OLED First Electrode Thickness Variation for Light Sensing
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Solution Overview
Problem
External light interference complicates accurate light measurement in organic light-emitting displays (OLEDs), affecting the sensitivity of optical sensors and the ability to maintain constant visibility in portable displays.
Innovation Solution
The design includes a first electrode with a thinner region overlapping a photodiode and a thicker region, acting as a reflective electrode to suppress external light interference, ensuring more light from the organic layer reaches the photodiode for improved sensing capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniform thickness first electrode is used, then the manufacturing process is simple, but external light interferes with the photodiode sensing capability
Solution Approach 1:
The first electrode is designed with different thicknesses in different regions: a first region with a first thickness and a second region with a second thickness greater than the first thickness. This local variation in thickness provides different optical characteristics (transparency vs. reflectivity) in different areas, allowing the electrode to simultaneously achieve light transmission to the photodiode and external light shielding, thereby resolving the contradiction between sensing capability and external light interference without requiring a completely different electrode structure.
2Measurement precision
If the first electrode is made thinner to allow more light to reach the photodiode, then sensing capability improves, but external light interference increases
Solution Approach 1:
The first electrode employs local quality variation with a thinner first region for light transmission and a thicker second region for external light blocking. This spatial differentiation allows the same electrode structure to perform dual functions: enabling accurate light measurement by the photodiode while simultaneously protecting it from external light interference, thus resolving the contradiction between measurement precision and harmful external light factors.
Solution Approach 2:
The first electrode is segmented into functionally distinct regions: a first region with lower thickness for optical transmission and a second region with higher thickness for optical shielding. This segmentation allows each region to optimize its performance for its specific function, with the thinner region maximizing light transmission to the photodiode and the thicker region maximizing external light rejection, thereby resolving the contradiction between measurement accuracy and external light interference.
3Object-affected harmful factors
If a thicker first electrode is used to block external light, then external light interference is reduced, but less light from the organic layer reaches the photodiode
Solution Approach 1:
The first electrode uses local quality differentiation where the second region has greater thickness for external light blocking while the first region has lesser thickness for light transmission. This resolves the contradiction between external light interference reduction and light transmission efficiency by assigning different thickness characteristics to different functional regions of the same electrode, allowing both goals to be achieved simultaneously without compromising energy efficiency.
Solution Approach 2:
The electrode is divided into segmented regions with different thicknesses: a thicker second region for shielding against external light and a thinner first region for efficient light transmission from the organic layer to the photodiode. This segmentation enables each region to optimize its thickness for its specific purpose, resolving the contradiction between harmful external light factors and useful light transmission 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 enhances the sensitivity of the optical sensor by reducing external light interference, allowing for more precise light measurement and adjustment, thereby maintaining consistent display visibility.
Implementation Method 1
The first electrode includes a reflective electrode
Implementation Method 2
a photodiode on the substrate... an organic light-emitting diode may include an anode, an organic layer and a cathode, and the sensitivity of the optical sensor is dependent on optical characteristics
Data Source
AI summary
An organic light-emitting display and a method of manufacturing an organic light-emitting display are described. According to an aspect, the organic light-emitting display includes a substrate, a photodiode on the substrate, a planarization layer covering the photodiode, a first electrode on the planarization layer, a pixel defining layer at least partially exposing the first electrode, an organic layer covering the first electrode which is exposed by the pixel defining layer and a second electrode covering the pixel defining layer and the organic layer.