Reflective Metal Electrode Structure for OLED Light Extraction
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Solution Overview
Problem
Organic light emitting display devices face reduced light emission efficiency due to the presence of polarizers, which obstruct light emission, especially in high-resolution applications like head-mounted displays, where external light reflectivity is a significant concern.
Innovation Solution
The display device incorporates a light absorption portion within the electrode structure, utilizing reflective metals and auxiliary electrodes to reflect and re-reflect light, eliminating the need for polarizers and enhancing light emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a polarizer is arranged above or below the light emitting layer to prevent external light reflection, then external light reflectivity is reduced, but light emission efficiency is deteriorated
Solution Approach 1:
The first electrode is segmented into multiple sub-electrodes (first sub-electrode, second sub-electrode, etc.), and the light absorption portion is divided into multiple regions corresponding to different sub-pixels. This segmentation allows selective light absorption in specific areas while maintaining light emission in other areas, resolving the contradiction between reducing external light reflection and maintaining light emission efficiency
Solution Approach 2:
The light absorption portion is selectively formed only in specific regions (e.g., in the first sub-electrode corresponding to a first sub-pixel) rather than uniformly across the entire electrode. This local application of light absorption properties allows the device to reduce external light reflection where needed while preserving light emission efficiency in other areas
2Object-affected harmful factors
If a polarizer is used to reduce external light reflectivity, then external light interference is minimized, but the device complexity increases
Solution Approach 1:
The light absorption portion is merged with the first electrode structure, forming an integrated component rather than a separate polarizer layer. This merging eliminates the need for additional polarizer materials and simplifies the overall device structure while still achieving the function of reducing external light reflection
Solution Approach 2:
The first electrode serves multiple functions: it provides electrical connection, emits light, and through the integrated light absorption portion, reduces external light reflection. This multi-functionality eliminates the need for separate polarizer components, reducing device complexity
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 improves light emission efficiency by reducing external light reflectivity and maintaining high resolution, achieving efficiencies comparable to or exceeding those without polarizers while minimizing external light interference.
Implementation Method 1
light emitted from the organic light emitting layer is reflected and re-reflected through the reflective metal and the second electrode
Implementation Method 2
a light absorption portion arranged inside the first electrode
Implementation Method 3
a light emitting layer is formed between an anode electrode and a cathode electrode, and is a device for displaying an image by allowing a light emitting layer to emit light by an electric field between the two electrodes
Data Source
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AI summary
A display device (1) comprises a substrate provided with a first subpixel (21) and a second subpixel (22), a first electrode (5) provided on the substrate, including a first sub electrode (51) provided on the first subpixel (21) and a second sub electrode (52) provided on the second subpixel (22), an organic light emitting layer (10) arranged on the first electrode (5), a second electrode (11) arranged on the organic light emitting layer (10), a first bank (6) provided between the first sub electrode (51) and the second sub (52) electrode to partition the first subpixel (21) and the second subpixel (22) from each other, and a light absorption portion (9) arranged inside each of the first sub electrode (51) and the second sub electrode (52) to absorb external light, wherein the first sub electrode (51) includes a reflective metal (512) provided to cover the light absorption portion (9), and the reflective metal (512) and the second electrode (11) emit light emitted from the organic light emitting layer (10) to the substrate by reflecting the light. Therefore, external light reflectivity may be lowered, and light is reflected and re-reflected through the reflective metal (512) and the second metal, which are arranged at both sides of the organic light emitting layer (10), whereby light emitting efficiency may be more improved than the case that a polarizer is provided.