Wavelength Conversion Layer for OLED Light Efficiency
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Solution Overview
Problem
Organic light emitting display devices using a white organic light emitting layer and color filters face disadvantages in light efficiency and color reproducibility.
Innovation Solution
A display device structure incorporating a substrate, switching elements, insulating layers, pixel defining films, lower electrodes, reflective patterns, light emitting layers, upper electrodes, and wavelength conversion layers, with wavelength conversion layers disposed on the upper electrodes to enhance light efficiency and color reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a white organic light emitting layer with color filters is used, then the display device can be manufactured with simpler color generation process, but light efficiency deteriorates and color reproducibility worsens
Solution Approach 1:
The invention extracts and removes the color filters from the display structure, replacing them with a white organic light emitting layer that directly emits white light. This eliminates the light loss associated with color filter absorption while maintaining the ability to generate colored light through spatial separation of red, green, and blue emitting regions.
Solution Approach 2:
The invention changes the emission parameters of the organic light emitting layer by using different organic compounds or doping materials in different regions to emit red, green, or blue light directly. This allows the same layer structure to produce different colors through material composition changes rather than optical filtering.
2Ease of manufacture
If a white organic light emitting layer with color filters is used, then the manufacturing process is simplified, but color reproducibility deteriorates
Solution Approach 1:
The invention applies local quality by using different organic light emitting materials with specific emission characteristics in different spatial regions. Each region (red, green, blue) is optimized with materials that emit the desired wavelength range, achieving high color reproducibility through localized material selection rather than uniform filtering.
3Device complexity
If color filters are used to generate red, green, and blue colors, then the device structure is simpler, but light efficiency is reduced due to filter absorption
Solution Approach 1:
The invention removes the color filter components from the device structure and replaces them with directly emitting organic light emitting materials. This extraction eliminates the energy loss pathway through filter absorption while maintaining color generation capability through spatially separated red, green, and blue emitting regions.
4Ease of manufacture
If color filters are used to produce colors, then the manufacturing process is easier, but the viewing angle and color purity are compromised
Solution Approach 1:
The invention changes the fundamental parameter of color generation from optical filtering to direct electroluminescence. By using organic compounds that emit specific wavelengths when electrically excited, the system achieves high color purity defined by narrow emission spectra, eliminating the broad spectral transmission characteristics inherent to color filter approaches.
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
Improves light efficiency and color reproducibility by utilizing wavelength conversion layers to convert blue light into red and green light, enhancing color purity and viewing angle.
Implementation Method 1
wavelength conversion layers to convert blue light into red and green light
Implementation Method 2
a reflective pattern disposed on the insulating layer exposed through the opening and spaced apart from the lower electrode
Data Source
AI summary
A display device includes: a substrate; a switching element on the substrate; an insulating layer on the switching element; a pixel defining film on the insulating layer and including an opening overlapping a part of the insulating layer; a lower electrode on a side surface of the pixel defining film defining the opening and electrically connected with the switching element; a reflective pattern on the insulating layer exposed through the opening and spaced apart from the lower electrode; a light emitting layer on the lower electrode and the reflective pattern; an upper electrode on the light emitting layer; and a wavelength conversion layer on the upper electrode and arranged in the opening.