Segmented Cathode Electrodes for High Transmittance Display Substrates

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Solution Overview

Problem

The transmittance of cathodes in display substrates is typically low, resulting in poor photosensitive effects for sensors, as they cover organic material layers, limiting the screen-to-body ratio in full-screen display devices.

Innovation Solution

A display substrate design with a photosensitive region featuring spaced display regions and a gap region, where the second electrode layer includes second electrodes that do not overlap with the gap region, allowing for improved light transmittance and enhanced photosensitive performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a cathode layer is used to cover the organic material layer, then the display substrate structure is complete and functional, but the light transmittance in the photosensitive region is reduced to approximately 50%, resulting in poor photosensitive effect

Engineering Contradiction:

Improvedisplay substrate structure completenessVSAvoidlight transmittance in photosensitive region

Core Design Contradiction:

ReliabilityVSIllumination intensity

Solution Approach 1:

The cathode layer is segmented into multiple isolated second electrodes corresponding to different display regions, with gap regions between them. This segmentation allows light to pass through the gap regions while maintaining electrical functionality in the display regions, thereby resolving the contradiction between structural completeness and light transmittance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The second electrodes are selectively positioned only in the display regions, while the gap regions remain without cathode coverage. This local differentiation allows the photosensitive region to have high light transmittance where sensors are located, while maintaining proper display functionality in the display regions, thus resolving the contradiction between overall structure and local optical performance.

Inventive Principle:

Principle #3Local quality

2Area of stationary object

If sensors are disposed below the display substrate to increase screen-to-body ratio, then the screen-to-body ratio is effectively increased, but the photosensitive function is degraded due to low transmittance of the cathode layer

Engineering Contradiction:

Improvescreen-to-body ratioVSAvoidphotosensitive function

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

By segmenting the cathode layer into discrete second electrodes with gap regions between them, the structure enables both full-screen display appearance and effective light transmission to underlying sensors, thus resolving the contradiction between screen-to-body ratio and photosensitive function.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The gap regions act as intermediary spaces that allow light to pass through from the display surface to the sensors below, mediating between the need for a complete display structure and the requirement for effective sensor operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If the cathode layer is arranged as a whole layer covering the organic material layer, then the display substrate structure is simplified, but the transmittance of the photosensitive region is low, resulting in poor photosensitive effect

Engineering Contradiction:

Improvecathode layer structureVSAvoidphotosensitive region transmittance

Core Design Contradiction:

Device complexityVSIllumination intensity

Solution Approach 1:

The cathode layer is divided into multiple isolated second electrodes rather than forming a continuous whole layer. This segmentation maintains relative structural simplicity while creating gap regions that enable light transmission, thus resolving the contradiction between structural simplicity and optical performance.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS11257868B2Display substrate, fabricating method thereof and display device

Publication Date: 2022.02.22 BOE TECHNOLOGY GROUP CO LTD

AI summary

A display substrate includes: a base substrate including a photosensitive region, the photosensitive region including a plurality of display regions spaced apart and a gap region between the plurality of display regions; a first electrode layer on the base substrate; a light-emitting layer on a side of the first electrode layer away from the base substrate; and a second electrode layer on a side of the light-emitting layer away from the base substrate. Each display region corresponds to at least one first luminescent material region of the light-emitting layer; the gap region corresponds to the plurality of second luminescent material regions of the light-emitting layer; a part of the second electrode layer in the photosensitive region includes a plurality of second electrodes spaced apart, and an orthographic projection of each second electrode on the base substrate overlaps with each display region.