Publication Date:
2012-03-01
Description:
The electron-hole pair created via photon absorption in organic photoconversion systems must overcome the Coulomb attraction to achieve long-range charge separation. We show that this process is facilitated through the formation of excited, delocalized band states. In our experiments on organic photovoltaic cells, these states were accessed for a short time (〈1 picosecond) via infrared (IR) optical excitation of electron-hole pairs bound at the heterojunction. Atomistic modeling showed that the IR photons promote bound charge pairs to delocalized band states, similar to those formed just after singlet exciton dissociation, which indicates that such states act as the gateway for charge separation. Our results suggest that charge separation in efficient organic photoconversion systems occurs through hot-state charge delocalization rather than energy-gradient-driven intermolecular hopping.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bakulin, Artem A -- Rao, Akshay -- Pavelyev, Vlad G -- van Loosdrecht, Paul H M -- Pshenichnikov, Maxim S -- Niedzialek, Dorota -- Cornil, Jerome -- Beljonne, David -- Friend, Richard H -- New York, N.Y. -- Science. 2012 Mar 16;335(6074):1340-4. doi: 10.1126/science.1217745. Epub 2012 Feb 23.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Cavendish laboratory, University of Cambridge, Cambridge, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22362882" target="_blank"〉PubMed〈/a〉
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
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Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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