Eric Bittner (left) and Carlos Silva reviewing data from their theoretical model that would develop more efficient solar cells.
MONTREAL, CANADA: Researchers from University of Houston and the University of Montreal, with their new theoretical model, have found the key that would develop better materials for solar cells. Eric Bittner, Holder of the Professorship of Chemistry, University of Houston and Carlos Silva, Associate Professor, University of Montreal, argued that their model could pave the way for the creation of new materials for solar cells from an improved polymers and fullerene semiconductor assembly.
The findings were described in an article titled “Noise-Induced Quantum Coherence Drives Photo-Generation Carrier Dynamics at Polymeric Semiconductor heterojunctions.”
“Scientists do not know exactly what is happening inside the materials that make up the solar cells. Our goal was to elucidate the fundamental photophysical or photochemical mechanisms that explain the functioning of these cells,” said Dr Bittner.
The solar cells are made of organic semiconductors - assemblies generally of different materials. However, these solar cells have an efficiency of about 3 per cent. Professor Bittner said that the latest materials, assemblies of fullerenes and polymers barely reach 10 per cent efficiency.
“The ideal solar cell has a theoretical efficiency limit: the limit of Shockley-Queisser. The theory that we are putting forward how it would be possible to exceed this theoretical limit by exploiting quantum mechanical effects. We believe it will be possible to improve the efficiency of solar cells when these effects have been understood and integrated into the design of the cells,” said Dr Bittner.
“In the semiconductor polymer, where the plastic form the active layer of solar cells, the electronic structure of the material is closely related to the vibratory motion within the polymer chain. The quantum mechanical effects associated with the coupling between the electrons and vibrations give rise to a plethora of interesting physical phenomena can be controlled to optimize the efficiency of solar cells, for example by designing materials that operate up these effects,” said Professor Silva.
Professor Bittner argues that the quality of the model lies in its ability to describe what happens inside a solar cell.
“Our theoretical model accomplishes things a molecular model could not do. It is first and foremost a mathematical model that allows us to model much larger systems, with thousands of molecules. You cannot make conventional quantum chemistry calculations with systems of this size,” said Silva.
© University of Montreal News