TOKYO -- In a perfect world, today's lighting based on light-emitting diodes would smoothly segue into OLED lighting made using organic electroluminescent materials.
Not only is OLED lighting energy efficient like its older sibling, but it is also thin, light and bendable. It emits light from its entire surface and in a spectrum more closely resembling natural light.
But despite all these advantages and the forecasts that OLEDs will become the next big thing in lighting, the technology has failed to find many applications yet.
The biggest problem is cost: A 10cm-square OLED panel costs hundreds of dollars, which is nearly 100 times the cost of an LED lamp of comparable brightness.
This could soon change as companies begin mass-producing OLED panels for lighting. As prices drop thanks to economies of scale, the thinness, lightness and bendability of OLED panels will make the lighting more applicable for a wider range of products, including many niches where LEDs are simply not practical.
LED lamps are made from sets of LEDs. The pointlike sources of light need plates to reflect and scatter the light across the entire lamp surface. Heat sinks are also required to shunt away the heat generated by the LEDs.
OLED lamps are different. They are made by sandwiching layers of organic materials between electrodes and placing them on a transparent substrate. When a voltage is applied to the electrodes, the entire surface of the structure emits light. There is no need for a reflective plate, and because the OLEDs do not get very hot, there is no need for heat sinks either. This makes OLED lamps thin and lightweight.
Konica Minolta is investing 10 billion yen ($97.9 million) to build a mass-production facility for OLED panels in Yamanashi Prefecture to the west of Tokyo. Come autumn, the company will have the capacity to make the equivalent of 1 million 7cm-square OLED panels.
What sets these panels apart is their bendability. OLED panels usually are fabricated on glass substrates to protect the organic materials from being damaged by moisture in the air. But Konica Minolta has leveraged its experience with photo films to develop a plastic material that serves as a barrier and can substitute for the glass. Not only is this bendable, but it reduces the thickness and the weight of the panel by four-fifths.
"Our goal is to sell these panels at a price point below 10,000 yen," marketing group leader Masahiro Nakakita said. "It's a promising material for lighting on curved surfaces inside airplanes and cars, where weight affects fuel consumption."
The company's goal for 2020 is OLED sales of 50 billion yen.
Pioneer and Mitsubishi Chemical began mass-producing OLED lighting panels together in March. The two intend to pump out the equivalent of tens of thousands of 10-by-10cm panels a month, starting this autumn.
Their production method is five to 10 times cheaper than normal.
In the conventional production process, the organic materials are vaporized and deposited on the substrate. This has the advantage of creating uniform layers, but the process is costly because the vaporized organic materials scatter in all directions, which wastes materials.
Mixing and matching
Pioneer and Mitsubishi Chemical have created a wet coating process for the mass production of OLED panels. Although uniform layers are normally hard to achieve by coating the light-emitting layer and then drying it on the substrate, the companies managed to modify the molecular composition of their organic material, said Shin Kawana of Mitsubishi Chemical's OLED business development department.
This wet coating process is also less expensive, and various parties have been expressing interest, said Kazunaga Ida of Pioneer's OLED lighting business promotion office.
Resin maker Kaneka, meanwhile, is also mass-producing OLED panels, and last year improved its manufacturing equipment. Although the company has not publicized its capacity, it is pricing its 8cm-square OLED panels at less than 10,000 yen. The company hopes that such panels could be used in art museums, since OLED lighting is closer to natural light than LED lamps and poses less threat of damage.
NEC Lighting is busy developing its own bendable OLED lighting panels. It is testing out a variety of substrates, including thin sheets of glass, plastic films and metal foils. It is also working to improve product reliability while surveying the market to determine customer needs.
As OLED lighting edges closer to the mainstream, there is increasing talk of the need for standardization. Currently, each company decides its own size and shape for its panels, the placement of electrodes and measurements of performance.
But the Japan Lighting Manufacturers Association is trying to get these companies to standardize performance metrics, said Yasuki Kawashima, manager of the solid-state lighting application engineering and development department at NEC Lighting.