Journal article

Publication year: 2022

Pages: 3569-3581

Journal: Journal of Physical Chemistry C

Volume number: 126

Issue number: 7

ISSN: 1932-7447

eISSN: 1932-7455

Open access status: Hybrid

DOI Link: https://doi.org/10.1021/acs.jpcc.1c10570

Publisher: American Chemical Society

Abstract: 
The search for synthetic materials that mimic natural photosynthesis by converting solar energy into other more useful forms of energy is an ever-growing research endeavor. Graphene-based materials, with their exceptional electronic and optical properties, are exemplary candidates for high-efficiency solar energy harvesting devices. High photoactivity can be conveniently achieved by functionalizing graphene with small molecule organic semiconductors whose band-gaps can be tuned by structural modification, leading to interactions between the pi-conjugated electronic systems in both the semiconductor and graphene. Here we investigate the ultrafast transient optical properties of a cross-linked graphene-dye (diphenyl-dithiophenediketopyrrolopyrrole) nanohybrid material, in which oligomers of the organic semiconductor dye are covalently bound to a random network of few-layer graphene flakes, and compare the results to those obtained for the reference dye monomer. Using a combination of ultrafast transient absorption and two-dimensional electronic spectroscopy, we provide substantial evidence for photoinduced charge transfer that occurs within 18 ps in the nanohybrid system. Notably, subpicosecond photoinduced torsional relaxation observed in the constituent dye monomer is absent in the cross-linked nanohybrid system. Through density functional theory calculations, we compare the competing effects of covalent bonding, increasing conjugation length, and the presence of multiple graphene flakes. We find evidence that the observed ultrafast charge transfer process occurs through a superexchange mechanism in which the oligomeric dye bridge provides virtual states enabling charge transfer between graphene-dye covalent bond sites.

Harvard Citation style: Ross, A., Osella, S., Policht, V., Zheng, M., Maggini, M., Marangi, F., et al. (2022) Deciphering Photoinduced Charge Transfer Dynamics in a Cross-Linked Graphene-Dye Nanohybrid, Journal of Physical Chemistry C, 126(7), pp. 3569-3581. https://doi.org/10.1021/acs.jpcc.1c10570

APA Citation style: Ross, A., Osella, S., Policht, V., Zheng, M., Maggini, M., Marangi, F., Cerullo, G., Gatti, T., & Scotognella, F. (2022). Deciphering Photoinduced Charge Transfer Dynamics in a Cross-Linked Graphene-Dye Nanohybrid. Journal of Physical Chemistry C. 126(7), 3569-3581. https://doi.org/10.1021/acs.jpcc.1c10570