Organic Photodiode Detection Using Auxiliary Capacitor Electrodes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Optical sensors face a trade-off between increasing the area of the lower electrode of the photodiode to enhance sensor capacity and reducing leakage current, which affects detection sensitivity.
Innovation Solution
The detection device incorporates a substrate with photodiodes using organic semiconductors, transistors, and auxiliary capacitor electrodes to increase sensor capacity while minimizing leakage current, utilizing a layered configuration of auxiliary capacitor electrodes and insulating films to enhance detection sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the area of the lower electrode of the photodiode is increased, then the sensor capacity is increased, but the leakage current of the photodiode is increased
Solution Approach 1:
The lower electrode is divided into multiple separate lower electrodes arranged in the substrate plane, with each lower electrode having a smaller area. This segmentation reduces the leakage current from each electrode while the collective arrangement maintains sufficient sensor capacity across the photodiode structure.
Solution Approach 2:
The patent transitions from a single large lower electrode to multiple smaller lower electrodes distributed in the substrate plane, utilizing the two-dimensional plane to achieve both reduced leakage current and maintained sensor capacity through spatial distribution.
2Object-generated harmful factors
If the area of the lower electrode of the photodiode is reduced, then the leakage current is reduced, but the sensor capacity is decreased
Solution Approach 1:
The lower electrode is segmented into multiple smaller electrodes distributed across the substrate plane. Each small electrode contributes to the total sensor capacity while individually maintaining low leakage current, achieving a balance between these competing requirements.
Solution Approach 2:
Multiple small lower electrodes are electrically connected and spatially distributed to function as a unified sensing structure. The combined effect of these multiple electrodes provides sufficient sensor capacity while each individual electrode maintains low leakage current characteristics.
3Measurement precision
If the maximum output power of the signal from the photodiode is increased, then the detection sensitivity is improved, but the sensor capacity must be increased which may increase leakage current
Solution Approach 1:
By segmenting the lower electrode into multiple smaller electrodes, the patent enables increased sensor capacity to support higher maximum output power for improved detection sensitivity, while each small electrode maintains low leakage current, thus resolving the contradiction between detection sensitivity and leakage current.
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 improves detection sensitivity by increasing the maximum output signal while reducing leakage current, thereby enhancing the overall performance of the detection device.
Implementation Method 1
Optical sensors capable of detecting fingerprint patterns and vein patterns are known... Each includes a plurality of photodiodes... An electric charge generated when each of the photodiodes is irradiated with light
Implementation Method 2
a first auxiliary capacitor electrode provided between the substrate and each of the photodiodes in the direction orthogonal to the substrate, and a second auxiliary capacitor electrode that is provided in the same layer as that of the semiconductor layer or the source electrode, and faces the first auxiliary capacitor electrode with an insulating film interposed between the first auxiliary capacitor electrode and the second auxiliary capacitor electrode
Data Source
AI summary
A detection device includes a substrate, a plurality of photodiodes that are provided on the substrate, and include organic semiconductors, a plurality of transistors that are provided correspondingly to the respective photodiodes, and each include a semiconductor layer, a gate electrode, and a source electrode, a plurality of lower electrodes that are provided between the transistors and the photodiodes in a direction orthogonal to the substrate, and are provided correspondingly to the respective photodiodes, an upper electrode provided across the photodiodes, a first auxiliary capacitor electrode provided between the substrate and each of the photodiodes in the direction orthogonal to the substrate, and a second auxiliary capacitor electrode that is provided in the same layer as that of the semiconductor layer or the source electrode, and faces the first auxiliary capacitor electrode with an insulating film interposed between the first auxiliary capacitor electrode and the second auxiliary capacitor electrode.