Mitsubishi Electric exhibited some massive OLED displays, including a gaudy circular display, at the Consumer Electronics Show (CES) in the U.S. and Integrated Systems Europe (ISE) in 2011. Based on the company’s modular “Diamond Vision” technology, the devices combine a series of 384 mm × 384 mm panels (with 128 × 128 pixels on each) to create large-format but low-resolution displays. Elsewhere at CES, LG Display presented a [31″ OLED TV with HD resolution that it expects to offer commercially later this year. While OLEDs have stormed the market for mobile devices (especially those made by Samsung), they’ve yet to break through for larger format displays – why?
For one, OLEDs’ perpetual bug-bear – durability – is a concern for products that need to outlast the brief two- to three-year lifetime of a mobile device. More specifically, there is a big problem with differential aging of the materials; since the blue emitters degrade in performance faster than the red or green ones, the color quality of the display can drop off over time (though algorithms can compensate for these shifts to some degrees).
There are also production challenges hampering large OLEDs, as well. The shadow masks used to pattern the organic light-emitting molecules over larger displays tend to bend and bow, which makes it difficult to pattern them precisely. What’s more, active matrix (AMOLED) displays require a backplane – the thin-film transistor (TFT) array that controls the display – to be made from low-temperature polysilicon (LTPS). As opposed to the amorphous silicon (a-Si) used for most displays, LTPS is difficult and costly to make over larger areas because it requires a laser annealing step.
Demonstration devices like those from LG Display show that such challenges can be overcome – but often at a cost, driven by tougher manufacturing processes and lower yields. As a result, it’s likely that the first affordable large OLEDs will be lower-resolution devices like Mitsubishi Electric’s – though even there, LCDs will remain a formidable incumbent for the foreseeable future.