Anisotropic OLED Emitter Orientation for Light Outcoupling
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Solution Overview
Problem
Conventional organic light-emitting diodes (OLEDs) suffer from low light outcoupling efficiency, with only about a quarter of generated light being emitted into the environment, while the rest is lost through wave guidance in the substrate, transparent electrode, and surface plasmons, and existing solutions to enhance outcoupling either limit efficiency or affect the appearance of the OLED.
Innovation Solution
An organic light-emitting device with a translucent electrode and a reflective electrode, featuring anisotropic emitter molecules oriented parallel to the organic light-emitting layers, and an optical outcoupling layer with a high refractive index to enhance light outcoupling by reducing plasmon losses and increasing radiant power emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If scattering films or surface patterns are applied to increase light outcoupling, then light outcoupling efficiency is improved, but the appearance of the OLED is affected substantially with a milky, diffusely reflective surface
Solution Approach 1:
The patent applies local quality by creating patterned regions with different refractive indices at specific locations (under the transparent electrode) rather than uniformly modifying the entire surface. This localized approach allows light outcoupling enhancement in specific areas while preserving the overall visual appearance of the OLED surface.
Solution Approach 2:
The patent changes the refractive index parameter by introducing regions with refractive index n < 1.35 (low-index regions) and n > 1.65 (high-index regions) under the transparent electrode. This parameter modification enables control over light propagation and outcoupling efficiency without affecting the surface appearance, as the changes occur in the bulk material properties rather than surface morphology.
2Ease of manufacture
If conventional OLED structure is used, then manufacturing is simple, but only around 25% of generated light is outcoupled into the surrounding environment
Solution Approach 1:
The patent employs composite materials by combining regions with different refractive indices (n < 1.35 and n > 1.65) within the organic layers or under the transparent electrode. This composite structure leverages the optical properties of different materials to enhance light outcoupling efficiency while maintaining compatibility with existing OLED manufacturing processes.
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 significantly increases light outcoupling efficiency by suppressing plasmon excitations and guiding more light out of the device, resulting in improved radiant power emission compared to conventional OLEDs.
Implementation Method 1
an optical outcoupling layer with a high refractive index to enhance light outcoupling
Implementation Method 2
around 30% through the generation of surface plasmons in a metallic electrode
Implementation Method 3
anisotropic emitter molecules oriented parallel to the organic light-emitting layers
Implementation Method 4
The wave guidance effects arise in particular through the refractive index differences at the interfaces between the individual layers and regions of an OLED
Implementation Method 5
The further electrode may particularly preferably be of reflective construction
Data Source
AI summary
An organic light-emitting component is specified, comprising a translucent substrate (1), on which a translucent electrode (3) is arranged, comprising on the translucent electrode (3) an organic functional layer stack comprising organic functional layers having at least one organic light-emitting layer (5) and comprising a further electrode (7), wherein the at least one organic light-emitting layer (5) comprises emitter molecules having an anisotropic molecular structure which are oriented anisotropically, and wherein all the organic light-emitting layers (5, 51, 52, 53) of the organic light-emitting component are at a distance of greater than or equal to 20 nm and less than or equal to 100 nm from the further electrode (7).