The photo is sourced from remstd.ru
One of the key elements of fibre optic devices used in IT and solar power industry are the electrodes conducting a light-generated electric current. According to earlier studies, optical devices, in which the electrodes transmit light, are more efficient than the ones with opaque electrodes. However, until recently, scientists were unable to create universal transparent electrodes. Such materials usually either do not conduct current well enough or are highly transparent only in a certain range (for example, in the near-infrared region of the spectrum).
The scientists of the Institute of Automation and Control Processes of the Far Eastern Branch of the RAS tried to solve this problem by developing the electrodes based on calcium digermanide, i.e. a compound consisting of alternating two-dimensional layers of calcium and germanium atoms. The authors of the study grew thin (tens of thousands of times thinner than a millimetre) films of this material by depositing calcium and germanium in a vacuum chamber on an aluminum oxide substrate and subjecting them to the temperature treatment at 750−850°C.
To evaluate transparency of the obtained samples, the researchers let light of different wavelengths pass through them. The material turned out to be able to transmit up to 78% of radiation, but mainly in the infrared range from 1,000 to 4,000 nanometres. To improve the electrodes performance, the physicists decided to use a laser to make small square holes in the film so that a checkered pattern would appear on the surface of the material. Perforation increased the electrode transparency up to 90%, especially in the spectrum visible region. As a result, the electrode became transparent in a wider range of light wavelengths: from 400 to 7,000 nanometres, while the treatment did not affect significantly its electrical characteristics.
“Laser processing results in formation of a completely transparent micro-holes, and the higher their density, the higher the overall transparency of the patterned area. At the same time, excessive perforation usually raises the electrical resistance of the film, the second important characteristic of any transparent conductive electrode. The higher the resistance, the greater the losses at the current flow through the electrode. In this regard, a balance is required between optical transmission and electrical conductivity,” the Russian Science Foundation quotes Alexander Kuchmizhak, PhD in physics and math, one of the authors of the study.
