Bottom Emitting OLED Refractive Index Gradient Layers
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Solution Overview
Problem
Bottom emission OLEDs suffer from high reflectance of metal layers in the thin film transistor, leading to strong reflected images and decreased image quality, which existing solutions like polarizers address by reducing light emission efficiency and increasing power consumption.
Innovation Solution
Incorporating a dielectric thin film layer group with progressively increasing refractive indices between the base substrate and the thin film transistor, comprising two stacked dielectric thin film layers with specific refractive index ratios and materials, to reduce surface reflectance and light loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If polarizers are used to reduce reflectance of metal layers, then image quality is improved, but light emission efficiency decreases and power consumption increases
Solution Approach 1:
The patent introduces dielectric thin film layer groups as intermediary layers between the base substrate and metal layers. These intermediary layers with progressively increasing refractive indices mediate the optical interaction, reducing reflectance without the energy losses associated with polarizers. The dielectric layers act as optical mediators that manipulate light reflection through refractive index gradients rather than absorption-based polarizing mechanisms.
Solution Approach 2:
The patent applies parameter changes by systematically varying the refractive indices of dielectric thin film layers in a progressive sequence from the base substrate towards the metal layers. This parameter optimization (refractive index gradient) enables controlled reduction of surface reflectance while maintaining high light transmission, thereby improving image quality without increasing power consumption.
2Object-affected harmful factors
If polarizers are used to reduce reflectance of metal layers, then image quality is improved, but light emission efficiency decreases
Solution Approach 1:
Dielectric thin film layer groups serve as optical intermediaries that reduce metal layer reflectance through refractive index management. These layers minimize light loss by using dielectric materials with low absorption coefficients, allowing light to pass through with minimal energy loss compared to polarizer-based solutions.
Solution Approach 2:
The patent employs composite material structures consisting of multiple dielectric thin film layers with different refractive indices stacked in a specific sequence. This composite structure creates a gradient that progressively adapts the optical impedance between the base substrate and metal layers, reducing reflectance while maintaining high light emission efficiency through optimized material composition.
3Object-affected harmful factors
If dielectric thin film layer groups with progressively increasing refractive indices are used, then surface reflectance is reduced, but device structure becomes more complex
Solution Approach 1:
The patent segments the optical path into multiple dielectric thin film layer groups, each with progressively increasing refractive indices. This segmentation allows the complex function of reflectance reduction to be divided into simpler, manageable layers, where each layer contributes incrementally to the overall optical performance, making the complex function achievable through modular layering.
Solution Approach 2:
The patent addresses reflectance reduction by adding a dimensional aspect - the refractive index dimension - rather than complicating the lateral structure. By creating a gradient in the refractive index property across multiple layers, the solution manages optical complexity through material property variation rather than geometric complexity, effectively reducing surface reflectance while maintaining structural simplicity.
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
Decreases surface reflectance of metal layers by 20-40% compared to using polarizers, improving image quality and display effect while minimizing light loss.
Implementation Method 1
Each dielectric thin film layer group comprises at least two stacked dielectric thin film layers, the refractive indices of which are increased progressively from the base substrate towards the thin film transistor
Implementation Method 2
Dielectric thin film layers contained in each dielectric thin film layer group have a same optical thickness
Data Source
Figure 1a~1c
Figure 1d~2
Figure 3~4b
AI summary
A bottom emission organic electroluminescence display, a preparation method thereof, and a display apparatus are provided. The display includes a base substrate (100), and at least one dielectric thin film layer group (200) and a thin film transistor (300) that are successively arranged on the base substrate; each dielectric thin film layer group (200) comprising at least two stacked dielectric thin film layers (201, 202, 203), the refractive indices of which are increased progressively from the base substrate towards the thin film transistor. Because at least one group of at least two stacked dielectric thin film layers, the refractive indices of which are increased progressively from the base substrate towards the thin film transistor, are added between the base substrate and the thin film transistor, not only the reflectance of the surface of the metal layers contained in the thin film transistor (300) may be decreased, but also the loss rate of the emitted light may be decreased, thereby improving the image quality and display effect.