Organic Microcavity Pixel Array Optical Thickness Control
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Solution Overview
Problem
Integration of color pixels of three primary colors onto a single substrate in organic light emitting devices with microcavity structures presents challenges, particularly with ink-jet printing techniques, due to the need for precise control of optical thickness and reflectivity to achieve full color displays.
Innovation Solution
A multi-color display is achieved by using a pixel array with an organic active layer and a transparent conducting layer, where sub-pixels within individual pixels have different optical thicknesses and interface reflectivities, allowing for selective emission of narrowed spectral bands to produce a range of colors, utilizing a Distributed Bragg Reflector and electrodes with semi-transparent metallic layers to enhance color purity and brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single organic active layer material is used for all sub-pixels, then manufacturing simplicity is maintained, but color differentiation across sub-pixels cannot be achieved
Solution Approach 1:
The patent applies local quality by varying the optical thickness of the transparent conducting layer at different sub-pixel locations while maintaining a uniform organic active layer. This allows each sub-pixel to have different optical characteristics (color) without requiring different active layer materials, thus achieving color differentiation while maintaining manufacturing simplicity. The optical thickness variation is achieved through controlled deposition processes that create location-specific thickness profiles.
Solution Approach 2:
The patent changes the optical parameter (thickness) of the transparent conducting layer to achieve different colors in different sub-pixels. By controlling the thickness parameter of this layer, the optical path length and interference conditions are modified locally, enabling color differentiation. This parameter-based approach allows a single organic active layer to produce multiple colors through optical engineering rather than material differentiation.
2Manufacturing precision
If microcavity structures with precise optical thickness control are implemented, then color purity is improved, but manufacturing complexity increases
Solution Approach 1:
The transparent conducting layer serves multiple functions simultaneously: it acts as an electrode for electrical contact, provides optical transparency for light extraction, and functions as an optical cavity element through its controlled thickness. This multi-functionality reduces the need for separate components, thereby managing manufacturing complexity while achieving the microcavity effect necessary for high color purity.
Solution Approach 2:
The patent employs dynamic control of the transparent conducting layer thickness during the manufacturing process, allowing precise adjustment of optical properties. By making the thickness a controllable variable rather than a fixed parameter, the system can be optimized for color purity while using standard manufacturing techniques, thus balancing precision requirements with manufacturing feasibility.
3Adaptability or versatility
If different optical thicknesses are used for different sub-pixels, then full color display capability is achieved, but control precision requirements increase
Solution Approach 1:
The patent performs preliminary action by pre-calculating and pre-setting the required thickness profile of the transparent conducting layer during the design and manufacturing planning stage. This allows the complex thickness distribution to be established in a single deposition process rather than requiring multiple adjustment steps, thereby reducing the precision demands on real-time control while still achieving the necessary optical thickness variations for full color display.
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 high color purity and high brightness full-color displays with improved manufacturing efficiency and cost-effectiveness, capable of achieving color coordinates comparable to commercial HDTV standards with high pixel density.
Implementation Method 1
an organic active layer including a material that emits a first spectral distribution of visible light having a first color; one or more pairs of electrodes for selectively energizing sub-pixel areas of the organic active layer to generate an emission of visible light
Implementation Method 2
different sub-pixels within individual pixels of the array have different optical thicknesses based at least on the corresponding sub-pixel portions of said transparent conducting layer having different optical thicknesses, and wherein at least one sub-pixel within an individual pixel of said array has a selected color different from said first color due to at least one narrowed spectral band being selected out of said first spectral distribution
Implementation Method 3
interface reflectivities are present wherein at least one narrowed spectral band is selected within said first spectral distribution by outcoupling emitted light through at least one corresponding sub-pixel area
Data Source
AI summary
A multi-color pixel array and method includes an organic active layer of a material emitting a first spectral distribution of visible light having a first color; a transparent conducting layer, each of which include portions that correspond to individual pixels and sub-pixels of the array; one or more pairs of electrodes for selectively energizing sub-pixel areas of the organic active layer to generate an emission of visible light of a first spectral distribution; wherein different sub-pixels within individual pixels of the array have different optical thicknesses based at least on corresponding sub-pixel portions of the transparent conducting layer having different optical thicknesses; and wherein at least one sub-pixel of has a selected color different from the first color due to at least one narrowed spectral band being selected out of the first spectral distribution as emitted light is coupled out of the display through the transparent conducting layer.