Transparent KNN Piezoelectric Stack for Optical Transmittance

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Solution Overview

Problem

Existing piezoelectric materials lack versatility due to insufficient light transmittance, limiting their applications in devices requiring optical transparency.

Innovation Solution

A piezoelectric stack comprising a substrate, a bottom electrode film, a potassium sodium niobate (KNN) piezoelectric film with a perovskite structure, and a top electrode film, all designed for high light transmittance in the visible and near-infrared range, enhancing the piezoelectric film's optical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If conventional piezoelectric materials are used, then piezoelectric function is achieved, but light transmittance is insufficient

Engineering Contradiction:

Improvelight transmittanceVSAvoidversatility

Core Design Contradiction:

Illumination intensityVSAdaptability or versatility

Solution Approach 1:

The patent changes the compositional parameters of the piezoelectric material by using (K1-xNax)NbO3 with specific x values (0.3≤x≤0.7) and controlling the ratio of specific crystal orientations ((001) orientation ratio ≥70%). This parameter optimization achieves both high light transmittance (65% or more) and sufficient piezoelectric function, resolving the contradiction between transparency and functionality.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite piezoelectric film that combines potassium sodium niobate with specific crystal structure characteristics. By controlling the crystal orientation distribution and composition ratio, it forms a material that simultaneously provides optical transparency and piezoelectric activity, enabling versatility in transparent electronic components.

Inventive Principle:

Principle #40Composite materials

2Illumination intensity

If light transmittance is enhanced, then optical transparency is improved, but piezoelectric performance may be compromised

Engineering Contradiction:

Improvelight transmittanceVSAvoidpiezoelectric performance

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The patent optimizes multiple parameters simultaneously: composition ratio (x value between 0.3 and 0.7), crystal orientation distribution ((001) orientation ≥70%), and film thickness. This multi-parameter optimization ensures that light transmittance reaches 65% or more while maintaining adequate piezoelectric coefficients, thus improving optical transparency without compromising piezoelectric performance.

Inventive Principle:

Principle #35Parameter changes

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 piezoelectric stack achieves an average light transmittance of 65% or more, enabling applications in transparent electronic components such as touch panels and mobile phone displays, while maintaining suitable dielectric properties and etching resistance.

Implementation Method 1

A piezoelectric material is utilized widely for a functional electronic component such as a sensor and an actuator

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS12408556B2Piezoelectric stack, piezoelectric element, and method of manufacturing piezoelectric stack

Publication Date: 2025.09.02 SUMITOMO CHEM CO LTD

AI summary

A piezoelectric stack, including: a substrate; an electrode film; and a piezoelectric film comprising an alkali niobium oxide of a perovskite structure represented by a composition formula of (K1-xNax)NbO3 (0<x<1), wherein an average light transmittance through the piezoelectric film in a wavelength region of visible light and near-infrared ray is 65% or more.