Segmented Photodiode Electrode Layout for Lower Leakage Current
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Solution Overview
Problem
Current photodiodes in in-screen fingerprint recognition systems experience high leakage currents when a reverse bias voltage is applied, leading to decreased accuracy of fingerprint information due to defects in the thin film and electrode mismatch, which increases exponentially with voltage.
Innovation Solution
A photodiode design with a substrate, a first electrode comprising sub-parts, a connecting part, an electron transport layer, a light converting part, a hole transport layer, and a second electrode, where the connecting part increases the series resistance, reducing leakage currents and enhancing fingerprint signal accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reverse bias voltage is applied to the photodiode, then the photoelectric conversion capability is improved, but the leakage current increases exponentially
Solution Approach 1:
The first electrode is divided into a first sub-part and a second sub-part disposed at an interval, with a gap between them. This segmentation increases the series resistance of the photodiode, which effectively suppresses the leakage current that flows through the electrode structure, thereby reducing the harmful leakage current while maintaining the photoelectric conversion capability under reverse bias voltage
Solution Approach 2:
A connecting part is introduced to connect the first sub-part and the second sub-part of the first electrode across the gap. This connecting part acts as an intermediary element that provides a controlled electrical path with increased resistance, allowing the structure to maintain electrical functionality while introducing sufficient series resistance to suppress leakage current through the thin film defects and electrode mismatch
2Reliability
If the reverse bias voltage is increased to improve signal detection, then the leakage current increases exponentially
Solution Approach 1:
By segmenting the first electrode into two sub-parts with a gap between them, the patent increases the series resistance path for current flow. This segmentation creates a structural barrier that reduces leakage current through defects in the thin film and mismatch at electrode interfaces, allowing the photodiode to operate reliably at higher reverse bias voltages without excessive energy loss to leakage
3Ease of manufacture
If the photodiode structure is simplified, then the manufacturing cost is reduced, but the leakage current suppression capability is weakened
Solution Approach 1:
The electrode segmentation into first and second sub-parts can be achieved through standard photolithography patterning processes, making it compatible with existing manufacturing workflows. The gap and connecting part can be formed using conventional thin film deposition and patterning techniques, maintaining ease of manufacture while effectively suppressing leakage current through the increased series resistance
Solution Approach 2:
The connecting part is strategically positioned to bridge the gap between the first sub-part and second sub-part of the first electrode. This local structural modification concentrates the resistance-increasing effect at the critical electrode interface region, providing effective leakage current suppression without requiring complex changes to the entire photodiode structure
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 increased series resistance in the photodiode structure effectively reduces leakage currents related to reverse bias voltages, thereby improving the accuracy of fingerprint information captured by the display screen.
Implementation Method 1
photodiodes can convert obtained light signals into current signals
Data Source
AI summary
The present disclosure provides a photodiode, a manufacturing method thereof, and a display screen. The photodiode includes: a first electrode including a first sub-part and a second sub-part disposed at an interval, wherein the second sub-part includes a first end and a second end; a connecting part disposed on the first sub-part, the first end, and a substrate corresponding to a gap between the first sub-part and the second sub-part; and a light converting part and a second electrode disposed on the second end in sequence.