Functional element having electrically controllable optical properties

A composite pane having a functional element having electrically controllable optical properties, comprising:

• a stack sequence of an outer pane, a first intermediate layer, a second intermediate layer, and an inner pane, wherein the intermediate layers contain at least one thermoplastic polymer film having at least one plasticizer, and
• a functional element having electrically controllable optical properties is arranged, at least in sections, between the first intermediate layer and the second intermediate layer, and
• the functional element is a polymer dispersed liquid crystal (PDLC) functional element,
• wherein the functional element comprises a second stack sequence of at least
• a first carrier film,
• an active layer, and
• a second carrier film, and
• wherein at least one exit surface of the active layer is sealed, at least in sections, on at least one lateral surface of the functional element by at least one barrier layer,
• the barrier layer is implemented such that the barrier layer substantially prevents the diffusion of plasticizer through the barrier layer, and
• the barrier layer is produced by a vacuum-based thin-film deposition method.