TY - JOUR
T1 - Near-Infrared Absorption Features of Triplet-Pair States Assigned by Photoinduced-Absorption-Detected Magnetic Resonance
AU - Dill, Ryan D.
AU - Joshi, Gajadhar
AU - Thorley, Karl J.
AU - Anthony, John E.
AU - Fluegel, Brian
AU - Johnson, Justin C.
AU - Reid, Obadiah G.
N1 - Publisher Copyright:
© 2023 The Authors. Published by American Chemical Society.
PY - 2023/3/9
Y1 - 2023/3/9
N2 - Singlet fission proceeds through a manifold of triplet-pair states that are exceedingly difficult to distinguish spectroscopically. Here, we introduce a new implementation of photoinduced-absorption-detected magnetic resonance (PADMR) and use it to understand the excited-state absorption spectrum of a tri-2-pentylsilylethynyl pentadithiophene (TSPS-PDT) film. These experiments allow us to directly correlate magnetic transitions driven by RF with electronic transitions in the visible and near-infrared spectrum with high sensitivity. We find that the new near-infrared excited-state transitions that arise in thin films of TSPS-PDT are correlated with the magnetic transitions of T1, not 5TT. Thus, we assign these features to the excited-state absorption of 1TT, which is depleted when T1 states are driven to a spin configuration that forbids subsequent fusion. These results clarify the disputed origin of triplet-associated near-infrared absorption features in singlet-fission materials and demonstrate an incisive general purpose tool for studying the evolution of high-spin excited states.
AB - Singlet fission proceeds through a manifold of triplet-pair states that are exceedingly difficult to distinguish spectroscopically. Here, we introduce a new implementation of photoinduced-absorption-detected magnetic resonance (PADMR) and use it to understand the excited-state absorption spectrum of a tri-2-pentylsilylethynyl pentadithiophene (TSPS-PDT) film. These experiments allow us to directly correlate magnetic transitions driven by RF with electronic transitions in the visible and near-infrared spectrum with high sensitivity. We find that the new near-infrared excited-state transitions that arise in thin films of TSPS-PDT are correlated with the magnetic transitions of T1, not 5TT. Thus, we assign these features to the excited-state absorption of 1TT, which is depleted when T1 states are driven to a spin configuration that forbids subsequent fusion. These results clarify the disputed origin of triplet-associated near-infrared absorption features in singlet-fission materials and demonstrate an incisive general purpose tool for studying the evolution of high-spin excited states.
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U2 - 10.1021/acs.jpclett.2c03665
DO - 10.1021/acs.jpclett.2c03665
M3 - Article
C2 - 36848633
AN - SCOPUS:85149126195
VL - 14
SP - 2387
EP - 2394
JO - Journal of Physical Chemistry Letters
JF - Journal of Physical Chemistry Letters
IS - 9
ER -