Organic computers are closer than ever

Scientists from the University of Moscow discovered a molecule that could help in the development of electronic devices based on organic materials

A team of researchers from the University of Moscow in collaboration with their colleagues from Germany (Polymer Research Institute in Dresden) managed to discover a molecule that they believe could benefit the development of electronic devices based on organic materials. The research findings have long been published in the scientific journalAdvanced materials. The researchers found that a derivative of the substance [3]-radialene (Wikipedia), A molecule known to science for thirty years, can be used to produce organic semiconductors. The scientists believe that their research achievement will make a significant contribution to the development of organic electronic components, and in particular, to the production of organic light-emitting diodes and new families of organic solar cells.

Organic, or "plastic-based" electronic components are a relatively new scientific field, which emerged into our world about twenty years ago. The purpose of this field is the development of electronic devices based on organic materials. At the same time, these types of devices are still inferior in their performance and stability compared to common electronic components based on silicon. Despite this, this type also has advantages - the brightness of the display, thinness, flexibility, transparency and most importantly - plastic electronic components are much cheaper than their silicon counterparts. The main applications of organic electronics include solar cells, which will be much cheaper than their common counterparts. In addition, organic electronic components could be used in the design of organic light emitting devices and innovative transistors.

The molecule in question is of the 'conducting agent' type, one that added to a semi-conducting polymer significantly increases its electrical conductivity. The use of conducting materials in the field of inorganic semiconductors has been prevalent for decades, however, this field is less developed in terms of organic conductors. Today, the most common materials are fluorine-based sealants. In combination with various organic semiconductors, these insulating materials are able to significantly increase the electrical conductivity, but not all the polymers commonly used today are suitable for such an application. Together with their colleagues, the researchers decided to design a completely new type of low molecular weight doping material for the organic semiconductor industry, the lead researcher explains. "And at this stage it was very important to choose a molecule that not only matches its energy levels, but, more importantly, can be properly mixed with the polymer, so that the contact between them will not create separate complexes that will result in the loss of activity of the finished polymer." The main contribution of the laboratory scientists as part of this research includes the study of the physics of the transition states, the physics of mixing these two components, that is, finding the most appropriate material in terms of its compatibility with the polymer.
And the researchers did find such a substance - a consequence of the substance [3]-radialene. It is a small flat molecule in which the carbon atoms are joined into a triangular structure. Among its other properties, this material has the most energetic LUMO (Lowest Unoccupied Molecular Orbital) energy level. The meaning of this characteristic states that only with a little energetic help the electrons can leave the semi-conducting polymer, and become free charges that increase the conductivity of the solidified material. This means that this material ([3]-radialene) becomes the strongest insulating material known today in the field of organic semiconductors.

The experiments conducted with the material, and which were verified by the results of quantum-mechanical calculations, show that the material mixes well with semi-conducting polymers and enables the electrical conductivity of the polymer to be increased tens or even hundreds of times. It turned out that when the concentration of the dopant in the polymer is up to 50%, no separation occurs, but the crystalline structure of the polymer changes significantly. This means that the molecules of the insulating material are integrated within the crystal lattice of the polymer and thereby create what is called a co-crystal. This configuration of the final material is one of the main reasons for the great efficiency of the new compound.
The new compound, and its history, belongs to a family of electroless organic conducting materials, explains the lead researcher. "Fluorine converters are known to be strong electron attractors from the central part of the molecule, a feature that increases the overall conductivity of the grafted polymer. In the current study, the chemical structure of the filler is completely different, and in fact, turns out to be even better. "The excellent mixing rate of our blocking material together with the polymer is the source of the excellent activity of our final material. This result could pave the way for the production of new solar cells and transistors with improved properties."