Conjugated “Molecular Wire” for Excitons
We have synthesized new conjugated, rigid rod oligomers of fluorene, F{sub n}(C{sub 60}){sub 2}, n = 4, 8, 12, and 16. These pure compounds have F{sub n} chains up to 140 {angstrom} long. The C{sub 60} groups covalently attached at both ends serve as traps for excitons created in the F{sub n} chains. Excitons created in the chains by photoexcitation reacted rapidly with the C{sub 60} groups with decays described well by the sum of two exponentials. Mean reaction times were 2.3, 5.5, and 10.4 ps for n = 8, 12, and 16. In F{sub 16}(C{sub 60}){sub 2}, the 10.4 ps reaction time was 40 times faster than that found in earlier reports on molecules of slightly longer length. The simplest possible model, that of one-dimensional diffusion of excitonic polarons that react whenever they encounter the end of a chain, fits the results to obtain diffusion coefficients. Deviations of those fits from the data may point to the need for alternative pictures or may just indicate that diffusion is not ideal. The definite lengths of these molecules enable a stringent test for theories. These results reveal that exciton transport can be much faster than previously believed, a finding that could, along with appropriate nanoassembly, enable new kinds of high-efficiency organic photovoltaics.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States). Laser Electron Accelerator Facility (LEAF)
- Sponsoring Organization:
- DOE - OFFICE OF SCIENCE
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 1020860
- Report Number(s):
- BNL-91325-2011-JA; R&D Project: CO-004; KC0301010; TRN: US201116%%886
- Journal Information:
- Journal of Physical Chemistry Letters, Vol. 1, Issue 9; ISSN 1948-7185
- Country of Publication:
- United States
- Language:
- English
Similar Records
Fullerene dications and trications as initiators in the gas-phase `ball-and-chain` polymerization of allene and propyne: Observation of a remarkable periodicity in chain growth with allene
Theory of optical transitions in conjugated polymers. I. Ideal systems