Differentiation between Shallow and Deep Charge Trap States on Single Poly(3-hexylthiophene) Chains through Fluorescence Photon Statistics.
Blinking of the photoluminescence (PL) emitted from individual conjugated polymer chains is one of the central observations made by single-molecule spectroscopy (SMS). Important information, for example regarding excitation energy transfer, can be extracted by evaluating dynamic quenching. However, the nature of trap states, which are responsible for PL quenching, often remains obscured. We present a detailed investigation of the photon statistics of single poly(3-hexylthiophene) (P3HT) chains obtained by SMS. The photon statistics provide a measure of the number and brightness of independently emitting areas on a single chain. These observables can be followed during blinking. A decrease in PL intensity is shown to be correlated with either 1) a decrease in the average brightness of the emitting sites; or 2) a decrease in the number of emitting regions. We attribute these phenomena to the formation of 1) shallow charge traps, which can weakly affect all emitting areas of a single chain at once; and 2) deep traps, which have a strong effect on small regions within the single chains.
CellNetworks Cluster und Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 267, 69210, Heidelberg, Germany.
Kristin S
KS
Grußmayer
Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany.
Florian
F
Steiner
Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany.
John M
JM
Lupton
CellNetworks Cluster und Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 267, 69210, Heidelberg, Germany. dirk-peter.herten@urz.uni-hd.de.
Dirk-Peter
DP
Herten
Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany. jan.vogelsang@physik.uni-regensburg.de.
Jan
J
Vogelsang
conjugated polymers; photoluminescence; photon statistics; photophysics; single-molecule spectroscopy