Excited-state engineering in molecular aggregates |
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| John Lupton | |
| Universität Regensburg | |
| Pi-conjugated organic molecules offer unique opportunities for tuning the level ordering and dynamics of excited states. For example, raising the excited-state lifetime can be beneficial to promoting exciton migration and dissociation, which constitute necessary steps in photovoltaic devices. There are two routes to tuning excited-state lifetimes: through dipolar or exchange interactions.
Control of dipolar interactions within a molecular aggregate has been shown to raise the excited state lifetime by over two orders of magnitude, thus dramatically enhancing exciton migration [1]. Alternatively, the interplay between singlet and triplet levels can be tuned in a linear molecular aggregate, a conjugated co-polymer, by controlling the relative localisation of the two excitations [2]. This tunable exchange gap directly impacts on excited-state dynamics. Finally, local hyperfine fields can be modified to control the coherent light-matter interaction from a molecular level upwards [3]. [1] Chaudhuri et al., Nano Lett. 11, 488 (2011) |