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SUMMARY:Designing Artificial Light-harvesting Arrays for Solar Cells - Pro
 fessor Anthony Harriman\, Newcastle University
DTSTART:20111027T130000Z
DTEND:20111027T140000Z
UID:TALK32436@talks.cam.ac.uk
CONTACT:Sian Bunnage
DESCRIPTION:Over the past decade there has been a renaissance of interest 
 in the processes by which electronic energy can be transported around an o
 rganized molecular array with minimal loss. The motivation for this resear
 ch stems from a desire to apply\, at a molecular level\, the lessons acqui
 red from our ever-deepening understanding of the natural light-harvesting 
 machinery that powers bacterial and green-plant photosynthesis and other b
 iological processes. A key requirement of all such functional units is the
  need to move the photonic energy to a site where chemical reactions are i
 nitiated. Paramount to the successful design of artificial  prototypes abl
 e to operate in this way is the logical positioning of individual units in
  a way that favours vectorial electronic energy transfer (EET) along the m
 olecular axis or by way of some other preferred pathway. An obvious\, and 
 indeed enviable\, extension for these materials is to devise a simple mean
 s by which the EET flow can be reversed\, while maintaining very high effi
 ciency. In designing new molecular systems for capable of performing speci
 fic EET it is necessary to establish a thorough understanding of the under
 lying mechanism and\, in particular\, to distinguish between through-space
  and bridge-mediated routes. The arrays need to retain the capacity to sen
 sitise solar cells\, such as those based on amorphous silicon\, in a benef
 icial manner.\n\nWe have examined many different molecular arrays built ar
 ound boron dipyrromethene dyes of varying conjugation length and of quite 
 different topology. The disparate spatial arrangements and the application
  of high pressure to curtail low-frequency torsional motions allow screeni
 ng of the EET mechanism in these systems. By combining many such arrays in
 to a coherent network\, it becomes possible to create artificial light-har
 vesting complexes with some modest degree of self regulatory function. Fur
 thermore\, the EET direction is easily switched by photochemical means\, i
 n certain cases. Of particular interest are those molecular systems where 
 EET occurs predominantly via Förster-type interactions since the theory c
 an be tested over short separations and in different media. \n
LOCATION:Unilever Lecture Theatre\, Department of Chemistry
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