Oct. 04, 2026
Smart glass and smart film are general terms for glazing technologies that can change their optical properties to provide privacy, light control, solar shading or energy management.
However, not all smart glass works in the same way. Different technologies use liquid crystals, suspended particles, electrochromic materials or light-responsive materials to control how glass interacts with light.
The main technologies currently include PDLC, PNLC, DLC, EP (SPD), EC and Photochromic Glass. Each technology has different characteristics and is suitable for different applications.
PDLC (Polymer Dispersed Liquid Crystal) is one of the most widely used smart privacy technologies.
PDLC contains liquid crystal droplets dispersed within a polymer matrix. When electricity is applied, the liquid crystals change their orientation and control how light passes through the film.
Power OFF → Frosted / Privacy
Power ON → Transparent
Its main advantage is instant privacy control while still allowing natural light into the space.
PDLC is widely used for office partitions, meeting rooms, hotel bathrooms, healthcare facilities, residential spaces and glass doors.
It is available as self-adhesive smart film, non-adhesive film, laminated smart glass and smart glass IGU.
PNLC (Polymer Network Liquid Crystal) is also based on liquid crystal technology but can operate in reverse mode compared with conventional PDLC.
A typical reverse-mode PNLC product works as:
Power OFF → Transparent
Power ON → Frosted / Privacy
The ability to remain transparent without continuous power makes PNLC particularly attractive for applications where clear glass is required most of the time.
PNLC can be used for offices, meeting rooms, doors, windows, partitions and other privacy glazing applications.
DLC (Dye Liquid Crystal) combines liquid crystal and dye materials.
Instead of simply changing between transparent and frosted states, DLC can provide a transition between a transparent state and a dark privacy state.
This gives DLC two important functions:
Privacy + Light/Solar Control
The darker state helps reduce excessive visible light while providing privacy, making DLC particularly suitable for windows, doors, hotel rooms, curtain walls and skylights.
For applications where conventional PDLC privacy is not enough and additional sunlight control is required, DLC provides another option.
EP technology is based on a principle similar to SPD (Suspended Particle Device) technology.
Instead of liquid crystals, electrically responsive suspended particles control how much light passes through the film.
By adjusting the applied voltage, the film can continuously change from a dark tinted state to a highly transparent state.
The main characteristics of EP (SPD) include:
Fast response
Continuous dimming
Adjustable visible light transmission
Solar and glare control
Clear outside views
These characteristics make EP (SPD) particularly suitable for automotive windows and sunroofs, architectural windows, curtain walls, skylights and glass roofs.
EC (Electrochromic) Smart Glass uses electrochromic functional materials that change their optical properties through an electrochemical process.
When a small electrical voltage is applied, ions move within the functional layers and gradually change the tint of the glass.
Unlike PDLC, EC technology is mainly designed for solar and daylight control rather than instant privacy.
Traditional EC products are generally coating-based glass products rather than conventional smart films and are commonly incorporated into an IGU structure.
EC can be used for architectural windows, façades and curtain walls where gradual dynamic solar control is required.
Flexible EC smart film is also being developed by some companies, although it remains an emerging technology compared with more established smart film systems.
Photochromic Glass works differently from electrically controlled smart glass because it does not require electricity.
Photochromic materials respond automatically to UV intensity in sunlight.
Strong Sunlight → Darker
Weak Sunlight → Lighter
The glass therefore automatically adjusts its tint according to changing outdoor light conditions.
Because no wiring or electrical control system is required, Photochromic Glass provides a simple passive solar-control solution for windows, curtain walls, skylights and glass roofs.
The easiest way to understand the differences is by looking at their primary functions.
| Technology | Main Function | Typical Switching | Best For |
|---|---|---|---|
| PDLC | Privacy | Frosted ↔ Clear | Offices, partitions, hotels, healthcare |
| PNLC | Reverse Privacy | Clear ↔ Frosted | Spaces normally requiring clear glass |
| DLC | Privacy + Light Control | Dark ↔ Clear | Windows, hotels, curtain walls, skylights |
| EP (SPD) | Solar & Light Control | Dark Tint ↔ Clear | Windows, curtain walls, skylights, automotive |
| EC | Solar Control | Gradual Tinting | Windows, façades, curtain walls |
| Photochromic | Passive Solar Control | Light ↔ Dark by sunlight | Windows, skylights, curtain walls |
PDLC, PNLC, DLC and EP (SPD) can all be manufactured using functional film structures.
Depending on the technology and product configuration, these films can be incorporated into laminated glass to manufacture finished smart glass.
A typical structure is:
Smart Film → Laminated Smart Glass → Smart Glass IGU
PDLC and some other technologies can also be supplied as self-adhesive smart film for installation onto existing glass.
Traditional EC technology, by comparison, is generally based on functional coatings applied to glass rather than the same film structure.
Photochromic materials can also be incorporated into laminated glass using functional interlayers.
Another useful way to classify smart glass is by its main purpose.
For privacy control, PDLC and PNLC are usually the primary choices.
For privacy combined with darker light control, DLC can be considered.
For dynamic solar control with clear outside views, EP (SPD) is particularly suitable.
For gradual electrically controlled solar shading, EC provides another solution.
For automatic solar shading without electricity, Photochromic Glass can be used.
The right technology depends on what you want the glass to achieve.
If the main requirement is instant privacy, choose PDLC.
If the glass should normally remain clear without power, consider PNLC.
If both privacy and sunlight control are required, DLC may be more suitable.
If the project requires fast and continuously adjustable solar control, particularly for windows, skylights or automotive glazing, EP (SPD) is a strong option.
If gradual solar control is acceptable, EC can be considered.
If automatic shading without electrical power is preferred, Photochromic Glass provides a passive alternative.
There is therefore no single “best” smart glass technology. The correct solution depends on privacy requirements, solar control, optical performance, switching speed, installation environment, glass structure and project budget.
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