Selectively blocking undesirable exciton transfer pathways is crucial for utilizing exciton conversion processes that involve participation of multiple chromophores. This is particularly challenging for solid-state systems, where the chromophores are fixed in close proximity. For instance, the low efficiency of solid-state triplet–triplet upconversion calls for inhibiting the parasitic singlet back-transfer without blocking the flow of triplet excitons. Here, we present a reticular chemistry strategy that inhibits the resonance energy transfer of singlet excitons. Within a pillared layer metal–organic framework (MOF), pyrene-based singlet donors are situated perpendicular to porphyrin-based acceptors. High resolution transmission electron microscopy and electron diffraction enable direct visualization of the structural relationship between donor and acceptor (D–A) chromophores within the MOF. Time-resolved photoluminescence measurements reveal that the structural and symmetry features of the MOF reduce the donor-to-acceptor singlet transfer efficiency to less than 36% compared to around 96% in the control sample, where the relative orientation of the donor and acceptor chromophores cannot be controlled.
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Measuring the impact of spin-triplet exciton orientation on photocurrent in an organic transistor
The dynamics of triplet and singlet exciton populations in organic semiconductors offer interesting possibilities in improving optical device efficiency, while also attracting interest for future applications as manipulable states for quantum-state based computing. For technological applications, transduction of the exciton state is essential, thus detailed information on how the exciton dynamics affect device outputs is required. In this study, we measure the magnetic field response of the photocurrent in organic transistors to investigate the electrical signal resulting from singlet–triplet exciton dynamics. We find that controlling the orientation of the magnetic dipole orientation of the triplet by varying both the magnitude and orientation of the magnetic field with respect to single crystal axes in anti -2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene ( a diF TES ADT) allows us to manipulate the amount of current detected as a result of singlet fission.
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- Award ID(s):
- 1849213
- PAR ID:
- 10319211
- Date Published:
- Journal Name:
- Journal of Materials Chemistry C
- Volume:
- 9
- Issue:
- 35
- ISSN:
- 2050-7526
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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