Vibronic coherences in light harvesting nanotubes: unravelling the role of dark states

Year: 2022

Authors: Doria S.; Di Donato M.; Borrelli R.; Gelin M.F.; Caram J.; Pagliai M.; Foggi P.; Lapini A.

Autors Affiliation: ICCOM-CNR, via Madonna del Piano 10, (FI), Sesto Fiorentino, I-50019, Italy; LENS (European Laboratory for Non-Linear Spectroscopy), Via N. Carrara 1, FI, Sesto Fiorentino, 50019, Italy; DISAFA, University of Torino, Largo Paolo Braccini 2, Grugliasco Torino Italy; School of Sciences, Hangzhou Dianzi University, Hangzhou, 310018, China; Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095, United States; Dipartimento di Chimica “Ugo Schiff”, Universita degli Studi di Firenze, via della Lastruccia 3, Sesto Fiorentino, Italy; Department of Chemistry, University of Perugia, Centro di Eccellenza sui Materiali Innovativi Nanostrutturati (CEMIN), Biology and Biotechnology, via Elce di Sotto 8, Perugia, 06123, Italy; INO-CNR, Largo Fermi 6, Firenze , Italy; Dipartimento di Scienze Chimiche della Vita e della Sostenibilita Ambientale, Parco area delle Scienze, universita degli studi di Parma, Italy

Abstract: Self-assembled ordered structures, such as H- or J-type molecular aggregates of organic chromophores, are extremely interesting materials for different optoelectronic applications. In this work we present a novel characterization of light harvesting nanotubes formed by the self-assembly of amphiphilic cyanine dyes in water, through a combined ultrafast spectroscopic and theoretical approach. Under the condition of low inhomogeneous disorder at low temperature, broadband transient absorption spectroscopy revealed the presence of an unusual ultrafast behavior of the aggregate, manifested through intense and peculiar oscillations of the kinetic traces, lasting tens of picoseconds. Theoretical simulations were performed by adapting a model which grasps vibronically coherent effects in the double wall nanotube system experiencing inter-wall energy transfer. Good agreement between model predictions and experimental observations was obtained under the assumption of coupling between bright and dark electronic states. The model clarified the vibronic origin of the observed oscillations, evidencing new important pieces of information about transport mechanisms and excitonic interactions in these complex molecular systems.

Journal/Review: JOURNAL OF MATERIALS CHEMISTRY C

Volume: 10      Pages from: 7216  to:

More Information: The authors thank the European Unions Horizon 2020 research and innovation program under grant agreement no. 871124 Laserlab-Europe. R. B acknowledges funding from the European Unions Horizon 2020 Research and Innovation Program under Grant Agreement No. 826013. M. F. G. acknowledges support from the Hangzhou Dianzi University through startup funding.
KeyWords: Absorption spectroscopy; Aggregates; Chromophores; Energy transfer; Excitons; Temperature
DOI: 10.1039/d2tc00203e

Citations: 9
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