Monolithic Display Integrating GaN and OLED Pixels
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Solution Overview
Problem
Existing color image display devices face challenges with the short lifetime of organic light-emitting diodes at high luminance levels, particularly for blue light emission, and the bulk and manufacturing cost constraints of color conversion elements in inorganic gallium nitride light-emitting diode devices.
Innovation Solution
A monolithic display device integrating gallium nitride light-emitting diodes for blue light and organic light-emitting diodes for green and red light, with a shared semiconductor layer and interconnected electrodes, and a method of manufacturing involving metal connection pads, insulating layers, and conductive levels to control and optimize light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If organic light-emitting diodes are used to emit blue light at high luminance levels, then color image display is achieved, but the lifetime of the device is short
Solution Approach 1:
The device is divided into three distinct pixel types: first pixels with gallium nitride diodes for blue light, second pixels with organic diodes for green light, and third pixels with organic diodes for red light. This segmentation allows each pixel type to use the most appropriate technology for its specific wavelength requirement, avoiding the use of organic diodes for blue light where they have short lifetime.
Solution Approach 2:
Different materials and structures are used in different parts of the device according to local requirements. Gallium nitride diodes are used specifically for blue light emission where long lifetime at high luminance is critical, while organic diodes are used for green and red emission where they can achieve the desired performance.
2Duration of action of stationary object
If inorganic gallium nitride light-emitting diodes with color conversion elements are used, then long lifetime and high luminance are achieved, but bulk and manufacturing cost increase
Solution Approach 1:
Instead of using color conversion elements on all pixels, the device segments the pixel array into three types with different emission mechanisms. This eliminates the need for bulk color conversion layers and associated manufacturing complexity while maintaining long lifetime through the use of gallium nitride diodes where needed.
3Device complexity
If a monolithic structure with integrated control circuit is used, then device complexity is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The control circuit is merged with the pixel array into a single monolithic structure where the control circuit is formed in the same semiconductor substrate as the pixel diodes. This integration reduces the number of separate components and interconnections, simplifying the overall device structure despite the precision required in the manufacturing process.
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 solution enables a color image display device with improved longevity and reduced manufacturing costs by co-integrating inorganic and organic light-emitting diodes, achieving efficient light emission across multiple wavelength ranges while minimizing bulk and cost constraints.
Implementation Method 1
Each of the first pixels comprises a gallium nitride light-emitting diode
Implementation Method 2
capable of emitting light in a first wavelength range
Implementation Method 3
Each of the second pixels comprises an organic light-emitting diode
Implementation Method 4
capable of emitting light in a second wavelength range
Implementation Method 5
the red and green pixel diodes are then coated with color conversion elements, for example, made up of phosphorus, capable of converting into red light or into green light the blue light emitted by the diodes
Data Source
AI summary
A monolithic display device including a plurality of first pixels capable of emitting light in a first wavelength range, and a plurality of second pixels capable of emitting light in a second wavelength range, the first pixels each including a gallium nitride light-emitting diode, and the second pixels each including an organic light-emitting diode.