Organic Photodiode Detection Device with Buffer Layers and Reverse Bias
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Solution Overview
Problem
Optical biometric sensors, particularly those using organic photodiodes, face issues with detection accuracy and imaging characteristics due to defects in the organic semiconductor layer or conductive layer caused by foreign matter or external scars, leading to spot-like irregularities that degrade performance.
Innovation Solution
A detection device is designed with a plurality of organic photodiodes, capacitive elements, an analog front-end circuit, a power supply circuit, and a control circuit. The organic photodiodes include an active layer with upper and lower buffer layers, and the device applies a reverse bias using a power supply potential controlled by the control circuit to improve detection accuracy and reduce spot irregularities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If organic photodiodes are used for biometric detection, then the device can achieve optical detection functionality, but defects in the organic semiconductor layer or conductive layer cause spot-like irregularities that degrade detection accuracy and imaging characteristics
Solution Approach 1:
The patent applies reverse bias voltage to the organic photodiodes by connecting them in reverse parallel to a capacitor and applying a negative voltage through the AFE circuit. This parameter change (applying reverse bias) modifies the electrical characteristics of the organic photodiodes to reduce the impact of defects in the organic semiconductor layer and conductive layer, thereby reducing spot-like irregularities and improving both detection accuracy and imaging characteristics
Solution Approach 2:
The patent introduces a capacitor as an intermediary element connected in parallel to each organic photodiode. The capacitor serves as a mediator that, when combined with reverse bias voltage application, helps to stabilize the electrical characteristics and reduce the effect of defects in the organic layers,ไป่ reducing spot irregularities and improving detection performance
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 enhances detection accuracy and imaging characteristics by reducing spot irregularities caused by defects, thereby improving the overall performance of the biometric detection system.
Implementation Method 1
Each of the photoelectric conversion elements outputs a signal that changes depending on the amount of light emitted thereto
Implementation Method 2
a power supply circuit configured to supply a power supply potential to collectively apply a reverse bias to the organic photodiodes
Data Source
AI summary
According to an aspect, a detection device includes: a plurality of organic photodiodes arranged in a detection area; a plurality of capacitive elements each coupled in parallel to a corresponding organic photodiode of the organic photodiodes; an analog front-end (AFE) circuit configured to read an electric charge amount stored in each of the capacitive elements to acquire a detection value of each of the organic photodiodes; a power supply circuit configured to supply a power supply potential to collectively apply a reverse bias to the organic photodiodes; and a control circuit configured to control the power supply potential. The organic photodiodes each includes: an active layer; an upper electrode provided with an upper buffer layer interposed between the upper electrode and the active layer; and a lower electrode provided with a lower buffer layer interposed between the lower electrode and the active layer.