Photophysics, electronic structure and solar cell performance of a donor-acceptor poly(N-dodecyl-2,7-carbazole-alt-benzothiadiazole) copolymer

Aimilios Koutsoubelitis (1) , Kostas Seintis (1) , Dimitrios Tsikritzis (1) , Jules Oriou (2) , Cyril Brochon (2) , Eric Cloutet (2) , Georges Hadziioannou (2) , Maria Vasilopoulou , Stella Kennou (3) , Mihalis Fakis (1) , Leonidas Palilis (1)

1 University of Patras
2 Team 4 LCPO : Polymer Materials for Electronic, Energy, Information and Communication Technologies
3 Department of Chemical Engineering

In this contribution, we investigate the optoelectronic properties of a donor-acceptor poly(N-Dodecyl-2,7-carbazole-alt-benzothiadiazole (CBZ-BT) copolymer in solutions and thin films, by a combination of complementary optical and electronic spectroscopy techniques including stationary absorption and fluorescence, femtosecond time-resolved and ultraviolet/x-ray photoelectron spectroscopy. Absorption spectroscopy revealed two bands at 322/338 and 445/475 nm for CBZ-BT in solutions/films attributed to the carbazole and benzothiadiazole groups respectively. Photoexcitation either to the absorption band of the carbazole or benzothiadiazole group led to a broad and structureless fluorescence spectrum due to large torsional disorder in the excited state, originating from intramolecular energy transfer between carbazole and benzothiadiazole. Time resolved spectroscopy in solutions reveals a transient red-shift of the emission spectrum within less than 5 ps due to exciton migration and/or conformational relaxation of the polymer backbone. In films, this relaxation is faster accompanied by a quenching of the exciton lifetime.

Mots clés: Photophysic properties; Conjugated Polymers

Domaines: Polymères; Science des matériaux [cond-mat.mtrl-sci]; Chimie-Physique [physics.chem-ph]

Aimilios Koutsoubelitis, Kostas Seintis, Dimitrios Tsikritzis, Jules Oriou, Cyril Brochon, et al.. Photophysics, electronic structure and solar cell performance of a donor-acceptor poly(N-dodecyl-2,7-carbazole-alt-benzothiadiazole) copolymer. Organic Electronics, 2018, 59, pp.202-212. ⟨10.1016/j.orgel.2018.04.047⟩. ⟨hal-01783553⟩