Aeroplane windows modify their transparency at passengers' request

The overall objective of IN-LIGHT (Innovative bifunctional aircraft window for lighting control to enhance passenger comfort) was to develop a new concept that combines electrochromism with transparent organic light-emitting diode (TOLED) lighting technology.

Electrochromic technology allows control over light entering the aircraft cabin to avoid a rise in the temperature while reducing air conditioning use. On the other hand, the TOLED lighting system, also controllable by passengers, provides ambient lighting with new aesthetic effects.

IN-LIGHT partners focused on the use of technologies that led to all-solid-state devices, simplifying the manufacturing process. The proposed electrochromic technology relies on light absorption by redox-chromophores placed on nanostructured semiconducting coatings supported by a conducting plastic substrate.

Typically, nanostructured electrodes with anchored chromophores are produced using a high-temperature sintering process that is not compatible with substrates such as acrylic polymers, preferred for aircraft windows. The IN-LIGHT window relies on transparent nanostructured electrodes processed at low temperatures.

Small-scale electrochromic and TOLED prototypes were produced and tested before project partners scaled up production. By the end of IN-LIGHT, electrochromic devices and TOLED stacks up to 15 cm x 30 cm were fabricated on a pilot production line using roll-to-roll assembly.

IN-LIGHT technology will make an important contribution to the competitive position of the EU aircraft industry. The combination of two technologies promises less expensive and higher-performing smart shading and dimmable aircraft windows as well as enhanced passenger comfort.