The photo is sourced from minobrnauki.gov.ru

The Graetzel cell, which is an alternative to silicon panels, includes five main elements: a glass anode coated with a transparent and conductive tin oxide layer; a mesoporous layer of titanium dioxide deposited on the anode generating electrons from its interaction with light; a layer of dye absorbed by the anode, which gives the latter photosensitivity (this is actually the process of sensitisation); an electrolyte that conducts electricity and contains a redox mediator to restore the dye; and, finally, a cathode made of a layer of the platinum deposited on glass to collect electrons.

As a rule, the sensitiser’s role is performed by the dyes based on ruthenium compounds, a silver-white transition metal belonging to the platinum group. However, the use of such dyes makes practically impossible commercialisation of the cells due to ruthenium high cost. Therefore, we can use, as an alternative, cheaper metal-free dyes whose molecules consist of fragments with excess (a donor fragment – D) and low (an acceptor fragment – A) electron density, which are bound by a π-electron bridge. This is the dye with its characteristic D-π-A architecture that was tested by the scientists from the MIET and RAS various institutes.

“The sensitised solar cells are based on new metal-free dyes with D-π-A architecture. A high degree of sunlight absorption by dyes is provided by a developed system of π-conjugation in molecules due to an efficient intramolecular charge transfer from the donor to the acceptor part of the dye. Due to a set of effective and reliable approaches to the synthesis of metal-free dyes, their cost is obviously lower than the one of similar commercial functional materials” the Ministry of Science and Higher Education of the Russian Federation quotes, in its press release, Alexander Steparuk, a junior researcher at the Postovsky Institute of Organic Synthesis, the Ural Branch of the RAS.

The researchers made and tested prototype sensitised panels. “For example, they measured the efficiency and the output electrical power under the standard illumination conditions “AM 1.5”, which corresponds to the solar radiation intensity on the Earth’s surface when the Sun is at a 45 ° angle to the horizon,” the Ministry of Education and Science quotes Peter Lazarenko, a MIET senior researcher. “The influence of the structural fragments of the obtained dyes on the quantum efficiency of the elements was determined when they were exposed to monochromatic radiation and under a permanent control of temperature and humidity. Thus, we have confirmed suitability of our development for operation under real meteorological conditions.”

We can vary the shade of translucent cells by changing the structure of dyes, which makes possible assembling of a multi-coloured mosaic from the sensitised panels, which is especially important in the building exterior design. These advantages are supposed to make it easier finding of investors able to implement the assembly of elements in the production environment, and then commercialise the development.