Solid-state absorption, luminescence, and singlet fission of furanyl-substituted diketopyrrolopyrroles with different pi-stacking arrangements

0579769 - ÚMCH 2025 RIV US eng J - Journal Article
Kratochvíl, M. - Thottappali, Muhammed Arshad - Luňák, S. Jr. - Pauk, K. - Rais, David - Marková, A. - Pfleger, Jiří - Imramovský, A. - Vala, M.
Solid-state absorption, luminescence, and singlet fission of furanyl-substituted diketopyrrolopyrroles with different pi-stacking arrangements.
ChemPhotoChem. Roč. 7, č. 12 (2023), č. článku e202300201. ISSN 2367-0932. E-ISSN 2367-0932
R&D Projects: GA ČR(CZ) GA22-02005S
Institutional support: RVO:61389013
Keywords : singlet fission * diketopyrrolopyrrole * solid state photophysics
OECD category: Materials engineering
Impact factor: 3.7, year: 2022
Method of publishing: Open access
https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/cptc.202300201

Small modifications of the diketopyrrolopyrrole (DPP) molecular structure induced remarkable changes in its spectral and photophysical behavior. Using furan (F) heterosubstitution instead of thiophene (T) substituent resulted in a small blue shift and decreased Huang-Rhys factor of the absorption spectra in solution, irrespectively to N,N'-alkyls. Branching of alkyl side chains by formal 2-ethylation of n-hexyl substituent (C6 to EH) switched the slipped-stack arrangement, irrespectively on the heteroatoms. Consequent changes in steady-state absorption spectra of thin films were interpreted using time dependent density functional theory calculations, carried out on model dimers. Solid-state luminescence is weak and partially dependent on an excitation wavelength. Singlet fission was observed by femtosecond transient absorption spectroscopy, with considerably different yields for variously π-stacked FDPP-EH (30 %) and FDPP-C6 (160 %). The shape of triplet-triplet absorption spectra was also influenced by various π-stacking. The results are discussed in terms of different mixing of both Frenkel and charge transfer states in model dimers and different excitonic and electronic coupling in both types of π-stacks, visualized by natural transition orbitals.
Permanent Link: https://hdl.handle.net/11104/0348775