MOSCOW, Apr 5 Chemists from St. Petersburg State University (SPbGU) have synthesized an organic substance that can become the basis for creating organic light-emitting diodes that convert almost all consumed electricity into light, the Russian Science Foundation reports (RNF).
Organic Light Emitting Diodes, better known as OLEDs, are the most promising in the electronics industry. They are flexible, thin and have low power consumption. However, even they convert only 25% of the consumed electricity into light, the remaining three-quarters turn into heat, heating the device.
St Petersburg State University researchers have synthesized organometallic phosphors based on the so-called acyclic diaminocarbenes, which in the future will increase the efficiency of OLED light emission up to 100%.
In the molecule of the obtained substance, the platinum atom is connected to several organic fragments. Such complexes are well known to scientists due to their photoluminescence — the ability to glow when irradiated. They are used to make light-emitting polymers, as optical sensors, and as photocatalysts.
However, organometallics with acyclic diaminocarbenes were not previously used for the production of light sources, since there was no data on its ability to electroluminescence — the emission of light when a current is passed. In addition, organometallic phosphors were difficult to obtain: at the intermediate stage of assembly, transformations could occur with an organic fragment, due to which the result was not the substance that was intended.
Chemists from St Petersburg University used a promising synthesis method in which a metal-containing compound was initially formed, and the final modification of the organic fragment occurred directly inside this compound, which ensured the stability of the molecule during assembly. This made it possible to obtain a previously inaccessible type of light emitter with improved characteristics.
The synthesized phosphor glows green when a current passes through it. To conduct experiments, scientists have assembled models of organic light emitting diodes, using the substance as a light-emitting layer. The invention demonstrated high stability: the light remained constant even when the voltage changed, and the device did not overheat during operation.
Experimental samples showed a brightness 1.5 times higher than that of their closest analogues. It was also found that if you change the design of the LED, the glow becomes white. This makes it possible to use the phosphor in the manufacture of sources of both green and white light.
The results of the study, supported by a grant from the Russian Science Foundation, were published in the international scientific journal Dalton Transactions.