MOSCOW, Jul 18— . Scientists from the N. F. Katanov Khakass State University (KhSU, a member of the Yenisei Siberia Research and Education Center) have proposed a new approach to the creation of LEDs, follows from a paper published in the journal Fundamental Problems of Modern Materials Science.
LEDs are semiconductor devices that convert electrical energy into light. Today it is a key element of screens, lighting fixtures and many other systems.Specialists from KhSU have shown that the addition of silver nanoparticles synthesized by a special method will significantly increase the characteristics of LEDs of any type.
As the authors of the study explain, the nanoparticles with a special geometry they proposed activate the surface plasmon resonance (SPR) effect in LEDs. This phenomenon consists in the amplification of electromagnetic radiation at the boundary between a noble metal and a dielectric: light falling on the junction of a silver or gold particle with a non-conductive material is reflected with a multiply increasing intensity.
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“Our work has shown that surface plasmon resonance can not only significantly increase the lifetime of an LED, but also increase its luminous efficiency many times over. To achieve these effects, it is necessary to introduce gold or silver nanostructures with various complex types of symmetry into the LED,” said the head of the Nanophysics laboratory. KSU Professor Yuri Gafner.
The SPR intensity depends on many factors, the main of which are the shape and size of the plasmonic nanoparticle. According to the scientists, silver is the most suitable material for creating such particles, since it is cheaper than other noble metals and is easier to nanostructure.
«By varying the size, shape and internal structure of a plasmonic particle, great progress can be made both in improving existing versions of LEDs and in creating new ones. In order to determine the most advantageous geometry and structure, we used molecular dynamics methods,» Gafner added.
Plasmonic nanoparticles differ from ordinary nanoparticles in the absence of an internal structure characteristic of the bulk form of a substance. To obtain such nanosilver, it is necessary to destroy the crystal lattice of an ordinary particle with a diameter of less than two nanometers by heating until melting, and then cool it sharply. A slight heating of this structure makes it possible to obtain plasmonic particles with given symmetry parameters. As the researchers emphasize, this synthesis technique was developed and applied for the first time in the world.
«The symmetry of the particles affects the amount of scattering and absorption of a light wave. The greatest effect is produced by highly symmetrical figures — cubes, octahedrons, and so on, up to «nanostars» with a large number of sharp «rays». The maximum possible number of sharp corners of the figure provides a high sink of electrons, giving an increase in luminosity,» Gafner explained.
The authors note that their research is fundamental. Experimental verification and implementation of the obtained data into the technological process is already being carried out on the basis of some universities, for example, at the National Research University «MIET».
The work was supported by the Russian Science Foundation, grant No. industry carbonization. The REC includes nine universities, five research institutes and 14 industrial enterprises.