A PDLC film consists of a transparent polymer layer in which microscopic droplets of liquid crystals are embedded. If no voltage is applied, the crystals in each droplet are randomly aligned — the incident light is scattered in all directions and the pane appears milky-white. As soon as 48–65 V AC voltage is applied, the crystals align themselves parallel to the electric field — the light passes through unrefracted, and the pane becomes clear.
The advantage of PDLC compared to electrochromic glass is the switching speed (approx. 200–500 ms instead of 5–15 minutes) and the availability in standard commercial glass sizes up to approx. 1.8 × 3.5 m. The disadvantage is the continuous power requirement in the transparent state (approx. 3–7 W/m²) and the clarity decreasing over time if the film is constantly under tension.
A transformer (110/230 V → 48–65 V AC, 100–600 W depending on surface area) and a switching module are required for control. The latter can be integrated into light switches, KNX, DALI, Z-Wave or into smart building systems via Cloud API.
PDLC films exist in two designs: as laminated safety glass ex-factory (durable, clean appearance, requires new manufacture) and as retrofit film for subsequent application to existing glass (faster, cheaper, visually visible film edge).