Continuing with our updates on the slow but sure progress that is being made in the field of OLED monitors, we bring you news that a major player, DuPont, has presented its latest OLED technology at an SID (Society for Information Display) 2011 conference in LA. DuPont is a pontentially very important supply partner for manufacturing equipment to the factories of companies such as Samsung, LG and Sony who have been most vocal about their commitment to OLED TVs, PC monitors and small form factor displays.

The solution-based coating techniques include the ‘slot-coating’ or Hole Injection Layer (HIL) deposition of a primer layer followed by continuous nozzle printing for the Elevated Mixed Layer (EML) which contains the red, green and blue materials. This layering process is summarised in the diagram below:

The current most widely used fabrication method for OLED displays involves depositing materials through a fine metal mask using evaporation. There is a significant amount of wastage using such a process and it can’t currently be applied to large glass substrates – leading to a high cost to the consumer when considering a large-screen end product such as a computer monitor or TV screen. Solution coating technologies such as those under development by DuPont scale much better to large screen sizes and offer massive cost-saving potential. DuPont estimate that a small sized OLED display, such as that used in a tablet PC, could cost around 20% less than a ‘comparable’ LCD display with significantly higher cost improvements for larger sized displays such as PC monitors and televisions.

With recent advances in the coating process the company has managed to overcome problems which traditionally hampered efforts to commercialise such a technique. These include vast improvements to the physical and thus visible uniformity on many levels over previous solution-based deposition techniques; intra-pixel, inter-pixel and ‘long range’ (i.e. across the entire display) colour vatiation or mura. The new technique is reported to offer additional improvements to end-product performance over both thermal evaporation and traditional solution coating methods with greater useful lifetimes. The expected lifetime of blue subpixels was calculated as 40,000 hours (4.56 years), red subpixels as 29,000 hours (3.31 years) and green subpixels as 230,000 hours (26.24 years). Interestingly the overall lifetime of the blue subpixel components is now expected to exceed the red subpixel components, with substantial gains in the already ‘strong’ green subpixel lifetime.

It should be noted that this doesn’t take into account degredation over the life of the product and considers only the absolute end point. Nonetheless these figures conservatively assume continuous 100% illumination of all subpixels (i.e. a full white image). In reality a user doesn’t leave their monitor on in an active state 24 hours a day and doesn’t stare at an entirely white image continuously, either. DuPont seem rather confident that their current techniques and materials can help to make OLED screens of all sizes a commercial success and are making excellent progress towards making many people’s ‘dream display’ a reality. You can read more about the solution coating technology here.