Liquid Crystal Composition Stabilizer for Afterimage Reliability

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Solution Overview

Problem

Liquid crystal compositions with alkenyl groups exhibit high-speed response characteristics but suffer from reliability issues such as linear afterimages due to alkenyl by-products generated by heat and UV exposure, and previous stabilizers have insufficiently addressed these problems.

Innovation Solution

Incorporating a stabilizer with an N-oxyl radical structure, represented by Formula 1-1, into the liquid crystal composition to enhance afterimage reliability, potentially combined with additional stabilizers and antioxidants to improve voltage holding ratio and resistance to thermal and electrical stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If liquid crystal compounds with alkenyl groups are used to achieve high-speed response characteristics, then response speed is improved, but reliability deteriorates due to linear afterimages caused by alkenyl by-products generated under heat and UV exposure

Engineering Contradiction:
Improveresponse speedVSAvoidafterimage reliability
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

A stabilizer compound with specific molecular structure (Formula 1-1) is introduced as an intermediary substance to intercept and neutralize the harmful alkenyl by-products generated during heat and UV exposure. This stabilizer acts as a mediator between the liquid crystal compounds and the environmental stressors, preventing the formation of linear afterimages while allowing the liquid crystal to maintain its high-speed response characteristics

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention converts the harmful effect of alkenyl by-product generation into a beneficial outcome by using the stabilizer to capture these by-products. The stabilizer undergoes controlled reactions with the alkenyl groups, transforming what would be damaging degradation products into stable, non-harmful compounds that do not cause afterimages, thus turning the reliability problem into a controlled chemical process

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

2Speed

If liquid crystal compounds with alkenyl groups are used to achieve high-speed response characteristics, then response speed is improved, but voltage holding ratio deteriorates under thermal and electrical stress

Engineering Contradiction:
Improveresponse speedVSAvoidvoltage holding ratio
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The stabilizer compound is incorporated into the liquid crystal composition in advance to provide protective cushioning against thermal and electrical stress. Before damage can occur to the liquid crystal molecules, the stabilizer is already present to prevent degradation reactions, thereby maintaining voltage holding ratio under stress conditions while preserving the high-speed response characteristics of the alkenyl-containing liquid crystal compounds

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Speed

If liquid crystal compounds with alkenyl groups are used to achieve high-speed response characteristics, then response speed is improved, but resistance to thermal stress deteriorates

Engineering Contradiction:
Improveresponse speedVSAvoidthermal stress resistance
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The stabilizer serves as a thermal intermediary that absorbs and dissipates thermal energy before it can cause degradation of the liquid crystal molecules. The stabilizer compound has thermal stability properties that allow it to protect the alkenyl-containing liquid crystal compounds from thermal degradation, maintaining both response speed and thermal stress resistance

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP3053990B1Liquid crystal composition and liquid crystal display including the same
Publication Date: 2019.04.10 SAMSUNG DISPLAY CO LTD
  • EP3053990B1 patent drawingFigure 1
  • EP3053990B1 patent drawingFigure 2
  • EP3053990B1 patent drawingFigure 3

AI summary

Disclosed is a liquid crystal composition. The liquid crystal composition includes liquid crystal molecules including at least one of a liquid crystal compound having an alkenyl group and a liquid crystal compound having an alkoxy group, and a first stabilizer including a compound having a structure represented by Formula 1: where n is 0 or 1; m is 0 or 1; k is 0 or 1; Z1, Z2, and Z3 are each independently a single bond, -C=C-, -OCO-, -COO-, -CF2O-, or a C1 to C5 alkylene group; X1, X2, X3, and X4 are each independently hydrogen or halogen; Y is hydrogen, a C1 to C10 alkoxy group, a hydroxyl group, -NHCOCH3, or =O; and A and B are cyclic compounds.