TY - JOUR
T1 - Varying the Interpentacene Electronic Coupling to Tune Singlet Fission
AU - Papadopoulos, Ilias
AU - Zirzlmeier, Johannes
AU - Hetzer, Constantin
AU - Bae, Youn J.
AU - Krzyaniak, Matthew D.
AU - Wasielewski, Michael R
AU - Clark, Timothy
AU - Tykwinski, Rik R.
AU - Guldi, Dirk M.
PY - 2019/4/17
Y1 - 2019/4/17
N2 -
We have designed and used four different spacers, denoted A-D, to connect two pentacenes and to probe the impact of intramolecular forces on the modulation of pentacene-pentacene interactions and, in turn, on the key steps in singlet fission (SF), that is, the
1
(S
1
S
0
)-to-
1
(T
1
T
1
) as well as
1
(T
1
T
1
)-to-
5
(T
1
T
1
) transitions by means of transient absorption and electron paramagnetic resonance measurements. In terms of the
1
(S
1
S
0
)-to-
1
(T
1
T
1
) transition, a superexchange mechanism, that is, coupling to a higher-lying CT state to generate a virtual intermediate, enables rapid SF in A-D. Sizeable electronic coupling in A and B opens, on one hand, an additional pathway, that is, the population of a real intermediate, and changes, on the other hand, the mechanism to that of hopping. In turn, A and B feature much higher
1
(T
1
T
1
) quantum yields than C and D, with a maximum value of 162% for A. In terms of the
1
(T
1
T
1
)-to-
5
(T
1
T
1
) transition, the sizable electronic coupling in A and B is counterproductive, and C and D give rise to higher
5
(T
1
T
1
)-to-(T
1
+ T
1
) quantum yields than A and B, with a maximum value of 85% for D.
AB -
We have designed and used four different spacers, denoted A-D, to connect two pentacenes and to probe the impact of intramolecular forces on the modulation of pentacene-pentacene interactions and, in turn, on the key steps in singlet fission (SF), that is, the
1
(S
1
S
0
)-to-
1
(T
1
T
1
) as well as
1
(T
1
T
1
)-to-
5
(T
1
T
1
) transitions by means of transient absorption and electron paramagnetic resonance measurements. In terms of the
1
(S
1
S
0
)-to-
1
(T
1
T
1
) transition, a superexchange mechanism, that is, coupling to a higher-lying CT state to generate a virtual intermediate, enables rapid SF in A-D. Sizeable electronic coupling in A and B opens, on one hand, an additional pathway, that is, the population of a real intermediate, and changes, on the other hand, the mechanism to that of hopping. In turn, A and B feature much higher
1
(T
1
T
1
) quantum yields than C and D, with a maximum value of 162% for A. In terms of the
1
(T
1
T
1
)-to-
5
(T
1
T
1
) transition, the sizable electronic coupling in A and B is counterproductive, and C and D give rise to higher
5
(T
1
T
1
)-to-(T
1
+ T
1
) quantum yields than A and B, with a maximum value of 85% for D.
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U2 - 10.1021/jacs.8b09510
DO - 10.1021/jacs.8b09510
M3 - Article
C2 - 30854854
AN - SCOPUS:85064573691
VL - 141
SP - 6191
EP - 6203
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 15
ER -