3 research outputs found
Direct Observation of a Charge-Transfer State Preceding High-Yield Singlet Fission in Terrylenediimide Thin Films
Singlet
exciton fission (SF) in organic chromophore assemblies
results in the conversion of one singlet exciton (S<sub>1</sub>) into
two triplet excitons (T<sub>1</sub>), provided that the overall process
is exoergic, i.e., <i>E</i>(S<sub>1</sub>) > 2<i>E</i>(T<sub>1</sub>). We report on SF in thin polycrystalline
films of
two terrylene-3,4:11,12-bisÂ(dicarboximide) (TDI) derivatives <b>1</b> and <b>2</b>, which crystallize into two distinct
Ï€-stacked structures. Femtosecond transient absorption spectroscopy
(fsTA) reveals a charge-transfer state preceding a 190% T<sub>1</sub> yield in films of <b>1</b>, where the π-stacked TDI
molecules are rotated by 23° along an axis perpendicular to their
Ï€ systems. In contrast, when the TDI molecules are slip-stacked
along their N–N axes in films of <b>2</b>, fsTA shows
excimer formation, followed by a 50% T<sub>1</sub> yield
Direct Observation of a Charge-Transfer State Preceding High-Yield Singlet Fission in Terrylenediimide Thin Films
Singlet
exciton fission (SF) in organic chromophore assemblies
results in the conversion of one singlet exciton (S<sub>1</sub>) into
two triplet excitons (T<sub>1</sub>), provided that the overall process
is exoergic, i.e., <i>E</i>(S<sub>1</sub>) > 2<i>E</i>(T<sub>1</sub>). We report on SF in thin polycrystalline
films of
two terrylene-3,4:11,12-bisÂ(dicarboximide) (TDI) derivatives <b>1</b> and <b>2</b>, which crystallize into two distinct
Ï€-stacked structures. Femtosecond transient absorption spectroscopy
(fsTA) reveals a charge-transfer state preceding a 190% T<sub>1</sub> yield in films of <b>1</b>, where the π-stacked TDI
molecules are rotated by 23° along an axis perpendicular to their
Ï€ systems. In contrast, when the TDI molecules are slip-stacked
along their N–N axes in films of <b>2</b>, fsTA shows
excimer formation, followed by a 50% T<sub>1</sub> yield
Direct Observation of a Charge-Transfer State Preceding High-Yield Singlet Fission in Terrylenediimide Thin Films
Singlet
exciton fission (SF) in organic chromophore assemblies
results in the conversion of one singlet exciton (S<sub>1</sub>) into
two triplet excitons (T<sub>1</sub>), provided that the overall process
is exoergic, i.e., <i>E</i>(S<sub>1</sub>) > 2<i>E</i>(T<sub>1</sub>). We report on SF in thin polycrystalline
films of
two terrylene-3,4:11,12-bisÂ(dicarboximide) (TDI) derivatives <b>1</b> and <b>2</b>, which crystallize into two distinct
Ï€-stacked structures. Femtosecond transient absorption spectroscopy
(fsTA) reveals a charge-transfer state preceding a 190% T<sub>1</sub> yield in films of <b>1</b>, where the π-stacked TDI
molecules are rotated by 23° along an axis perpendicular to their
Ï€ systems. In contrast, when the TDI molecules are slip-stacked
along their N–N axes in films of <b>2</b>, fsTA shows
excimer formation, followed by a 50% T<sub>1</sub> yield