OLED Color Conversion Layer Nanocrystal Efficiency
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Solution Overview
Problem
Existing OLED display technologies face inefficiencies in converting white light into desired colors, particularly in red and green emissions, due to limitations in materials and processes, leading to loss of emission during color filtering and filtration requirements.
Innovation Solution
Incorporating a color conversion layer between the white light emitting diode and the color filter layer, utilizing semiconductor nanocrystals dispersed in an organic binding material, such as polycarbonate or polyacrylate, to enhance the conversion of white light into red and green colors, while maintaining blue light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a color filter layer is used to convert white light to color, then color display is achieved, but much of the OLED emission is lost in the color filtering process
Solution Approach 1:
The patent introduces a color conversion layer containing quantum dots as an intermediary between the white light OLED and the color filter layer. This quantum dot layer converts specific wavelengths of white light into desired colors through photoluminescence, reducing the need for aggressive color filtering and thereby minimizing OLED emission loss while maintaining color display capability
Solution Approach 2:
The patent utilizes the size-dependent optical properties of quantum dots, where changing the particle size changes the emission wavelength. By controlling quantum dot size distribution, the system can optimize color output to match the OLED spectrum, reducing the filtering requirement and energy loss
2Productivity
If blue OLED emission is used for down conversion, then color conversion efficiency improves, but material availability and emission intensity are insufficient
Solution Approach 1:
The patent employs composite material systems including various quantum dot compositions (CdSe, CdTe, InP, perovskite quantum dots) combined with appropriate ligands and matrix materials. This composite approach allows optimization of both emission intensity and stability, addressing the reliability concerns of single-material systems while maintaining high color conversion efficiency
Solution Approach 2:
The patent systematically varies quantum dot composition parameters (core material, shell material, size, surface treatment) to optimize emission characteristics. By changing these parameters, the system achieves sufficient emission intensity and lifetime while maintaining commercial competitiveness
3Measurement precision
If inorganic nanocrystals are used for color conversion, then emission bands narrow and wavelength control improves, but material availability is limited
Solution Approach 1:
The patent utilizes multiple types of inorganic nanocrystals (CdSe, CdTe, InP, perovskite quantum dots) with different bandgap properties. This composite nanocrystal approach maintains the narrow emission band advantage while expanding material availability and enabling coverage across the entire visible spectrum through selective combination of different nanocrystal types
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 approach increases the efficiency of red and green color emission output, improving luminance and color gamut in OLED displays, while ensuring accurate and pleasing color reproduction by optimizing the size and distribution of subpixels in the color conversion matrix.
Implementation Method 1
This high-energy emission is then down converted to less energetic green and red by color conversion
Implementation Method 2
The color conversion layer consists of nanocrystals, which are dispersed in a transparent binding material and may be employed in either down-emitting or up-emitting color OLED display devices
Implementation Method 3
This color conversion can be accomplished either by use of organic materials which absorb the high-energy emission and photo-luminance or by inorganic nanocrystals
Implementation Method 4
This color conversion can be accomplished either by use of organic materials which absorb the high-energy emission and photo-luminance
Implementation Method 5
This color conversion can be accomplished either by use of organic materials which absorb the high-energy emission and photo-luminance
Data Source
AI summary
A color display device that increases the efficiency of use of white light emitted from an organic light-emitting diode (OLED) in producing an improved color display. The device includes a plurality of color OLED display pixels, which include an OLED, a color filter layer, and a color conversion matrix sandwiched between the OLED and the color filter layer. The color filter layer has a plurality of color filter elements including a red, green and blue color filter element. The array of subpixels comprised in the color conversion matrix is composed of semiconductor nanocrystals uniformly dispersed in an organic binding material, which may be employed in either down-emitting or up-emitting color OLED display devices.