Organic Light Emitting Device Charge Generation Layer Step Structure
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Solution Overview
Problem
Organic light emitting display devices face limitations in luminous efficiency, lifetime, and power consumption, particularly due to light leakage phenomena in tandem structures, which degrade optical reliability by causing undesired light emission from adjacent sub-pixels.
Innovation Solution
An organic light emitting device structure is developed with a charge generation layer disposed between multiple electroluminescence units in each sub-pixel area, featuring thickness differences and steps to prevent lateral current flow, ensuring the charge generation layer does not function as a lateral current path between sub-pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a charge generation layer is applied to the organic light emitting device of tandem structure, then luminous efficiency is improved by connecting multiple light emitting devices in series, but light leakage from an undesired adjacent sub-pixel occurs which decreases optical reliability
Solution Approach 1:
The charge generation layer is designed with spatially varying thickness: thicker in the center region of each sub-pixel to ensure adequate charge generation, and thinner or absent at the boundary regions to prevent lateral current flow. This local variation in layer quality resolves the contradiction by maintaining luminous efficiency through sufficient charge generation while preventing light leakage through reduced lateral conductivity at boundaries.
Solution Approach 2:
The charge generation layer is segmented into distinct regions: a central charge generation region and boundary regions with reduced or zero thickness. This segmentation creates electrical isolation between adjacent sub-pixels at their interfaces, preventing lateral current flow that causes light leakage, while maintaining functional charge generation in the central regions for improved luminous efficiency.
2Use of energy by moving object
If multiple electroluminescence units are stacked to improve luminous efficiency, then power consumption is reduced, but light leakage phenomenon increases which degrades optical reliability
Solution Approach 1:
The charge generation layer exhibits local quality variation with different thickness characteristics in different spatial regions. The thicker central portions enable effective charge generation across multiple stacked electroluminescence units, reducing power consumption, while the thinner or absent boundary portions prevent lateral current leakage, maintaining optical reliability.
Solution Approach 2:
The thickness parameter of the charge generation layer is changed spatially across the device structure. By varying the thickness from center to boundary regions, the invention achieves both low power consumption through effective vertical charge generation and high optical reliability through suppressed lateral current flow at boundaries.
3Loss of energy
If the charge generation layer is made continuous to ensure charge generation, then luminous efficiency improves, but lateral current flow between sub-pixels increases causing light leakage
Solution Approach 1:
The charge generation layer transitions from a uniform continuous structure to a non-uniform structure with locally varying thickness. The central regions maintain sufficient thickness for effective charge generation, while boundary regions have reduced thickness to eliminate lateral current pathways, thus resolving the contradiction between luminous efficiency and preventing harmful lateral current flow.
Solution Approach 2:
The charge generation layer is segmented into functionally distinct zones: continuous thick regions for charge generation and discontinuous thin/absent regions at boundaries for current isolation. This segmentation eliminates lateral current flow between sub-pixels while preserving vertical charge generation functionality for improved luminous efficiency.
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 configuration effectively minimizes lateral current and prevents light leakage, thereby enhancing the optical reliability of organic light emitting display devices by ensuring that only intended sub-pixels emit light, improving luminous efficiency and extending the device's lifespan while reducing power consumption.
Implementation Method 1
An organic light emitting device emits light when electrons and holes are injected into an emission layer from a cathode used for injecting electrons and an anode used for injecting holes. As excitons are formed from the combination of the injected electron and hole transitions, it produces an organic light emitting device when it moves from an excited state to a ground state.
Data Source
AI summary
Provided is an organic light emitting device including: an organic emission layer disposed between a first electrode and a second electrode and in a plurality of sub-pixel areas; a plurality of electroluminescence units which include the organic emission layer and are formed by stacking; and a charge generation layer between the plurality of electroluminescence units, where the charge generation layers respectively disposed in the plurality of sub-pixel areas have a step and are formed at different positions, and the second electrodes respectively disposed in the multiple sub-pixel areas have a step and are formed at different positions.