Organic Photodiode Edge Light Blocking for Accurate Biometrics
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Solution Overview
Problem
Optical sensors using organic photodiodes (OPDs) require higher detection accuracy to enhance their performance in fingerprint and vein pattern detection.
Innovation Solution
A detection device with a substrate and photodiodes stacked in layers, including a light-blocking layer in the edge regions of the lower and upper buffer layers and electrodes, to improve detection accuracy by reducing delayed carrier response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical sensors use organic photodiodes with standard structure, then device complexity is reduced, but detection accuracy deteriorates due to delayed carrier response in edge regions
Solution Approach 1:
The photodiode active region is segmented into a central region and edge regions, with the light-blocking layer selectively positioned only in the edge regions. This segmentation allows different parts of the photodiode to have different functions: the central region maintains full light detection capability while the edge regions are protected from delayed carrier generation, thus improving detection accuracy without requiring complete structural redesign of the entire photodiode.
Solution Approach 2:
The light-blocking layer is applied locally only to the edge regions of the photodiode where delayed carrier generation occurs, rather than covering the entire photodiode structure. This local application of the light-blocking layer selectively eliminates the harmful effect in the problematic areas while preserving the light-detecting function in the central region, achieving improved detection accuracy with minimal added complexity.
2Measurement precision
If light-blocking layer is added to eliminate delayed carrier response, then detection accuracy is improved, but manufacturing complexity increases
Solution Approach 1:
The light-blocking layer is merged with the existing photodiode structure by positioning it directly on the substrate beneath the lower electrode in the edge regions. This integration approach combines the light-blocking function with the existing device architecture, avoiding the need for separate, complex manufacturing steps and reducing overall manufacturing complexity while still achieving the desired detection accuracy improvement.
3Measurement precision
If light-blocking layer covers entire photodiode, then delayed carrier response is eliminated, but light detection efficiency decreases
Solution Approach 1:
The photodiode area is segmented into central and edge regions, with the light-blocking layer applied only to the edge regions. This segmentation ensures that the light-blocking function is applied selectively where delayed carrier generation occurs, while the central region maintains full light detection capability, thus preserving overall light detection efficiency while improving detection accuracy.
Solution Approach 2:
The light-blocking layer is applied locally only to edge regions where delayed carrier generation is problematic, rather than covering the entire photodiode. This local application preserves light detection efficiency in the central region while eliminating delayed carrier response in the edge regions, achieving the optimal balance between detection accuracy and light detection 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 configuration enhances detection accuracy by minimizing the impact of delayed carrier generation in edge regions, leading to improved fingerprint and vein pattern recognition.
Implementation Method 1
optical sensors that include a plurality of photodiodes (organic photodiodes (OPDs)) each using an organic semiconductor material as an active layer
Data Source
AI summary
According to an aspect, a detection device includes: a substrate; a plurality of photodiodes in each of which a lower electrode, a lower buffer layer, an active layer, an upper buffer layer, and an upper electrode are stacked on the substrate in the order as listed; and a light-blocking layer provided in an area overlapping an edge region of the lower buffer layer, an edge region of the active layer, an edge region of the upper buffer layer, and an edge region of the lower electrode in plan view. The upper electrode covers the lower buffer layer, the active layer, the upper buffer layer, and the lower electrode. The lower buffer layer, the active layer, the upper buffer layer, and the lower electrode are arranged so as to be separated for each of the photodiodes.