There are two types of electronic devices: those that have displays and those that soon will. As electronic control spreads to more and more products, the items need displays to tell us what they’re doing and what we’ve commanded them to do. With the market for displays at nearly US $100 billion and rising, and with technology research growing apace, there’s a need for the new Journal of Display Technology. The quarterly, to be unveiled this month, is being sponsored by seven IEEE societies and the Optical Society of America.

Colors are bright in a flexible display made of a hybrid of inorganic and organic LEDs by a group at the University of Cincinnati.

The collaboration between the societies is a natural fit, according to the journal’s editor in chief, S.T. Wu, who is a Fellow of both the IEEE and the OSA. Wu, a professor of optics at the University of Central Florida in Orlando, intends the interdisciplinary journal to fill a gap between the short reports in conference proceedings and peer-reviewed journals that cover only specific display technologies. The JDT will cover physics, applications, manufacturing, reliability, and testing. The display types discussed in the inaugural issue include transflective and other liquid-crystal displays, organic and inorganic light-emitting diodes, and a new type of atmospheric-pressure plasma.

SUPERB IMAGES  “Organic LEDs have become the darling of future flat-panel displays,” says Chin H. (“Fred”) Chen, a professor at the Display Institute of the National Chiao Tung University in Hsin-chu, Taiwan, and a contributor to the first issue. Originally restricted to small portable displays, OLEDs, because of their superb display quality, have “great potential for [computer] notebooks, monitors, and eventually for TV,” says Chen, who worked at Kodak with Ching Tang, credited as the inventor of OLEDs. For the new journal, Chen’s group of researchers at the institute wrote about the development of efficient and robust blue fluorescent OLED materials and devices, critical issues in OLED design, because blue OLEDs have historically suffered from inadequate life and relatively weak color output.

“There are two types of OLEDs,” says Yang Yang of the University of California at Los Angeles School of Engineering, “those using polymers and those based on smaller organic molecules. Small-molecule displays are typically made in a high-vacuum chamber.” But polymer LEDs can be printed, using an inkjet printer of unusually high precision.

Both display types offer a rich variety of colors, are easy and inexpensive to fabricate, and are emissive like cathode ray tubes, Yang says, noting that his group’s JDT paper covers ways of making electrodes “very transparent, so you can see an image from each side—or very opaque, so we can have a high contrast level.”

VIBRANT COLORS  Combine organic with inorganic LED technology and you get the best of both worlds, says Andrew Steckl, director of the Nanoelectronics Laboratory at the University of Cincinnati. “Inorganic LEDs,” Steckl, says, “are very bright and robust but are normally point sources—they cannot be made into large-area sources for flat-panel displays and certain types of lamps. OLEDs are also very bright and can be made into large-area sources at low cost, but they have short life times at the currents required for high brightness.”

Steckl, an IEEE Fellow, is a contributor to the JDT’s first issue. He notes that in hybrid inorganic/organic displays and solid-state lamps [see photo], “we use an inorganic violet or ultraviolet light source as a pump for organic materials, which absorb the pump light and emit at various visible colors.”

The organic lumophores—materials that emit light at specific colors—are optically pumped and do not have electric current flowing in them, lengthening their life, Steckl says. He expects to produce displays with superior performance at lower cost than either liquid-crystal or plasma displays.

Other researchers are pushing ahead with plasma devices. “Plasmas, such as those produced in arc lamps or thermonuclear fusion experiments, have a reputation as being violent or ill-behaved,” notes Gary J. Eden, director of the Laboratory for Optical Physics and Engineering at the University of Illinois in Urbana. “But when we shrink them way down to roughly 150 micrometers or less, the result is stable, uniform plasmas compatible with electronic or optical systems.”

The smaller the plasma cell, the higher its operating pressure. Make them small enough, and they “can operate all day at atmospheric pressure” rather than at the low pressure required for operating a fluorescent lamp, for example, Eden says. In their journal paper, Eden, an IEEE Fellow, and his team describe microcavity plasma devices, “plasmas on a chip,” at atmospheric pressure. The Illinois researchers have developed tools for etching pyramidal cavities in silicon, coating their walls with a dielectric, surrounding the cavities with a second electrode, and sealing the system with a transparent window. The technology is adaptable to very thin and flexible displays that can be rolled up.

The microcavity approach also increases light output. “Because of the pressure, specific power loading is very high,” Eden says. “You are dissipating kilowatts of power per cubic centimeter, but you have very few cubic centimeters—nanoliters—per pixel.”

When will the technology be commercial? “It already is,” Eden says. “A former student of mine formed Caviton Inc., in Champaign, Ill., for environmental sensors. That’s the opposite of display, but microplasma helps make those sensors very light, portable, and sensitive.”

FOR MORE on the new display journal, visit http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=9425.