Femtosecond Optical Probes of Mesoscopic Materials for Photovoltaics

Lead Research Organisation: University of Oxford
Department Name: Oxford Physics

Abstract

There is growing evidence that our increasing consumption of fossil fuels is leading to a change in climate. Such predictions have brought new urgency to the development of clean, renewable sources of energy that will permit the current level of world economic growth to continue without damage to our ecosystem. Photovoltaic cells based on organic or organic/inorganic hybrid materials have shown rapid improvements over the past decade, comparing favourably with existing inorganic semiconductor technology on energy, scalability and cost associated with manufacture. The most promising materials for organic or hybrid photovoltaics are based on blends of two components at whose interface light-generated excitations dissociate into charges contributing to a photocurrent. Blend morphology on the meso-scale plays a crucial role in these systems, with efficient photovoltaic operation requiring both large interfacial area and existence of carrier percolation paths to the electrodes. The proposed work will establish how both aims can be achieved, using a powerful new combination of non-contact femtosecond time-resolved techniques to examine a range of novel mesoscopic blends. This methodology will allow the simultaneous examination of exciton diffusion and dissociation, charge-carrier generation, recombination and conductivity, providing direct clues to the optimisation of materials for photovoltaics. Collaborations with researchers working on making photovoltaic devices will ensure that knowledge gained from these non-contact material probes will directly feed into enhancing device performance. This combined approach will allow the UK's exceptionally high expertise in the area of organic electronics to contribute effectively to its current goal of reducing harmful greenhouse gas emission.

Publications

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Parkinson P (2014) Chromophores in Molecular Nanorings: When Is a Ring a Ring? in The journal of physical chemistry letters

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Schmid SA (2012) Energy transfer processes along a supramolecular chain of p-conjugated molecules. in Philosophical transactions. Series A, Mathematical, physical, and engineering sciences

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Sprafke JK (2011) Belt-shaped p-systems: relating geometry to electronic structure in a six-porphyrin nanoring. in Journal of the American Chemical Society

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Favereau L (2015) Six-Coordinate Zinc Porphyrins for Template-Directed Synthesis of Spiro-Fused Nanorings. in Journal of the American Chemical Society

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Parkinson P (2014) Ultrafast energy transfer in biomimetic multistrand nanorings. in Journal of the American Chemical Society

 
Description This research has allowed us to understand how to design better materials for next generation solar cells. We have used short light pulses to simulate solar light absorption in thin films of new molecular and hybrid solids, and then probed how electronic charges are generated. In this way we are able trace the whole process from light absorption to electrical current generation in new photovoltaic materials, which has given us clues on how to make better absorbers that give highly efficient, yet cheap solar cells.
Exploitation Route These findings are used by researchers in universities and industry to work towards next generation solar cells.
Sectors Chemicals

Education

Electronics

Energy

Manufacturing

including Industrial Biotechology

URL https://www-herz.physics.ox.ac.uk/research.html
 
Description EPSRC
Amount £578,131 (GBP)
Funding ID EP/J007161/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 03/2012 
End 02/2015