Multitype Electronic Interactions in Precursor Solutions of Molecular Doped P3HT Polymer

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 F4TCNQ-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+ and F4TCNQ- ions in solution. The observed excitonic coupling is the direct manifestation of a Coulombic interaction between the ion pair. The excited-state lifetime of F4TCNQ- 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 F4TCNQ 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-1 for side chain, ∼ 150 cm-1 for π-π-stack, and ∼69 cm-1 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.

Medienart:

E-Artikel

Erscheinungsjahr:

2024

Erschienen:

2024

Enthalten in:

Zur Gesamtaufnahme - volume:128

Enthalten in:

The journal of physical chemistry. B - 128(2024), 13 vom: 04. Apr., Seite 3249-3257

Sprache:

Englisch

Beteiligte Personen:

Tiwari, Vandana [VerfasserIn]
Li, Xin [VerfasserIn]
Li, Zheng [VerfasserIn]
Jacobs, Ian E [VerfasserIn]
Duan, Hong-Guang [VerfasserIn]
Sirringhaus, Henning [VerfasserIn]
Miller, R J Dwayne [VerfasserIn]
Jha, Ajay [VerfasserIn]

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Date Revised 04.04.2024

published: Print-Electronic

Citation Status PubMed-not-MEDLINE

doi:

10.1021/acs.jpcb.4c00584

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM369971582