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Title: An insight into non-emissive excited states in conjugated polymers

Journal Article · · Nature Communications
DOI: https://doi.org/10.1038/ncomms9246 · OSTI ID:1459344

Conjugated polymers in the solid state usually exhibit low fluorescence quantum yields, which limit their applications in many areas such as light-emitting diodes. Despite considerable research efforts, the underlying mechanism still remains controversial and elusive. Here, the nature and properties of excited states in the archetypal polythiophene are investigated via aggregates suspended in solvents with different dielectric constants (ε). In relatively polar solvents (ε>~ 3), the aggregates exhibit a low fluorescence quantum yield (QY) of 2–5%, similar to bulk films, however, in relatively nonpolar solvents (ε<~ 3) they demonstrate much higher fluorescence QY up to 20–30%. A series of mixed quantum-classical atomistic simulations illustrate that dielectric induced stabilization of nonradiative charge-transfer (CT) type states can lead to similar drastic reduction in fluorescence QY as seen experimentally. In conclusion, fluorescence lifetime measurement reveals that the CT-type states exist as a competitive channel of the formation of emissive exciton-type states.

Research Organization:
Energy Frontier Research Centers (EFRC) (United States). Understanding Charge Separation and Transfer at Interfaces in Energy Materials (CST); Univ. of Texas at Austin, Austin, TX (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Grant/Contract Number:
SC0001091
OSTI ID:
1459344
Journal Information:
Nature Communications, Journal Name: Nature Communications Journal Issue: 1 Vol. 6; ISSN 2041-1723
Publisher:
Nature Publishing GroupCopyright Statement
Country of Publication:
United States
Language:
English

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