期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 112, 期 41, 页码 E5560-E5566出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1512582112
关键词
photophysics; single-molecule spectroscopy; interchromophoric coupling; structure-property relations; organic electronics
资金
- European Research Council [305020]
- German Science Foundation for support through the Sonderforschungsbereich (SFB) [813]
- European Research Council (ERC) [305020] Funding Source: European Research Council (ERC)
An appealing definition of the term molecule arises from consideration of the nature of fluorescence, with discrete molecular entities emitting a stream of single photons. We address the question of how large a molecular object may become by growing deterministic aggregates from single conjugated polymer chains. Even particles containing dozens of individual chains still behave as single quantum emitters due to efficient excitation energy transfer, whereas the brightness is raised due to the increased absorption cross-section of the suprastructure. Excitation energy can delocalize between individual polymer chromophores in these aggregates by both coherent and incoherent coupling, which are differentiated by their distinct spectroscopic fingerprints. Coherent coupling is identified by a 10-fold increase in excited-state lifetime and a corresponding spectral red shift. Exciton quenching due to incoherent FRET becomes more significant as aggregate size increases, resulting in single-aggregate emission characterized by strong blinking. This mesoscale approach allows us to identify intermolecular interactions which do not exist in isolated chains and are inaccessible in bulk films where they are present but masked by disorder.
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