Femtosecond Dynamics of Photoexcited C 60 Films

Causa, Martina; Ramirez, Ivan; Martinez Hardigree, Josue F.; Riede, Moritz; Banerji, Natalie (2018). Femtosecond Dynamics of Photoexcited C 60 Films. The journal of physical chemistry letters, 9(8), pp. 1885-1892. American Chemical Society 10.1021/acs.jpclett.8b00520

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The well known organic semiconductor C60 is attracting renewed attention due to its centimeter-long electron diffusion length and high performance of solar cells containing 95% fullerene, yet its photophysical properties remain poorly understood. We elucidate the dynamics of Frenkel and intermolecular (inter-C60) charge-transfer (CT) excitons in neat and diluted C60 films from high-quality femtosecond transient absorption (TA) measurements performed at low fluences and free from oxygen or pump-induced photodimerization. We find from preferential excitation of either species that the CT excitons give rise to a strong electro-absorption (EA) signal but are extremely short-lived. The Frenkel exciton relaxation and triplet yield strongly depend on the C60 aggregation. Finally, TA measurements on full devices with applied electric field allow us to optically monitor the dissociation of CT excitons into free charges for the first time and to demonstrate the influence of cluster size on the spectral signature of the C60 anion.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Departement of Chemistry and Biochemistry

UniBE Contributor:

Causa, Martina and Banerji, Natalie

Subjects:

500 Science > 570 Life sciences; biology
500 Science > 540 Chemistry
500 Science > 530 Physics

ISSN:

1948-7185

Publisher:

American Chemical Society

Language:

English

Submitter:

Gareth John Moore

Date Deposited:

07 Dec 2018 13:22

Last Modified:

07 Dec 2018 13:22

Publisher DOI:

10.1021/acs.jpclett.8b00520

BORIS DOI:

10.7892/boris.121529

URI:

https://boris.unibe.ch/id/eprint/121529

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