In-Display Fingerprint Electrode Recess for Flat Photosensitive Layer
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Solution Overview
Problem
The existing in-display fingerprint recognition technology using an LTPS panel and amorphous silicon PIN device suffers from poor flatness due to complex circuit structures and numerous wires, leading to increased dark current and noise, resulting in a low fingerprint recognition rate.
Innovation Solution
A display substrate design with a fingerprint recognition device featuring a first electrode forming a recess in a via hole filled with insulating material, ensuring a flat surface for the photosensitive layer, and additional protective and planarization layers to enhance adhesion and conductivity, while maintaining the original area and aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex circuit structures and numerous wires are used in LTPS panel with amorphous silicon PIN device, then the fingerprint recognition function can be implemented, but the flatness deteriorates leading to increased dark current and noise
Solution Approach 1:
The via hole structure is segmented into multiple components: the via hole itself, the recess formed within it, and the insulating material filling the recess. This segmentation allows each component to be optimized independently - the via hole provides electrical connection, the recess provides flatness, and the insulating material fills the gap to maintain structural integrity
Solution Approach 2:
The insulating material is selectively placed only in the recess area of the via hole, providing local flatness enhancement exactly where needed for the photosensitive layer, without affecting other areas of the device structure
2Manufacturing precision
If the via hole is filled with insulating material to improve flatness, then dark current and noise are reduced, but the electrical connection through the via hole must be maintained
Solution Approach 1:
The recess is formed within the via hole structure before the insulating material is filled. This preliminary action ensures that the electrical connection path is established first, then the insulating material is added to provide flatness without interfering with the already-formed electrical connection
3Device complexity
If the photosensitive layer is disposed on a non-flat surface, then the device structure is simpler, but the dark current increases and fingerprint recognition accuracy decreases
Solution Approach 1:
The insulating material acts as an intermediary between the via hole structure and the photosensitive layer. It provides a flat intermediate surface that allows the photosensitive layer to be disposed uniformly, improving fingerprint recognition accuracy while maintaining the overall device 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 solution significantly reduces dark current and improves the signal-to-noise ratio, enhancing fingerprint recognition accuracy and maintaining the original pixel aperture ratio, thus addressing the issues of noise and low recognition rates caused by non-flatness.
Implementation Method 1
the photosensitive layer is disposed on the flat surface
Data Source
AI summary
A display substrate includes: a base substrate, a drive circuit on the base substrate, an insulating layer on a side of the drive circuit away from the base substrate, and a fingerprint recognition device on a side of the insulating layer away from the base substrate. The fingerprint recognition device includes: a first electrode, a photosensitive layer and a second electrode that are disposed in a stacked manner. The first electrode electrically connects to the drive circuit through a via hole running through the insulating layer; and the first electrode forms a recess in the via hole, and the recess is filled with an insulating material, so that a surface of the first electrode on a side away from the base substrate is a flat surface, and the photosensitive layer is disposed on the flat surface.