Different transparent materials have different haze, which leads to visual differences. We analyze the reasons that lead to haze differences in transparent materials, compare the haze performance of different dimming technologies, and unlock the secret of why electro-variable dimming technology can maintain the best clarity.
The term “haze” refers to the level of light diffusion in materials like smart films or glass, particularly in dimming technologies. It measures how much light is scattered when passing through a material. Higher haze values generally indicate more light scattering, resulting in a frosted or opaque look, while lower haze values mean clearer or more transparent material.
Different dimming technologies exhibit varying levels of haze depending on their mechanisms and capabilities. Below is an overview of how haze behaves in different dimming technologies:
PDLC Technology (Polymer Dispersed Liquid Crystal)
How It Works:
PDLC films contain liquid crystal droplets dispersed in a polymer matrix.
In the off-state, light is scattered by the misaligned liquid crystals, creating a frosted or opaque appearance (high haze).
In the on-state, an electric current aligns the crystals, allowing light to pass through (low haze).
Haze Levels:
Transparent State (ON): ~2%–10% haze (depends on quality and manufacturing).
Opaque State (OFF): ~80%–95% haze (diffused light for privacy).
Applications:
Privacy windows, partitions, skylights.
Key Feature: High privacy in the opaque state.
Electrochromic Technology
How It Works:
Electrochromic materials change their tint or transparency when voltage is applied, by rearranging ions and electrons in the material.
The tinting process reduces visible light transmission but does not significantly diffuse light.
Haze Levels:
Lightly Tinted State: ~1%–5% haze.
Fully Darkened State: ~5%–10% haze (slight haze due to tinting but not frosted).
Applications:
Building facades, automotive windows, and skylights.
Key Feature: Gradual dimming with very low haze values (clear view even when darkened).
SPD Technology (Suspended Particle Device)
How It Works:
Suspended particles within the film align when an electric current is applied, allowing light to pass through.
In the off-state, the particles are randomly oriented, blocking and scattering light.
Haze Levels:
Transparent State (ON): ~1%–3% haze (very clear).
Darkened State (OFF): ~10%–20% haze (more of a tinted look than frosted).
Applications:
Automotive sunroofs, windows, and skylights.
Key Feature: Provides variable tinting with minimal haze, maintaining transparency.
Thermochromic Technology
How It Works:
Materials or films respond to temperature changes, transitioning between clearer and tinted states.
Light transmission is reduced in the tinted state, but haze values remain relatively low since the material does not scatter light.
Haze Levels:
Clear State (Low Temperature): ~1%–3% haze.
Tinted State (High Temperature): ~5%–10% haze.
Applications:
Passive solar control in windows, greenhouses, and skylights.
Key Feature: Automatic temperature-based dimming with low haze.
Photochromic Technology
How It Works:
Similar to thermochromic materials, but the transition is triggered by UV light exposure.
As the material darkens in sunlight, it reduces visible light transmission without significant scattering.
Haze Levels:
Clear State (No UV): ~1%–3% haze.
Darkened State (High UV): ~5%–10% haze.
Applications:
Automotive windows, eyewear, and outdoor glass installations.
Key Feature: UV-triggered dimming with low haze levels.
Hybrid Smart Films
How It Works:
Combines technologies like PDLC and SPD or PDLC with solar-reflective coatings.
Haze depends on the dominant technology; PDLC layers usually introduce higher haze.
Haze Levels:
Transparent State: ~2%–10% haze (depending on technology mix).
Opaque State: ~60%–95% haze (if PDLC is integrated).
Applications:
High-end residential or commercial projects requiring multifunctional dimming.
Key Feature: Versatility in controlling haze, light transmission, and solar control.
Haze Comparison of Dimming Technologies
| Technology | Transparent State Haze | Opaque/Darkened State Haze | Key Feature |
|---|---|---|---|
| PDLC | ~2%–10% | ~80%–95% | High privacy with frosted appearance. |
| Electrochromic | ~1%–5% | ~5%–10% | Gradual tinting with low haze. |
| SPD | ~1%–3% | ~10%–20% | Variable tinting with minimal haze. |
| Thermochromic | ~1%–3% | ~5%–10% | Passive dimming with low haze. |
| Photochromic | ~1%–3% | ~5%–10% | UV-triggered dimming with low haze. |
| Hybrid Films | ~2%–10% | ~60%–95% (if PDLC is used) | Multifunctional dimming capabilities. |
The haze level is an important factor when choosing dimming technologies, as it impacts the visual clarity, privacy, and aesthetic of the material:
- PDLC Films: Best for privacy applications due to high haze in the opaque state.
- Electrochromic and SPD Films: Ideal for solar control with low haze, maintaining clear views.
- Thermochromic and Photochromic Films: Provide passive dimming with minimal haze, suitable for energy efficiency.
- Hybrid Films: Offer a balance of privacy, solar control, and haze levels, depending on the combination of technologies.
