|
Electroluminescent
polymers
For the last 20 years we have known how to synthesise metallic or
semiconducting polymers. However, until recently these materials
had found few applications. The recent discovery of an intense electroluminescence
in a few of these polymers, and in certain organometallic molecules,
will probably accelerate their development due to the great promise
shown by new applications in display technology (TV and computer
screens) and lighting.
The simplest electroluminescent device is a diode. To manufacture
a diode, three very thin layers are successively deposited on a
sheet of glass. The first constitutes the anode and consists of
a transparent semiconductor oxide. The second is a layer of an electroluminescent
substance (polymer, organometallic molecules). The last acts as
the cathode and is made of a very electro-positive metal such as calcium.
When an electrical field is applied, the ions meet in the electroluminescent
layer. Here they combine and emit a photon which escapes throuh
the layer of semiconductor oxide and the sheet of glass.
|
 |
