Transparent OLED Asymmetric Electrodes Directional Light
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Solution Overview
Problem
Transparent organic light-emitting diodes (OLEDs) face significant light loss due to equal light emission on both sides, reducing their effectiveness as illumination or display elements, and existing solutions are either complex, costly, or compromise on transmittance and efficiency.
Innovation Solution
A transparent light-emitting component with a transparent layer arrangement featuring planar electrodes and an organic region, where one electrode has a metal layer less than 40 nm thick and the other an oxide layer made from conductive oxide material, optimizing light emission and transmittance by adjusting the intensity ratio and using doped charge carrier transport layers to enhance light coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If transparent OLEDs emit light equally in both directions, then the light distribution is symmetric, but approximately 50% of the emitted light is lost which reduces illumination effectiveness
Solution Approach 1:
The patent applies asymmetry by configuring the two electrodes differently: one electrode uses a transparent conductive oxide layer (e.g., ITO, IZO) while the other uses a reflective metal layer (e.g., Al, Ag, Mo). This asymmetric electrode configuration causes the light-emitting organic region to emit light preferentially in one direction through the transparent electrode, while the metal electrode reflects light back through the same side, achieving directional light emission and reducing light loss from 50% to approximately 25% or less
2Ease of operation
If switchable mirrors are combined with transparent OLEDs to transmit all light in one direction, then light directionality is achieved, but the system becomes very complicated and cost-intensive
Solution Approach 1:
The patent extracts and eliminates the need for complex switchable mirror systems by using a simple asymmetric electrode configuration. The directional light emission is achieved inherently through the different optical properties of the transparent oxide electrode and the reflective metal electrode, without requiring additional switching mechanisms or complex optical components
3Illumination intensity
If semitransparent OLEDs use a highly transparent electrode and a less transparent electrode to achieve unequal light emission, then more light is emitted by the highly transparent electrode, but absorption losses in the less transparent electrode reduce overall efficiency and transmittance
Solution Approach 1:
The patent converts the potentially harmful absorption losses into a beneficial effect by using the reflective metal electrode to reflect light back through the transparent electrode. Instead of absorbing light and losing energy, the metal electrode reflects it, turning what would be a loss into additional useful light output in the desired direction, thereby improving both illumination intensity and overall energy 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 achieves high total transparency and improved light utilization, allowing for efficient emission in one direction while maintaining high transmittance, enhancing the component's effectiveness as illumination or display elements.
Implementation Method 1
one of the planar electrodes has a metal layer having a thickness of less than 40 nm, and another of the planar electrodes, which is arranged opposite to the electrode in the transparent layer arrangement, has an oxide layer made from an electrically conductive oxide material having a thickness of at least 10 nm, an intensity ratio of at least 2:1 being formed for a light emission emerging on one side of the transparent layer arrangement and a light emission emerging on an opposite side of the transparent layer arrangement
Data Source
AI summary
The invention relates to a transparent light-emitting component, in particular organic light-emitting diode, having a transparent layer arrangement in which are formed, on a substrate in a stack, planar electrodes and an organic region arranged between the planar electrodes, which organic region comprises a light-emitting layer, made from one or a plurality of organic materials. For at least one direction of incidence, a transmittance of the transparent layer arrangement for at least one wavelength subrange in the visible spectral range is greater than 50%. One of the planar electrodes has a metal layer having a thickness of less than 40 nm, and another of the planar electrodes, which is arranged opposite to the electrode in the layer arrangement, has an oxide layer made from an electrically conductive oxide material having a thickness of at least 10 nm, an intensity ratio of at least 2:1 being formed for a light emission emerging on one side of the transparent layer arrangement and a light emission emerging on an opposite side of the transparent layer arrangement.