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Multitype Electronic Interactions in Precursor Solutions of Molecular Doped P3HT Polymer.
- Source :
-
The journal of physical chemistry. B [J Phys Chem B] 2024 Apr 04; Vol. 128 (13), pp. 3249-3257. Date of Electronic Publication: 2024 Mar 20. - Publication Year :
- 2024
-
Abstract
- Spin-casting of molecularly doped polymer solution mixtures is one of the commonly used methods to obtain conductive organic semiconductor films. In spin-casted films, electronic interaction between the dopant and polymer is one of the crucial factors that dictates the doping efficiency. Here, we investigate excitonic couplings using ultrafast two-dimensional electronic spectroscopy to examine the different types of electronic interactions in ion pairs of the prototype F <subscript>4</subscript> TCNQ-doped P3HT polymer system in a precursor solution mixture for spin-casting. Off-diagonal peaks in the 2D spectra clearly establish the excitonic coupling between P3HT <superscript>+</superscript> and F <subscript>4</subscript> TCNQ <superscript>-</superscript> ions in solution. The observed excitonic coupling is the direct manifestation of a Coulombic interaction between the ion pair. The excited-state lifetime of F <subscript>4</subscript> TCNQ <superscript>-</superscript> in ion pairs shows biexponential decay at 30 and 200 fs, which hints toward the presence of a heterogeneous population with different interaction strengths. To examine the nature of these different types of interactions in solution mixtures, we study the system using molecular dynamics simulations on a fully solvated model employing the generalized Amber force field. We retrieve three dominant interaction modes of F <subscript>4</subscript> TCNQ anions with P3HT: side chain, π-stack, and slipped stack. To quantify these interactions, we complement our studies with electronic structure calculations, which reveal the excitonic coupling strengths of ∼ 75 cm <superscript>-1</superscript> for side chain, ∼ 150 cm <superscript>-1</superscript> for π-π-stack, and ∼69 cm <superscript>-1</superscript> for slipped stack. These various interaction modes provide information about the key geometries of the seed structures in precursor solution mixtures, which may determine the final structures in spin-casted films. The insights gained from our study may guide new strategies to control and ultimately tune Coulomb interactions in polymer-dopant solutions.
Details
- Language :
- English
- ISSN :
- 1520-5207
- Volume :
- 128
- Issue :
- 13
- Database :
- MEDLINE
- Journal :
- The journal of physical chemistry. B
- Publication Type :
- Academic Journal
- Accession number :
- 38507573
- Full Text :
- https://doi.org/10.1021/acs.jpcb.4c00584