Titanium Nitride IR Reflecting Coatings for Window Energy Efficiency

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Solution Overview

Problem

Conventional solar control coatings for windows struggle to achieve a combination of low solar factor (SF), low solar heat gain coefficient (SHGC), high light-to-solar gain ratio (LSG), and desirable reflective coloration without sacrificing visible transmission or increasing red reflective coloration, especially when using non-deeply tinted glass substrates.

Innovation Solution

The use of titanium nitride (TiN) as infrared (IR) reflecting layers sandwiched between dielectric layers, such as silicon nitride, in a coating structure that excludes silver-based IR reflecting layers, to achieve improved emittance, SHGC, and LSG values while maintaining thermal stability and reducing red reflective coloration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional solar control coatings use NbN, NbZr, or NbZrN as IR reflecting layers, then the coating structure can achieve low solar factor and solar heat gain coefficient, but the normal emittance values become undesirably high, SHGC values remain high, and LSG values become low

Engineering Contradiction:

Improvesolar heat gain coefficientVSAvoidnormal emittance

Core Design Contradiction:

Loss of energyVSQuantity of substance

Solution Approach 1:

The patent changes the material composition parameter of the IR reflecting layer from conventional NbN, NbZr, or NbZrN to titanium nitride (TiN). This material substitution fundamentally alters the optical properties, achieving lower normal emittance values while maintaining low SHGC and improving LSG ratios, thereby resolving the contradiction between energy loss control and emittance reduction

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite coating structure consisting of multiple layers including TiN IR reflecting layers combined with dielectric layers (such as silicon nitride) and other functional layers. This composite architecture enables optimization of both thermal control properties and optical properties, achieving low emittance and low SHGC simultaneously while improving LSG

Inventive Principle:

Principle #40Composite materials

2Loss of energy

If conventional low-E coatings are designed for monolithic window applications, then low solar heat gain coefficient can be achieved, but visible transmission becomes low and reflective coloration becomes undesirable (too red)

Engineering Contradiction:

Improvesolar heat gain coefficientVSAvoidvisible transmission

Core Design Contradiction:

Loss of energyVSIllumination intensity

Solution Approach 1:

The patent applies local quality by designing different layers with specific functions: the TiN IR reflecting layers provide thermal control, while dielectric layers (silicon nitride) and other layers are optimized for visible light transmission and color control. This localized functional differentiation allows the coating to achieve low SHGC while maintaining high visible transmission and neutral coloration

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent controls and optimizes the reflective coloration of the coating by carefully selecting layer materials and thicknesses. The TiN-based coating system produces desirable reflective colors that are not excessively red, while the dielectric layers enhance visible transmission. This color optimization resolves the contradiction between energy efficiency and aesthetic appearance

Inventive Principle:

Principle #32Color changes

3Loss of energy

If the coating includes silver-based IR reflecting layers, then low solar heat gain coefficient can be achieved, but the coating loses thermal stability upon heat treatment

Engineering Contradiction:

Improvesolar heat gain coefficientVSAvoidthermal stability

Core Design Contradiction:

Loss of energyVSStability of the object's composition

Solution Approach 1:

The patent replaces the expensive and thermally unstable silver-based IR reflecting layers with titanium nitride (TiN), which is more thermally stable and suitable for heat-treatable applications. While TiN may have different optical properties, it provides the necessary thermal stability for monolithic and IG window applications requiring heat treatment, thereby resolving the contradiction between energy efficiency and thermal stability

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 coating achieves desirable visible transmission, low SHGC, high LSG, and neutral or non-red reflective coloration, maintaining mechanical, chemical, and environmental durability, suitable for monolithic, insulating glass, and laminated windows.

Implementation Method 1

at least one functional infrared (IR) reflecting layer(s) sandwiched between at least dielectric layers... at least one of the IR reflecting layers is of or including titanium nitride (e.g., TiN)

Methodology Applied

Scientific EffectInfrared reflection: Reflection

Data Source

PatentEP4122898A1Heat treatable coated article having titanium nitride based IR reflecting layer(s)

Publication Date: 2023.01.25 GUARDIAN GLASS LLC

Figure 1

AI summary

Coated articles include at least one functional infrared (IR) reflecting layer(s) sandwiched between at least dielectric layers. The dielectric layers may be of or including silicon nitride or the like. At least one of the IR reflecting layers is of or including titanium nitride (e.g., TiN).