ITO Nano-Whisker Alignment for Liquid Crystal Optoelectronics

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Solution Overview

Problem

Conventional liquid crystal alignment methods, such as contact-type alignment, suffer from issues like dust pollution, static electricity damage, and internal stress, while non-contact methods require conductive and transparent materials for high transmittance in optoelectronic devices, particularly in the terahertz band.

Innovation Solution

The use of indium-tin-oxide (ITO) nano-whisker layers formed through glancing angle deposition serves as both alignment layers and electrodes, aligning liquid crystal molecules and providing high transmittance with low driving voltage, avoiding the shortcomings of contact-type alignment methods.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If contact-type alignment method (polyimide rubbing) is used, then liquid crystal molecules can be aligned, but dust pollution, static electricity damage, and internal stress occur

Engineering Contradiction:

Improveliquid crystal alignment qualityVSAvoiddust pollution, static electricity damage, internal stress

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical rubbing method with a non-contact alignment approach using ITO nano-whisker layers. The nano-whiskers are formed through vapor deposition and self-align during the deposition process, eliminating the need for mechanical contact and thus avoiding dust pollution, static electricity damage, and internal stress associated with traditional rubbing methods.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the alignment mechanism from mechanical rubbing to a field-based alignment using the unique properties of ITO nano-whiskers. The nano-whiskers are deposited at specific angles (45-85 degrees) to create directional alignment without physical contact, fundamentally changing how liquid crystal molecules are oriented.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If non-contact alignment method is used, then dust pollution and static electricity damage are avoided, but conductive and transparent materials with high transmittance are required

Engineering Contradiction:

Improvedust pollution, static electricity damageVSAvoidmaterial requirements for transparency and conductivity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The ITO nano-whisker layer serves multiple functions simultaneously: it acts as the alignment layer for liquid crystal molecules, functions as a transparent electrode for applying electric fields, and provides the necessary conductivity without compromising optical transmittance. This multi-functionality eliminates the need for separate alignment layers and transparent electrodes.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent uses ITO (indium tin oxide), which is a composite material combining indium oxide and tin oxide. This composite material inherently provides both electrical conductivity and optical transparency, meeting the dual requirements for non-contact alignment and high transmittance in a single material system.

Inventive Principle:

Principle #40Composite materials

3Illumination intensity

If conventional transparent electrodes are used, then high transmittance is achieved, but high driving voltage is required

Engineering Contradiction:

Improvelight transmittanceVSAvoiddriving voltage

Core Design Contradiction:

Illumination intensityVSPower

Solution Approach 1:

The patent employs an ultra-thin ITO nano-whisker layer with thickness of 50-200 nanometers. This thin film structure minimizes electrical resistance while maintaining high optical transmittance, enabling both high light transmission and low driving voltage requirements for the liquid crystal device.

Inventive Principle:

Principle #30Flexible shells and thin films

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 ITO nano-whisker structured electrodes and alignment layers offer high transmittance and low driving voltage, suitable for terahertz band optoelectronic devices, and can be applied to subtle high-precision elements, enhancing the performance and precision of liquid crystal based optoelectronic devices.

Implementation Method 1

the ITO nano-whisker layer is formed by glancing angle deposition, wherein an angle between a vapor flux direction and the normal direction of the substrate where the vapor is deposited is 40° ̃80°

Methodology Applied

Scientific EffectGlancing angle deposition: Physical Vapour Deposition

Implementation Method 2

The ITO nano-whisker layer is used as a transparent electrode for driving the tilt direction of the liquid crystal molecules

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

a liquid crystal layer sandwiched between the upper substrate and the lower substrate

Methodology Applied

Scientific EffectLiquid crystal electro-optic effect: Electro-Optic Effects

Data Source

PatentUS9810947B2Liquid crystal based optoelectronic device

Publication Date: 2017.11.07 NATIONAL TSING HUA UNIVERSITY

AI summary

The invention provides a liquid crystal based optoelectronic device, including an upper substrate and a lower substrate, a liquid crystal layer sandwiched between the upper substrate and the lower substrate, and a pair of indium tin oxide nano-whisker layers formed on the inner surfaces of the upper substrate and the lower substrate, wherein the indium tin oxide nano-whisker layer is used as an alignment layer for aligning liquid crystal molecules in the liquid crystal layer.