OLED Pixel Bank Structure for White Purity and Process Simplification
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Solution Overview
Problem
Conventional organic electroluminescence display devices face challenges in achieving high brightness and color purity due to the complexity of forming separate organic electroluminescence films for red, green, blue, and white light emission, which results in decreased light extracting efficiency and difficulty in color balance adjustment.
Innovation Solution
The solution involves stacking multiple organic electroluminescence layers on an insulating substrate, with a white light-emitting pixel formed simultaneously with color pixels, using a multilayered film structure where the white pixel has a larger thickness and specific bank arrangements to allow for easy color purity adjustment without increasing the number of formation processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate organic electroluminescence films for red, green, blue and white light emission are formed, then full color display capability is achieved, but the number of formation processes increases and manufacturing complexity increases
Solution Approach 1:
The patent merges the formation of white light-emitting organic electroluminescence films with color pixels by stacking white light-emitting layers on top of color light-emitting layers in the same pixel structure. This allows simultaneous formation of both white and color emission capabilities through a unified multi-layer organic electroluminescence film structure, reducing the number of separate formation processes while achieving full color display capability.
2Adaptability or versatility
If separate organic electroluminescence films for red, green, blue and white light emission are formed, then full color display capability is achieved, but light extracting efficiency decreases
Solution Approach 1:
The patent transitions from a single-layer to a multi-layer vertical structure within the same pixel area. By stacking white light-emitting layers above color light-emitting layers in the vertical dimension, the patent enables both white and color emission without increasing horizontal pixel density or reducing individual pixel area, thereby maintaining light extracting efficiency while achieving full color capability.
3Adaptability or versatility
If separate organic electroluminescence films for red, green, blue and white light emission are formed, then full color display capability is achieved, but color balance adjustment becomes difficult
Solution Approach 1:
The patent applies local quality by allowing different organic electroluminescence layers (white and color) to have distinct material compositions and emission characteristics tailored to their specific functions. Each layer can be independently optimized for its color emission properties while maintaining uniform formation processes, enabling precise color balance adjustment through material selection rather than complex process variations.
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 enables high-brightness full-color images with improved white purity and simplified manufacturing by using the same processes for color and white light-emitting layers, enhancing light extraction efficiency and color balance.
Implementation Method 1
By applying an electric field to between the bottom electrode BEL as an anode and the upper electrode UEL as a cathode, carriers (electrons and positive holes) are injected to the organic electroluminescence elements composed of organic multilayer films, and the organic multilayer films emit light.
Data Source
AI summary
The recent invention provide an organic electroluminescence display device with color purity adjustment, particularly white purity increased, without increasing formation processes. For each of unit pixels formed on an insulating film INS formed on a principal surface of a glass substrate, a bank BNK is provided on a bottom electrode BEL being a pixel electrode. The bank BNK has the shape of a bank that surrounds a pixel concerned, for each of pixels, and an organic electroluminescence light emitting layer is charged within a region surrounded by the banks BNKs. Between the banks BNKs, a green light emitting layer (G light emitting layer), a blue light emitting layer (B light emitting layer), and a red light emitting layer (R light emitting layer) are provided. At the same time as the formation of these color light emitting layers, light emitting layers of three colors, the green light emitting layer (G light emitting layer), the blue light emitting layer (B light emitting layer), and the red light emitting layer (R light emitting layer) are stacked on a region of a white pixel to form a white light emitting layer (G+B+R). An upper electrode UEL is formed over the green light emitting layer (G light emitting layer), the blue light emitting layer (B light emitting layer), the red light emitting layer (R light emitting layer), and the white light emitting layer (G+B+R light emitting layer).