Varying the Interpentacene Electronic Coupling to Tune Singlet Fission
| Autor: | Timothy Clark, Johannes Zirzlmeier, Youn Jue Bae, Constantin Hetzer, Michael R. Wasielewski, Ilias Papadopoulos, Matthew D. Krzyaniak, Rik R. Tykwinski, Dirk M. Guldi |
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| Rok vydání: | 2019 |
| Předmět: |
Coupling
education.field_of_study Chemistry Population General Chemistry 010402 general chemistry 01 natural sciences Biochemistry Molecular physics Catalysis 0104 chemical sciences law.invention Colloid and Surface Chemistry Superexchange law Intramolecular force Singlet fission Ultrafast laser spectroscopy Electron paramagnetic resonance education Quantum |
| Zdroj: | Journal of the American Chemical Society. 141(15) |
| ISSN: | 1520-5126 |
| Popis: | 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(S1S0)-to-1(T1T1) as well as 1(T1T1)-to-5(T1T1) transitions by means of transient absorption and electron paramagnetic resonance measurements. In terms of the 1(S1S0)-to-1(T1T1) 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(T1T1) quantum yields than C and D, with a maximum value of 162% for A. In terms of the 1(T1T1)-to-5(T1T1) transition, the sizable electronic coupling in A and B is counterproductive, and C and D give rise to higher 5(T1T1)-to-(T1 + T1) quantum yields than A and B, with a maximum value of 85% for D. |
| Databáze: | OpenAIRE |
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