Color Conversion Organic EL Display with Microlens Array
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Solution Overview
Problem
Current organic EL display technologies face challenges in achieving high-efficiency multicolor emission with stable hue balance over time, and in forming fine patterns for color conversion films without using metal masks or expensive laser scanning devices, which leads to issues like concentration quenching, electrode disconnection, and reduced display definition.
Innovation Solution
A color conversion type organic EL display is formed by bonding an organic EL substrate with a color filter substrate, where the organic EL layer is sandwiched between a lower reflective electrode and an upper transparent electrode, and a color conversion layer is directly formed on the upper transparent electrode, using a polymer material and a bank to separate pixel regions, allowing for high-temperature annealing to remove moisture and solvents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the concentration of color conversion material in the color conversion film is increased to improve light absorption efficiency, then the absorbance increases, but concentration quenching occurs causing energy loss and reduced emission efficiency
Solution Approach 1:
The patent applies local quality by creating spatial variation in color conversion material concentration. The microlens array concentrates incident light into localized regions, allowing higher material concentration and absorbance in the focal regions while maintaining lower average concentration throughout the film, thereby avoiding concentration quenching while improving light absorption efficiency.
Solution Approach 2:
The patent introduces a spatial dimension through the microlens array structure. By focusing light in the thickness direction (z-dimension) of the color conversion film, the system achieves enhanced absorbance without uniformly increasing material concentration, thus avoiding the concentration quenching effect that occurs in uniformly thick, high-concentration films.
2Use of energy by moving object
If a thick color conversion film is used to increase light absorbance and maintain color conversion efficiency, then the film thickness increases, but electrode patterns disconnect at step portions and display definition decreases
Solution Approach 1:
The patent uses the microlens array to focus light in the thickness direction, enabling effective color conversion in a thinner film. This dimensional approach to light concentration allows the system to achieve high absorbance without increasing lateral film thickness, thereby preventing electrode disconnection and maintaining display definition.
Solution Approach 2:
The microlens array creates multiple focused light paths that copy and concentrate incident light into the color conversion material. This optical copying mechanism achieves enhanced light-matter interaction in a thin film without requiring physically thick material layers, thus avoiding manufacturing defects while maintaining conversion efficiency.
3Adaptability or versatility
If simultaneous excitation of multiple emissive materials is used to achieve multicolor emission, then the emission balance changes over time and current, causing hue instability
Solution Approach 1:
The patent segments the color generation process into two independent parts: (1) a single-emissive-material organic EL layer that provides stable monochromatic emission, and (2) a color conversion film that converts the stable emission into multiple colors. This segmentation isolates the emission source from color variation, ensuring stable hue balance over time and current while maintaining multicolor capability.
Solution Approach 2:
The color conversion film acts as an intermediary between the stable monochromatic emission from the organic EL layer and the final multicolor output. By introducing this intermediate conversion layer, the system achieves multicolor emission without directly exciting multiple emissive materials, thereby maintaining emission stability while enabling color versatility.
4Use of energy by moving object
If a color conversion film is formed directly on the organic EL device to improve efficiency, then light absorption improves, but residual moisture and solvent in the film cause organic EL layer alteration and display faults
Solution Approach 1:
The patent applies preliminary action by performing high-temperature annealing (200°C or higher) on the color conversion film before bonding it to the organic EL device. This pre-treatment removes residual moisture and solvent from the film in advance, preventing subsequent degradation of the organic EL layer and ensuring long-term display stability while maintaining the film's light absorption efficiency.
Solution Approach 2:
The high-temperature annealing process provides beforehand cushioning against potential reliability issues. By removing harmful moisture and solvent residues before the film contacts the organic EL layer, the system prevents future degradation and display faults, ensuring reliable operation throughout the device lifetime.
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 configuration enables accurate control of film thickness, efficient light incidence, and long-term stability of the organic EL display with minimal chromaticity variation and reduced crosstalk, achieving high-definition multicolor emission.
Implementation Method 1
the color conversion layer absorbs EL light emitted by the emission layer
Implementation Method 2
emits light with a wavelength different from that of the EL light
Implementation Method 3
a lower reflective electrode... an upper transparent electrode
Implementation Method 4
allowing for high-temperature annealing to remove moisture and solvents
Data Source
AI summary
A color conversion type organic EL display can comprise an organic EL substrate that includes a substrate, a lower reflective electrode, a bank, and an organic EL layer sandwiched between the lower reflective electrode and an upper transparent electrode. The color conversion type organic EL display can further comprise a color filter substrate in which a black matrix and a color filter are formed in a pattern on a transparent substrate by a photo process, and which has a pixel region separated by the black matrix. The organic EL substrate and the color filter substrate can be bonded together and positioned such that the pixel region of the EL substrate and the pixel region of the color filter substrate are opposed.