LED Optical Cavity with Unpatterned Layers and Spacers
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Solution Overview
Problem
Existing LED devices face inefficiencies in light output and angular color performance due to trapped light and manufacturing complexities, particularly in large-scale production and ambient illumination conditions.
Innovation Solution
A light-emitting diode device structure featuring a substrate, a reflective electrode, an unpatterned light-emitting layer, a transparent electrode, and optical spacers with different path lengths between the electrodes, along with a low-index layer, which employs Fresnel reflections and unpatterned materials to enhance light output and reduce angular color change.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If optical cavity structures with patterned organic materials are used, then light output is improved, but manufacturing complexity increases and scalability to large substrates becomes difficult
Solution Approach 1:
The device is divided into distinct functional layers including a substrate, reflective electrode, unpatterned light-emitting layer, transparent electrode, and optical spacers. This segmentation allows each layer to be optimized independently, simplifying manufacturing while maintaining light output enhancement through the optical cavity effect.
Solution Approach 2:
Instead of patterning the light-emitting organic materials as in conventional approaches, this invention uses an unpatterned light-emitting layer combined with optical spacers to define the optical cavity regions. This inversion of the conventional approach simplifies the deposition process and improves scalability to large substrates.
2Ease of manufacture
If conventional LED structures are used, then manufacturing is simpler, but more than 50% of emitted light is trapped due to total internal reflection
Solution Approach 1:
Optical spacers are introduced as intermediary elements between the reflective electrode and transparent electrode. These spacers create optical cavities that modify the optical path and enable extraction of trapped light through interference effects, while maintaining manufacturing simplicity through a layered structure that can be deposited using conventional techniques.
Solution Approach 2:
The optical path length within the device is modified by introducing optical spacers with specific thicknesses. This parameter change creates constructive and destructive interference patterns that enhance light extraction efficiency, allowing more light to escape the high-optical-index emissive materials without complicating the manufacturing process.
3Illumination intensity
If optical cavity structures are used, then light output is enhanced, but angular color dependence becomes unacceptable
Solution Approach 1:
The optical cavity structure with unpatterned light-emitting layer serves multiple functions: it enhances light output through the optical resonance effect while simultaneously providing angular color stability. The optical spacers create a universal optical path that maintains consistent color characteristics across different viewing angles, unlike conventional patterned approaches.
4Object-affected harmful factors
If color filters are used with optical cavity, then ambient contrast ratio improves, but device efficiency decreases due to light absorption
Solution Approach 1:
Color filters are extracted from the device structure and replaced by the unpatterned light-emitting layer combined with optical spacers. This extraction eliminates the light-absorbing color filter layer while maintaining the ability to control emitted light characteristics through the optical cavity effect, thereby preserving device 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 solution increases light output and minimizes angular color change, improving the efficiency and manufacturability of LED devices while maintaining a consistent color appearance across various viewing angles.
Implementation Method 1
optical spacers with different path lengths, which employ Fresnel reflections and unpatterned materials to enhance light output
Implementation Method 2
a reflective electrode formed over the substrate
Implementation Method 3
a low-index layer formed over the transparent electrode
Data Source
AI summary
A light-emitting optical cavity light-emitting diode device, comprising:a) a substrate;b) a reflective electrode formed over the substrate;c) an unpatterned light-emitting layer formed over the reflective electrode;d) a transparent electrode formed over the unpatterned light-emitting layer;e) one or more different optical spacers, defining at least two different optical path lengths, are formed in different locations over the substrate, between the reflective electrode and the transparent electrode; andf) a low-index layer formed over the transparent electrode.