The LED – How LEDs work? – English version
International Research Team Demonstrates Gallium Nitride LED Color Tuning Technology by Changing the Time Sequence of Current Injection.
In existing displays, all colors are generated by three separate LEDs. By controlling closely spaced red, green and blue LEDs, the desired emission color is achieved. Scientists have shown that the same effect can be achieved with a single device.
To do this, they used a gallium nitride LED doped with one rare earth europium ion. By controlling the density and duty cycle of the pulsed current, the researchers showed that different colors can be obtained by combining two different excitation states of the Eu3 + ion (~ 620 nm and ~ 545 nm) with radiation from GaN (~ 430 nm).
Top row: Gallium nitride LED with europium ion, which can be adjusted to the red / yellow range. Middle and Bottom Rows: Same LED with Si / Mg switched on to add blue.
The activation of multiple excited states is not limited to the GaN: Eu system. The technology could open up a new field of application for radiation control impurities in semiconductors with a simple energy adjustment.
The use of such LEDs will increase the pixel density of the displays and achieve richer colors..
Another promising direction for improving the display is the use of quantum dots.. Recently engineers created «minifactory» for the production of quantum dots of the entire spectrum.
text: Ilya Bauer, photo: blogspot