VTT develops printable light emitting film

VTT Technical Research Centre of Finland has developed a large-surface light-emitting plastic film based on OLED technology that can be created through printing.

OLED technology (Organic Light-Emitting Diode) is commonly used in mobile phone displays and television sets, though it’s normally used in glass surfaces, created using traditional microelectronics manufacturing methods.

However, VTT has found a way to print the OLED elements onto glass or steel surfaces as well as flexible plastic films, enabling significantly larger light surfaces and expanding the possibilities of the technology.

This includes the creation of patterned and flexible light-emitting surfaces on advertising displays, info signs and lighting fixtures, for example. The method also enables transparent smart surfaces to be attached to window panels or packaging.

VTT uses traditional printing methods such as gravure and screen printing, allowing for large production volumes of OLED light surfaces that can be created in traditional printing houses.

Manufactured using the gravure and screen printing methods, OLED light surfaces are around 0.2 mm thick, and include electrodes and polymer layers measuring up to a few hundred nanometres, in which the light emission occurs. This phenomenon is called electroluminescence; it entails an organic semiconductor emitting light in an electric field. The luminosity of OLED (lm/W) amounts up to around one third of an LED’s luminosity. It has one advantage: OLED emits light throughout its entire surface, whereas LED is a spotlight technology.

For now, VTT’s plastic OLED film will only emit light for around a year, since light-emitting polymer materials are susceptible to oxygen and moisture. But VTT says that it can increase the film’s lifespan as the development of screen protectors continues and the film’s application possibilities grow.

Raimo Korhonen, VTT’s Head of Research Area, explains: “The plastic film is optimally suited to advertising campaigns, in which large light-emitting surfaces can be used to draw significantly more attention than can be gained through mere printed graphics or e-ink-type black-and-white displays that do not emit light.”

It is also possible to use OLED light as a transmitter in wireless data transfer, which opens up new possibilities for utilising printed light surfaces in Internet of Things applications.

Further details from www.vtt.fi

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