Three main parameters matter for display in this market: image quality (in a variety of conditions, like indoor/outdoor viewing); power consumption; and physical aspects, like size and weight. Every display technology has to provide a competing image quality to succeed, but those that are used in mobile devices have to do it with as low power consumption as possible while being very thin and lightweight. This is the same feature that let OLED displays to find a niche and to at least take the place of LCD in some products. OLEDs not only deliver some image quality advantages (especially in the areas of contrast and viewing angle), they can also be very thin, lightweight, and in most cases, will provide some power efficiency advantages over an equivalent LCD.
However, even OLED display technology isn’t perfect. These displays lose brightness over time, and disparate aging rate across the three colors make it challenging to maintain the correct color balance over time. Cost can be an issue, too; Production of OLEDs has more cost than LCDs, which has limited their use to the higher end products, until now. Of course, neither LCDs nor OLEDs are completely mature technologies – there’s still a good deal of development going on in both types.
Naturally, plenty of new technologies have been announced in the last decade and many of them with great fanfare and high expectations. Based on the first specs release, you could assume that every one of them would be the Next Big Thing in the industry of displays and take the complete domination in the market just in a few years. It had never happened though, even with the heavy investment of some big names in the industry to bring them to commercial success or at least viability.
An electrowetting display technology introduced by Dutch electronics giant Philips (one which works by controlling fluids via electric charges), is a good example here. Philips spun off a new company named LiquaVista, in 2006 to commercialize this display technology. The LiquaVista display that marketed as “LCD 2.0,” had the promise of both emissive and reflective modes, excellent viewing angles and color, and fast response times. All in a display that could be produced using more-or-less conventional processes and which would require much less power than a comparable LCD. The company and its technology were sold to Samsung in 2010, and then Samsung sold it to Amazon in 2013. After Four years, we still haven’t seen a product using an electrowetting display.
However, other new displays haven’t been so lucky. Within seven years (from 2004 to 2011), giant chip-maker Qualcomm bought two separate startups that were working on two very distinct microelectromechanical systems (MEMS)-based displays: Iridigm that has been working on reflective iMOD technology, and Pixtronix from Boston-area with a direct-view micro-shutter display. By 2015, both efforts were quietly stopped.
UniPixel Displays demonstrated another type of electromechanical-shutter display called the Time-Multiplexed Optical Shutter (TMOS) but again became another example of failing in transition to commercial production. Maybe LCDs and OLEDs are going to be it, at least for as long as we can currently predict.
With all that said, there’s still one other technology which has been seeing a lot of interest from some big players in the business. This one promises great color, contrast, viewing angle, brightness, and response time while has a lower impact on your battery than the best examples of either incumbent. It’s another type of LED: the original one. The inorganic, good-old-semiconductor form of light-emitting diodes, that’s now behind our light bulbs or blinks as little red, green, blue, and white lights on almost every piece of consumer electronics you can think of.
LEDs can meet with almost all you’d demand from a display technology. You can find them in various colors, including the three important primaries for displays: red, green and blue. LEDs use an emissive technology; it means that viewing angle wouldn't be an issue with them. Just like OLED, their contrast/dynamic range is excellent. Energy-efficiency of conventional LEDs are much more than OLEDs or backlit LCDs. Obviously, they don't need any color filters or polarizers and switch on or off just in a few microseconds.
In fact, conventional LEDs have already become the base of displays that are viewed by millions of people every day. The only thing is that they are much farther away from smartphones and other mobile products than you could imagine. We are talking about really, really big full-color displays you see today in public places like sports stadiums, in billboards and other digital signage, and recently even movie theater screens.
The problem with using conventional LEDs as the pixels or rather, subpixels (Small dots in three main colors that combination of their light will define pixel’s final color) in mobile screens, isn’t manufacturing the devices in the nearly-microscopic sizes needed. The main challenge is trying to put everything together on a single small display. Even a modest 1280 x 720 screen needs almost three million separate LEDs, which would be more than 920,000 each of red, green, and blue emitters. Putting them all on a single common substrate wouldn't be a simple task, too; LEDs with different colors are made from very different materials.