Featured Research

from universities, journals, and other organizations

Light-emitting Diodes For Night-vision Displays

Date:
January 24, 2007
Source:
John Wiley & Sons, Inc.
Summary:
American researchers led by Mark E. Thompson have developed OLEDs that emit infrared light. Such diodes are needed for displays meant to be viewed through night-vision devices. The research team from the University of Southern California, Princeton University and the University of Michigan, as well as the Universal Display Corporation divulged the secret behind their success in the journal Angewandte Chemie: a phosphorescent platinum porphyrin complex used as a doping agent.

More and more, conventional inorganic semiconductor electronics are being complemented with organic components. For example, flexible displays, large illuminated displays, or flat-panel displays can be made from organic light-emitting diodes (OLEDs).

Whereas research into OLEDs has thus far focused almost exclusively on those that emit light in the visible part of the spectrum, American researchers led by Mark E. Thompson have worked on OLEDs that emit infrared light. Such diodes are needed for displays meant to be viewed through night-vision devices. The research team from the University of Southern California, Princeton University, and the University of Michigan, as well as the Universal Display Corporation divulged the secret behind their success in the journal Angewandte Chemie: a phosphorescent platinum porphyrin complex used as a doping agent.

An OLED is a thin, glowing component made of organic, semiconducting materials whose structure resembles that of an inorganic light-emitting diode (LED). Between two electrodes, as well as additional layers, is a dye-containing emission layer. When a voltage is applied, the cathode pumps electrons into the emission layer while the anode pumps in electron “holes”. This puts the dye into an excited state. When the dye molecules return to their ground state, energy is released in the form of light. Previously, the emission layers in OLEDs were doped with fluorescent dyes. Phosphorescent dopants are expected to result in significantly more efficient OLEDs. Phosphorescent dyes emit light for a longer period of time, because they are “trapped” in their excited state and cannot return to their ground state as easily.

The color of the light emitted depends on the difference in energy between the two energy levels. This in turn depends on the precise structure of the dye molecule. Thompson and his team chose to use a platinum porphyrin complex as their phosphorescent doping agent. Porphyrins can be found in such substances as hemoglobin and chlorophyll. The framework of a porphyrin complex consists of four nitrogen-containing five-membered rings that are connected into one large cyclic structure. The metal atom—in this case a platinum atom—sits in the center of this ring. The researchers tweaked the other details of the molecular structure so that their saddle-shaped porphyrin emits light in the infrared region of the spectrum; and very efficiently too, when it is included in the emission layer of an OLED.


Story Source:

The above story is based on materials provided by John Wiley & Sons, Inc.. Note: Materials may be edited for content and length.


Cite This Page:

John Wiley & Sons, Inc.. "Light-emitting Diodes For Night-vision Displays." ScienceDaily. ScienceDaily, 24 January 2007. <www.sciencedaily.com/releases/2007/01/070123111051.htm>.
John Wiley & Sons, Inc.. (2007, January 24). Light-emitting Diodes For Night-vision Displays. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2007/01/070123111051.htm
John Wiley & Sons, Inc.. "Light-emitting Diodes For Night-vision Displays." ScienceDaily. www.sciencedaily.com/releases/2007/01/070123111051.htm (accessed July 28, 2014).

Share This




More Matter & Energy News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Europe's Highest Train Turns 80 in French Pyrenees

Europe's Highest Train Turns 80 in French Pyrenees

AFP (July 25, 2014) — Europe's highest train, the little train of Artouste in the French Pyrenees, celebrates its 80th birthday. Duration: 01:05 Video provided by AFP
Powered by NewsLook.com
TSA Administrator on Politics and Flight Bans

TSA Administrator on Politics and Flight Bans

AP (July 24, 2014) — TSA administrator, John Pistole's took part in the Aspen Security Forum 2014, where he answered questions on lifting of the ban on flights into Israel's Tel Aviv airport and whether politics played a role in lifting the ban. (July 24) Video provided by AP
Powered by NewsLook.com
Creative Makeovers for Ugly Cellphone Towers

Creative Makeovers for Ugly Cellphone Towers

AP (July 24, 2014) — Mobile phone companies and communities across the country are going to new lengths to disguise those unsightly cellphone towers. From a church bell tower to a flagpole, even a pencil, some towers are trying to make a point. (July 24) Video provided by AP
Powered by NewsLook.com
Algonquin Power Goes Activist on Its Target Gas Natural

Algonquin Power Goes Activist on Its Target Gas Natural

TheStreet (July 23, 2014) — When The Deal's Amanda Levin exclusively reported that Gas Natural had been talking to potential suitors, the Ohio company responded with a flat denial, claiming its board had not talked to anyone about a possible sale. Lo and behold, Canadian utility Algonquin Power and Utilities not only had approached the company, but it did it three times. Its last offer was for $13 per share as Gas Natural's was trading at a 60-day moving average of about $12.50 per share. Now Algonquin, which has a 4.9% stake in Gas Natural, has taken its case to shareholders, calling on them to back its proposals or, possibly, a change in the target's board. Video provided by TheStreet
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins