UH Collaboration with Universit茅 de Montr茅al Published in Nature Communications
葫芦影业 professor Eric Bittner (left) and Universit茅 de Montr茅al associate
professor Carlos Silva review data related to their theoretical model that may lead
to more efficient solar cells. The findings published in Nature Communications on
Jan. 29.A novel theoretical model may hold the key to methods for developing better materials
for solar cells.鈥═he model, developed by professors at the 葫芦影业 (UH)
and Universit茅 de Montr茅al, could lead to new solar cell materials made from improved
blends of semiconducting polymers and fullerenes.
Eric Bittner, a John and Rebecca Moores Professor of Chemistry and Physics in UH鈥檚 College of Natural Sciences and Mathematics, and Carlos Silva, an associate professor at the Universit茅 de Montr茅al and Canada Research Chair in Organic Semiconductor Materials, presented their theoretical model in the Jan. 29 issue of Nature Communications. Their paper is titled 鈥�.鈥�
鈥淪cientists don鈥檛 fully understand what is going on inside the materials that make up solar cells. We were trying to get at the fundamental photochemistry or photophysics that describes how these cells work,鈥� Bittner said.
Solar cells are made out of organic semiconductors 鈥� typically blends of materials. However, solar cells made of these materials have about 3 percent efficiency. Bittner added that the newer materials, the fullerene/polymer blends, only reach about 10 percent efficiency.
鈥淭here is a theoretical limit for the efficiency of the ideal solar cell 鈥� the Shockley-Queisser limit. The theory we published describes that we might be able to get above this theoretical limit by taking advantage of quantum mechanical effects,鈥� Bittner said. 鈥淏y understanding these effects and making use of them in the design of a solar cell, we believe you can improve efficiency.鈥�
Silva added, 鈥淚n polymeric semiconductors, where plastics form the active layer of solar cells, the electronic structure of the material is intimately correlated with the vibrational motion within the polymer chain. Quantum-mechanical effects due to such vibrational-electron coupling give rise to a plethora of interesting physical processes that can be controlled to optimize solar cell efficiencies by designing materials that best exploit them.鈥�
The idea for the model was born while Bittner was a Fulbright Canada Scholar and visiting professor at the Universit茅 de Montr茅al collaborating with Silva, an expert in the field of ultrafast laser spectroscopy and organic semiconductors.
Bittner says the benefit of their model is that it provides insight into what is happening in solar cell systems.
鈥淥ur theoretical model accomplishes things that you can鈥檛 get from a molecular model,鈥� he said. 鈥淚t is mostly a mathematical model that allows us to look at a much larger system with thousands of molecules. You can鈥檛 do ordinary quantum chemistry calculations on a system of that size.鈥�
The calculations have prompted a series of new experiments by Silva鈥檚 group to probe the outcomes predicted by their model.
Bittner and Silva鈥檚 next steps involve collaborations with researchers who are experts in making the polymers and fabricating solar cells.
The work at UH was funded by the Robert Welch Foundation and the National Science Foundation. The work in Canada was supported by the National Sciences and Engineering Research Council of Canada.
-- Kathy Major, College of Natural Sciences and Mathematics