B. Barrier Layers
Barrier layers are a bugger. Ten years ago I asked the CEO of Cambridge Display Technologies when we were going to get a roll-up display and he said I could have one now if they could only find a barrier layer to protect the display from the water in the atmosphere.
Good I thought, roll-ups won’t be long now. How wrong I was. The organic displays guys are still searching for a barrier layer technology.
The EU has an Imec-co-ordinated project called IMOLA (Intelligent light Management for OLED on foil Applications) to develop large-area OLED lighting modules with built-in intelligent light management.
The biggest problem, still, is finding a barrier layer.
Under perfect conditions, OLED materials are now lasting just about long enough for commercial use.
However, some of the layers needed to make efficient OLEDs structures are chemically-delicate and are rapidly corroded by the atmosphere.
Sandwiching them between two sheets of glass and hermetically sealing the edges is one way to keep them safe, but for cost reasons lighting firms want to print OLED on flexible plastic substrates using roll-to-roll machinery.
Plastic is far-too permeable to exclude damaging water and oxygen.
Getters – reactive layers that bind with moisture and oxygen before it can reach the OLED – can help, but what are really needed are coatings – barrier layers – that can be applied cheaply to block atmospheric ingress.
Intense efforts world-wide to develop such barrier layers have so far met with limited success.
Yes, it’s a bugger.