Investigation into aggregation types in a benzodithiophene-isoindigo copolymer

Eninges Asmare; Fekadu Gashaw Hone; Wendimagegn Mammo; Tjaart P J Krüger; Newayemedhin A Tegegne

doi:10.1063/5.0151318

Investigation into aggregation types in a benzodithiophene-isoindigo copolymer

J Chem Phys. 2023 Jul 21;159(3):034901. doi: 10.1063/5.0151318.

Authors

Eninges Asmare¹, Fekadu Gashaw Hone¹, Wendimagegn Mammo², Tjaart P J Krüger^{3

4}, Newayemedhin A Tegegne¹

Affiliations

¹ Department of Physics, Addis Ababa University, Addis Ababa 1176, Ethiopia.
² Department of Chemistry, Addis Ababa University, Addis Ababa 33658, Ethiopia.
³ University of Pretoria, Department of Physics, Pretoria, South Africa.
⁴ National Institute for Theoretical and Computational Sciences, (NITheCS), South Africa.

PMID: 37458353
DOI: 10.1063/5.0151318

Abstract

The type of aggregation in conjugated polymers determines their use in electronic devices. H-type aggregates are most suitable for solar cell applications, while J-type aggregates are recommended for light-emitting diodes. In this work, we used three methods to determine the type of aggregates in a benzodithiophene-isoindigo-based (PBDTI-DT) copolymer, namely, Huang-Rhys factor evolution with temperature, Franck-Condon analysis, and relative quantum yield (QY) calculation. All three methods indicate that both aggregation types are present, and the QY calculation clearly indicates that H-aggregates are more dominant. Time-dependent density functional theory was used to identify the two absorption bands of PBDTI-DT as local π - π* and intramolecular charge-transfer transitions.