Light-Emitting Element Dipole Orientation Control
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Solution Overview
Problem
Current light-emitting elements, particularly organic EL elements, face limitations in achieving high external quantum efficiency due to low light extraction efficiency, which restricts their performance and efficiency in emitting various colors.
Innovation Solution
A light-emitting element with a specific structure comprising a first and second electrode and an EL layer, where the second substance, such as a phosphorescent or fluorescent substance, is used in a ratio that optimizes light emission directionality, enhancing external quantum efficiency by controlling the orientation of transition dipoles to maximize light extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If light-emitting substances are deposited with aligned orientations to control light emission direction, then light extraction efficiency is improved, but device complexity increases
Solution Approach 1:
The patent changes the orientation parameter of light-emitting substances by controlling the deposition process to achieve aligned orientations. This parameter change enables directional control of light emission and improves light extraction efficiency without requiring additional complex structures
Solution Approach 2:
The patent performs preliminary alignment of light-emitting substance orientations during the deposition process itself. By establishing the desired orientation configuration before device operation, the system achieves improved light extraction without requiring post-deposition alignment mechanisms
2Productivity
If internal quantum efficiency is increased to improve current efficiency, then emission efficiency improves, but light extraction efficiency becomes the limiting factor
Solution Approach 1:
The patent changes the spatial distribution parameter of light emission by aligning transition dipoles in specific orientations. This enables better coupling between the light-emitting layer and external space, improving light extraction efficiency to match the high internal quantum efficiency
Solution Approach 2:
The patent uses composite light-emitting layers containing multiple substances with different emission characteristics. By combining substances with optimized orientations and emission properties, the system achieves both high internal quantum efficiency and high light extraction 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
The optimized light-emitting element achieves external quantum efficiencies of 25% or higher, significantly improving emission efficiency and enabling low power consumption in display and lighting devices.
Implementation Method 1
the use of different types of light-emitting substances makes it possible to obtain light-emitting elements which exhibit various colors
Implementation Method 2
by utilizing a triplet excited state, some light-emitting elements that emit fluorescence have achieved an internal quantum efficiency of 25%
Implementation Method 3
depositing light-emitting substances such that their orientations are aligned with each other to control the direction of light emission
Data Source
AI summary
A light-emitting element is provided. The light-emitting element includes first and second electrodes and an EL layer therebetween. The EL layer includes a light-emitting layer containing first and second substances. The amount of the first substance is larger than that of the second substance. The second substance emits light. Average transition dipole moments of the second substance are divided into three components in x-, y-, and z-directions which are orthogonal to each other. Components parallel to the first or second electrode are assumed to be the components in the x- and y-directions, and a component perpendicular to the first or second electrode is assumed to be the component in the z-direction. The proportion of the component in the z-direction is represented by a, which is less than or equal to 0.2.