A breakthrough in night vision technology

Jan 30, 2007 12:07 GMT  ·  By

Scientists are increasingly incorporating organic molecules into devices as many are proven to hide amazing properties.

Amongst the fields experiencing this is the conventional inorganic semiconductor electronics.

Now, flexible displays, large illuminated displays, or flat-panel displays can be realized from organic light-emitting diodes (OLEDs).

If till now OLEDs have been developed almost exclusively focusing on the visible light spectrum, recently, an American research team led by Mark E. Thompson has approached the matter of OLEDs that emit infrared light.

These devices would be a breakthrough in night-vision technology.

The complex team from the University of Southern California, Princeton University, the University of Michigan, and the Universal Display Corporation announced that their research employed a phosphorescent platinum porphyrin complex utilized as a doping agent.

The structure of an OLED is made up of a thin, glowing component composed of organic, semiconducting materials imitating an inorganic light-emitting diode (LED) and between the two electrodes and the additional layers, there's a dye-containing emission layer.

Applying power, the cathode discharges electrons into the emission layer while the anode sucks electrons.

When the emission layer turns to its ground state, energy is expelled in the form of light.

Previous techniques were used as emission layers in OLEDs fluorescent dyes, but the new phosphorescent molecules are supposed to lead to much more efficient OLEDs.

Phosphorescent molecules expel photons for longer periods of time as they cannot turn off their ground state too easy.

The color of the emitted light is determined by the energy difference between turn on and turn off, linked to the precise structure of the dye molecule.

The porphyrins employed in the platinum-porphyrin complex are natural organic compounds found in substances like hemoglobin and chlorophyll.

The framework of a porphyrin molecule is made up of four nitrogen-containing five-member rings connected into one large cyclic structure.

The metal atom, platinum in this research, is situated in the center of this ring.

The team modeled the molecular structure so that the new porphyrin expels light in the infrared region of the spectrum as desired for a night vision OLED.