The International Consumer Electronics Show has always been an interesting birthing ground for new display technologies and this year seems no different.
One product getting lots of attention is the new super skinny 55-inch television from LG that uses OLEDs to create a great picture with deep black level, and saturated color.
Knowing my long history in the display industry, several people have asked me to explain to them what OLEDs are so it seemed like a good opportunity to do a post here in case others out there are looking for some background about the science of it.
The LG television set, and others like it represent a somewhat traditional evolution of a great discovery. Organic Light Emitting Diodes (OLEDs) were initially discovered by Roger Partridge at the National Physical Laboratory in the United Kingdom around 1975. Subsequently, in 1979, Chin Tang and Steven Van Slyke discovered a similar effect while exploring chemical conductance of solar cells at Kodak.
Fundamentally, OLED elements are two conductive electrodes (the cathode and diode) that are separated by a small gap that is filled with carbon-based molecules (hence the O for organic in OLED). These molecules are sandwiched between the two electrodes. When a current is generated across the electrode plates, electrons pass through the trapped organic semiconductors and light is emitted.
Pretty straightforward principles but it has several advantages over other display illumination approaches (i.e. the backlight required for LCD) including energy efficiency, color reproduction capability
and cost of manufacturing. In fact, most of the past 30 years since the discovery of OLEDs was spent developing more efficient manufacturing processes – yet the basic design principles haven’t changed.
Today, I can walk the CES show floor and find many products that embed OLED. This discovery, now known as electroluminescence, is the basis for the OLEDs we carry in our cell phones and utilize in thin televisions. Hooray for the incorporation of basic science into practical applications!
Of course there are other ways to create illumination for a display. I’ve posted in the past about some of these technologies and I’m hoping to get a good look at some of the new laser-based illumination platforms out there so that will be the topic of a future post.