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 31, 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 31, 2014).

Share This




More Matter & Energy News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Britain Testing Driverless Cars on Roadways

Britain Testing Driverless Cars on Roadways

AP (July 30, 2014) — British officials said on Wednesday that driverless cars will be tested on roads in as many as three cities in a trial program set to begin in January. Officials said the tests will last up to three years. (July 30) Video provided by AP
Powered by NewsLook.com
Amid Drought, UCLA Sees Only Water

Amid Drought, UCLA Sees Only Water

AP (July 30, 2014) — A ruptured 93-year-old water main left the UCLA campus awash in 8 million gallons of water in the middle of California's worst drought in decades. (July 30) Video provided by AP
Powered by NewsLook.com
Smartphone Powered Paper Plane Debuts at Airshow

Smartphone Powered Paper Plane Debuts at Airshow

AP (July 30, 2014) — Smartphone powered paper airplane that was popular on crowdfunding website KickStarter makes its debut at Wisconsin airshow (July 30) Video provided by AP
Powered by NewsLook.com
U.K. To Allow Driverless Cars On Public Roads

U.K. To Allow Driverless Cars On Public Roads

Newsy (July 30, 2014) — Driverless cars could soon become a staple on U.K. city streets, as they're set to be introduced to a few cities in 2015. Video provided by Newsy
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