Polyimide Flexible OLED Substrate with Bulge Groove Structure
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Solution Overview
Problem
Conventional OLED devices suffer from low light extraction efficiency due to refractive index mismatches and waveguide effects, leading to significant light loss and decay.
Innovation Solution
A flexible substrate with a bulge and groove structure, made from polyimide with inorganic oxide particles, is used to enhance light extraction, combined with a transparent first electrode and a reflective second electrode, optimizing the layered structure for improved illumination efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional planar substrate is used in OLED, then the device structure is simple and easy to manufacture, but light extraction efficiency is low due to refractive index mismatches and waveguide effects
Solution Approach 1:
The substrate surface is modified with a bulge and groove structure, transforming the planar surface into a curved topology. This curvature structure disrupts the waveguide effect and refractive index mismatch at the substrate interface, enabling more light to escape from the OLED device. The bulge regions act as light scattering centers while groove regions facilitate light extraction, collectively improving light extraction efficiency without complicating the manufacturing process
Solution Approach 2:
The substrate incorporates a micro-scale porous or textured structure with bulges and grooves. This porous-like topology increases the surface area and creates multiple interfaces for light scattering and extraction. The three-dimensional structure provides numerous light extraction pathways, reducing total internal reflection and improving overall light extraction efficiency while maintaining manufacturing feasibility through standard substrate processing techniques
2Loss of energy
If a flexible substrate with bulge and groove structure is used, then light extraction efficiency is significantly enhanced, but the substrate structure becomes more complex
Solution Approach 1:
The substrate employs a periodic array of bulge and groove structures with controlled curvature radii. The bulge portions have a first curvature radius while groove portions have a second curvature radius, creating a predictable geometric pattern. This regular curved structure achieves effective light extraction while maintaining manufacturing simplicity through replication techniques, avoiding the need for complex random surface modifications
3Adaptability or versatility
If polyimide material is used for flexible substrate, then the substrate achieves flexibility and light extraction improvement, but manufacturing precision requirements increase
Solution Approach 1:
The substrate structure parameters including bulge height, groove depth, curvature radii, and pattern spacing are optimized within specific ranges to achieve the desired light extraction performance. By controlling these geometric parameters rather than requiring perfect precision, the design accommodates polyimide material characteristics and manufacturing tolerances while still achieving significant light extraction improvement and flexibility
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 flexible substrate with a bulge and groove structure significantly enhances light extraction efficiency, increasing the current efficiency of OLEDs by up to 80% compared to traditional glass substrates.
Implementation Method 1
a flexible substrate with a bulge and groove structure, made from polyimide with inorganic oxide particles, is used to enhance light extraction
Implementation Method 2
Because refractive index mismatches between the interferences of the layered structure and the waveguide effect, a light produced by the organic layers will be reflected back
Implementation Method 3
a second electrode on the organic light emitting layer, wherein the flexible substrate comprises polyimide
Data Source
AI summary
Disclosed is an organic light emitting diode (OLED), including a flexible substrate having a surface with a bulge and groove structure. The OLED also includes a first electrode on the flexible substrate, an organic light emitting layer on the first electrode, and a second electrode on the organic light emitting layer. The flexible substrate includes polyimide.