Recessed Light Blocking Portion for OLED Transistor Stability

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Solution Overview

Problem

In OLED display panels, particularly for bottom emission type displays, light emitted from organic light-emitting diodes easily incidents upon driving transistors, leading to stability issues and degradation of display quality due to illumination leakage current.

Innovation Solution

An array substrate design featuring a recessed portion with a light blocking portion on the planarization layer surrounding the active layer of the transistor, preventing light from reaching the active layer, which is formed using a dry etch process and filled with a light-blocking material, such as a black light-absorbing material, to enhance stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If light blocking structures are added to prevent light from incidenting on the active layer, then the stability of the driving transistor is improved, but the device complexity increases

Engineering Contradiction:

Improvestability of driving transistorVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The light blocking portion is nested within the recessed portion of the planarization layer, creating a hierarchical structure where one element is placed inside another. This nested configuration effectively blocks light from reaching the active layer while maintaining a compact design that does not significantly increase overall device complexity.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The solution transitions from a two-dimensional planar structure to a three-dimensional structure by creating a recessed portion that extends vertically into the planarization layer. This dimensional change allows light blocking without requiring additional lateral space, thus improving transistor stability without proportionally increasing device complexity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Object-affected harmful factors

If a recessed portion is formed in the planarization layer to accommodate light blocking material, then light leakage is prevented, but the manufacturing process becomes more complex

Engineering Contradiction:

Improvelight leakageVSAvoidfabrication process

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The recessed portion is formed in the planarization layer before the light blocking material is deposited. This preliminary action creates a pre-prepared structure that guides subsequent manufacturing steps, allowing the light blocking material to be easily filled into the recessed area using standard deposition and patterning processes.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The manufacturing process is segmented into distinct steps: forming the recessed portion, depositing the light blocking material, and patterning. This segmentation allows each step to be optimized independently using existing manufacturing techniques, reducing overall process complexity despite the added structural feature.

Inventive Principle:

Principle #1Segmentation

3Reliability

If the light blocking portion is entirely within the recessed portion, then light blocking effectiveness is maximized, but the area of the active layer is reduced

Engineering Contradiction:

Improvelight blocking effectivenessVSAvoidactive layer area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The light blocking structure is localized specifically to the recessed portion areas surrounding the active layer, rather than uniformly covering the entire device. This local quality approach ensures effective light blocking where needed while preserving maximum active layer area for device operation.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The recessed portion is positioned asymmetrically around the active layer, with the light blocking material concentrated in specific regions where light leakage is most problematic. This asymmetric configuration optimizes light blocking effectiveness while minimizing encroachment on the active layer area.

Inventive Principle:

Principle #4Asymmetry

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 effectively blocks light from incident upon the active layer of the driving transistor, reducing instability and maintaining display quality by preventing light leakage, thus improving the stability and performance of OLED display panels.

Implementation Method 1

the light blocking portion is configured to prevent a light from being incident upon an active layer

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 2

forming a recessed portion on the planarization layer; the forming a recessed portion comprises: forming the recessed portion on at least one side of the planarization layer facing to the active layer of the transistor through a dry etch process

Methodology Applied

Scientific EffectDry etching:

Data Source

PatentUS10978539B2Array substrate having a recessed and light blocking portion and fabrication method thereof, and display device

Publication Date: 2021.04.13 HEFEI XINSHENG OPTOELECTRONICS TECH CO LTD

AI summary

An array substrate includes a base substrate, a transistor on the base substrate, a planarization layer on a side of the transistor away from the base substrate, a recessed portion on the planarization layer, and a light blocking portion in the recessed portion. The light blocking portion is configured to prevent a light from being incident upon an active layer.