Electronic Processes at Organic Semiconductor Heterojunctions: The Mechanism of Exciton Dissociation in Semicrystalline Solid‐State Microstructures

Paquin, Francis; Latini, Gianluca; Sakowicz, M.; Karsenti, Paul‐Ludovic; Wang, Linjun; Beljonne, David; Stingelin, Natalie; Silva, Carlos

doi:10.1002/9783527654949.ch11

Cited by 1 publication

(2 citation statements)

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“…[5] The tendency of Haggregates to form polarons stems largely from their polymorphic nature with distributed interfaces between ordered and disordered zones. [9] Unlike J-aggregates, no fractionation occurs during their formation meaning leading to a large amount of amorphous chains within the nanofiber and smaller aggregated regions with less conformational order (i.e., planarity). As demonstrated by Paquin et al, these interfaces facilitate charge separation which likely occurs on much faster timescales than triplet formation.…”

Section: Singlet Exciton Pl Quenching By Tripletsmentioning

confidence: 99%

“…As demonstrated by Paquin et al, these interfaces facilitate charge separation which likely occurs on much faster timescales than triplet formation. [9] The significantly larger triplet populations in J-aggregates are believed to originate from recombination of weakly correlated polaron pairs. Importantly, singlet-triplet splitting for these species should be much smaller than encountered in H-aggregates due to lower exchange energies.…”

Section: Singlet Exciton Pl Quenching By Tripletsmentioning

confidence: 99%

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Exciton and polaron interactions in self-assembled conjugated polymer aggregates

2015

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We study exciton coupling and interconversion between neutral and charged states of different spin in pi-stacked conjugated polymer aggregates. Rigorous self-assembly approaches are used to prepare aggregate nanofibers that permit reliable control of polymer chain conformational and packing (intra-and interchain) order within these structures. Exciton coupling can be tuned between the H-and J-aggregate limits, which has important implications for determining the fates of excitons and polarons. Single molecule intensity modulation spectroscopy was performed on individual nanofibers and large quenching depths of emissive singlet excitons by triplets are found in J-aggregate type structures. We propose that high intrachain order leads to exciton delocalization that effectively lowers singlet-triplet energy splittings thus increasing triplet yields. Exciton-polaron and polaron-polaron interactions are next investigated in both H-and J-type nanofibers where polarons are injected by charge transfer doping. We find that the enhanced intrachain order of J-aggregates enables efficient intrachain polaron transport and leads to significantly larger doping efficiencies than less ordered H-aggregates. As polaron densities increase, signatures of spin-spin interactions between polarons on adjacent chains become appreciable leading to the formation of a spinless bipolaron. Overall, these studies demonstrate the potential for controlling and directing exciton and polaron interactions via tuning of subtle intra-and interchain ordering characteristics of aggregates, which could benefit various polymeric optoelectronic applications.

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Section: Singlet Exciton Pl Quenching By Tripletsmentioning

confidence: 99%

Section: Singlet Exciton Pl Quenching By Tripletsmentioning

confidence: 99%