Optical Sensor Electrode Segmentation for Leakage-Resistant Detection
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Solution Overview
Problem
Existing optical sensors, particularly those using organic photodiodes, face challenges in achieving high detection accuracy for fingerprint and vascular pattern recognition.
Innovation Solution
A detection device with a substrate and optical sensors stacked in a specific configuration, featuring first and second lower electrodes separated and surrounded by a continuous buffer and active layer, enhancing detection accuracy through improved carrier response and reduced leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional optical sensor structure with single lower electrode is used, then the device complexity is low, but the detection accuracy and optical sensitivity are insufficient
Solution Approach 1:
The lower electrode is divided into two separate electrodes (first lower electrode and second lower electrode) positioned at different heights. This segmentation allows independent optimization of each electrode's function: the first lower electrode collects carriers from the active layer while the second lower electrode provides shielding and reduces leakage current, thereby improving detection accuracy without requiring complete redesign of the entire sensor system
Solution Approach 2:
The patent introduces a vertical dimension to the electrode structure by stacking the first and second lower electrodes at different heights within the sensor layer. This three-dimensional electrode arrangement enables simultaneous achievement of carrier collection and electrical shielding functions that would be difficult to accomplish with a planar single-electrode design, thus improving optical sensitivity while maintaining manageable device complexity
2Measurement precision
If the lower electrode area is increased to improve carrier collection, then the optical sensitivity improves, but the leakage current between adjacent sensors increases
Solution Approach 1:
By segmenting the lower electrode into two vertically separated electrodes, the patent enables the first lower electrode to have larger area for improved carrier collection while the second lower electrode provides electrical isolation and shielding. This segmentation effectively separates the carrier collection function from the shielding function, allowing optimization of both aspects simultaneously
Solution Approach 2:
The second lower electrode acts as an intermediary shielding layer between adjacent sensor elements. This intermediate structure blocks leakage current paths between neighboring sensors while allowing the first lower electrode to maintain large area for efficient carrier collection, thus reducing harmful leakage effects without sacrificing optical sensitivity
3Ease of manufacture
If the buffer layers and upper electrode are made continuous to simplify manufacturing, then the ease of manufacture improves, but the resolution between adjacent sensors decreases
Solution Approach 1:
The continuous buffer layers and upper electrode are segmented into sensor-specific regions corresponding to each optical sensor element. This segmentation creates electrical isolation between adjacent sensors through the buffer layers, preventing signal crosstalk and improving resolution, while the segmentation pattern follows a regular grid structure that can be manufactured using standard photolithography and deposition techniques, maintaining ease of manufacture
Solution Approach 2:
The buffer layers and upper electrode are designed with local quality variations: they are continuous within each sensor element to ensure proper electrical connection and coverage, but are separated or isolated between adjacent sensor elements to prevent leakage current. This local differentiation allows simultaneous achievement of manufacturing simplicity through continuous deposition processes and high resolution through localized electrical isolation
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 device achieves improved resolution and optical sensitivity, accommodating high-resolution and high-response speed requirements for fingerprint and vascular pattern detection.
Implementation Method 1
an organic photosensitive layer that photoelectrically converts incident light
Data Source
AI summary
According to an aspect, a detection device includes: a substrate; and a plurality of optical sensors formed by stacking first and second lower electrodes, a lower buffer layer, an active layer, an upper buffer layer, and an upper electrode on the substrate in the order as listed. The first lower electrodes are arranged so as to be separated for each of the optical sensors. The second lower electrodes are provided so as to surround the first lower electrodes, respectively. The lower buffer layer, the active layer, the upper buffer layer, and the upper electrode are provided continuously over the optical sensors so as to cover the first and the second lower electrodes.