediary between the substrate and the organic light emitting layer, providing a gradual transition zone for refractive index. This intermediary structure facilitates smooth optical transition, preventing total reflection at sharp boundaries while maintaining optical functionality, effectively resolving the contradiction
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 phase change thin film layer effectively reduces light loss within the OLED device, substantially improving light extraction efficiency by converting waveguide mode light into discharge mode light, achieving comparable results to traditional methods but with simpler and less expensive processes.
Implementation Method 1
A phase change material is used to form a thin film layer that can change its state from amorphous to crystalline or vice versa with heat or light
Implementation Method 2
functioning as a light scattering layer and allowing for the formation of fine unevenness patterns, thereby enhancing light extraction efficiency
Implementation Method 3
light generated in the organic light emitting layer 130 is reflected in the cathode layer 140 or is discharged toward the anode layer 120, most of the generated light is finally discharged toward the anode layer 120
Implementation Method 4
refraction or reflection is generated in the respective boundary surfaces due to the difference in the refractive indexes of the boundary surface
Data Source
AI summary
Disclosed are an organic light emitting diode device and a method of fabricating the organic light emitting diode device capable of achieving high light extraction efficiency even without a high-cost and complicated process. The organic light emitting diode device according to an exemplary embodiment of the present disclosure includes a substrate; a phase change thin film layer formed on the substrate and formed of a phase change material changeable from an amorphous state to a crystalline state or from a crystalline state to an amorphous state; and an anode electrode layer, an organic light emitting layer and a cathode electrode layer which are sequentially formed on the phase change thin film layer.