OLED? Organic Light Emitting Diode.
Organic? Organic in the sense that they utilize a carbon-hydrogen based structure (like us) versus silicon based structure for the LED’s we’ve been familiar with over the last several decades. This organic film can be deposited in thin layers on many types of materials in a process that is more like printing on paper as opposed to the complicated process for manufacturing standard LED’s and integrated circuits. This feature has great appeal for many applications, not the least of which is a flexible display screen (Take a look at a Sony OLED display.). Another advantage to the OLED technology is that it emits light, as opposed to LCD displays, which require a light source to be visible, be it ambient light from the sun or a backlight using LED’s or cold cathode fluorescent lamps (CCFL’s). Displays using OLED’s are typically brighter and richer in color, albeit they tend to be smaller in size today because of manufacturing issues.
OLED’s versus LED’s and Other Light Sources
The fact that the OLED’s, like any LED, emit light and they can be formulated to generate white light, opens up a broad application of ambient lighting for home and business. LED’s are aggressively being developed to replace the older incandescent bulbs and the newer compact fluorescent (CF) bulbs, that are being strongly marketed as green replacements. The LED’s offer even better efficiency (10% of the incandescent energy usage) over the CF bulbs (25% of the incandescent energy usage) and tremendously longer life times. They don’t come without their drawbacks and designing an LED bulb that will have a long operating lifetime and be energy efficient requires complex trade-offs in thermal, electrical and mechanical design. They are competitive with incandescents but because of their geometry they don’t lend themselves well to illuminating a large area. This is where OLED’s will outshine LED’s. Because they can be formed on surfaces of any shape, they can easily allow manufacture of cylindrical or spherical surfaces providing illumination patterns similar to incandescent and fluorescent bulbs. Even easier, and maybe more useful, they can be used to create light panels that will revolutionize the way architects and interior designers design lighting systems for homes and businesses.
OLED’s already generate more light per watt (typically 70 lumens/watt) versus 15 lumens/watt for incandescent bulbs, but they lose up to 60 percent of this light internally—it never leaves the device. New research by Stephan Forrest of Michigan University has produced a process that will allow the OLED’s to outshine fluorescents, which produce about 90 lumens/watt. His process involves integrating a grid structure of silicon dioxide that refracts this wasted light out through a layer of microlenses, which have been deposited on top the OLED. Although this complicates the manufacturing process, it still allows for cheaper manufacturing of light panels on flexible surfaces, which could transform the lighting industry.
OLED Drawbacks and the Future
OLED’s do have their problems. They are still plagued with a shorter lifetime than regular LED’s and even the CF bulbs. Work is being done to remedy this and great strides have already been made since these devices were conceived in the 1980’s. Another drawback is that OLED’s are very susceptible to moisture; therefore, any design has to ensure that they are properly sealed from moisture intrusion over the life of the product.
When you consider the efficiency and likely ease of manufacture, it is very evident that OLED technology has enormous potential—especially when you consider the myriad of ways that these devices can be integrated into your life. Take a few minutes to watch this video of GE’s idea of what’s to come.