Summary
Energy migration, by which bound electron-hole pairs (i.e. singlet excitons) travel through an organic semiconductor before decaying, is at the heart of functioning optoelectronic devices such as solar cells. Designing materials with large singlet exciton diffusion lengths Ld would strongly benefit the efficiency of such devices. In this context, recent reports in highly ordered polymeric fibers and non-fullerene acceptor thin films of Ld largely exceeding the typical 10-20nm values call for a detailed microscopic picture going beyond the usual (hopping) models. Among others, a key missing ingredient in most modelling studies so far deals with the role of inter-molecular charge-transfer (CT) excitations. These have the potential to magnify the exciton dispersion at the band bottom or act as gateways for long-range energy migration, but could equally be detrimental to transport due to the formation of low-lying energy traps. In TECTESA, we aim at providing an in-depth mechanistic analysis of singlet exciton diffusion in organic molecular semiconductors in presence of CT configurations, highlighting namely their contrasting effects on the shape of the thermally accessible excitonic density of states and the coupling to the nuclear degrees of freedom. To reach this ambitious goal, we will: (i) develop and implement a universal transport formalism based on mixed classical-quantum non-adiabatic molecular dynamic simulations that explicitly accounts for CT excitations; (ii) explore how intermolecular CT configurations affect the nature and dynamics of singlet excitons in reduced models, through a broad range of physical situations (from superexchange to hybridization and trapping); and (iii) apply our newly developed approach to study energy migration in realistic, fully atomistic, models for N-heterotriangulene supramolecular fibers and non-fullerene Y6 molecular acceptors, where preliminary investigations seem to intimate the presence of low-lying CT pairs.
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| Web resources: | https://cordis.europa.eu/project/id/101106941 |
| Start date: | 01-10-2023 |
| End date: | 30-09-2025 |
| Total budget - Public funding: | - 175 920,00 Euro |
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Original description
Energy migration, by which bound electron-hole pairs (i.e. singlet excitons) travel through an organic semiconductor before decaying, is at the heart of functioning optoelectronic devices such as solar cells. Designing materials with large singlet exciton diffusion lengths Ld would strongly benefit the efficiency of such devices. In this context, recent reports in highly ordered polymeric fibers and non-fullerene acceptor thin films of Ld largely exceeding the typical 10-20nm values call for a detailed microscopic picture going beyond the usual (hopping) models. Among others, a key missing ingredient in most modelling studies so far deals with the role of inter-molecular charge-transfer (CT) excitations. These have the potential to magnify the exciton dispersion at the band bottom or act as gateways for long-range energy migration, but could equally be detrimental to transport due to the formation of low-lying energy traps. In TECTESA, we aim at providing an in-depth mechanistic analysis of singlet exciton diffusion in organic molecular semiconductors in presence of CT configurations, highlighting namely their contrasting effects on the shape of the thermally accessible excitonic density of states and the coupling to the nuclear degrees of freedom. To reach this ambitious goal, we will: (i) develop and implement a universal transport formalism based on mixed classical-quantum non-adiabatic molecular dynamic simulations that explicitly accounts for CT excitations; (ii) explore how intermolecular CT configurations affect the nature and dynamics of singlet excitons in reduced models, through a broad range of physical situations (from superexchange to hybridization and trapping); and (iii) apply our newly developed approach to study energy migration in realistic, fully atomistic, models for N-heterotriangulene supramolecular fibers and non-fullerene Y6 molecular acceptors, where preliminary investigations seem to intimate the presence of low-lying CT pairs.Status
SIGNEDCall topic
HORIZON-MSCA-2022-PF-01-01Update Date
31-07-2023
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