Poly(3‐hexylthiophene) aggregation at solvent–solvent interfaces

Abstract

The aggregation behavior of P3HT is investigated at the interface of orthogonal solvents for P3HT. The changeable characteristics of P3HT aggregate dispersions, for example, extent of aggregation and intrachain order, are studied by varying (1) the interfacial area, (2) the poor solvent used to induce aggregationdichloromethane (DCM), hexane (HEX), and acetonitrile (AcN)and (3) the relative composition of the good solvent, chloroform (CF), and poor solvents. The results are compared to those observed using rapid injection of the solvent. Miscibility gap values (Dd) provide a reasonable justification of the assembly behavior of P3HT in the solvent mixtures in terms of the kinetics of polymer aggregation and the kinetics of solvent mixing at the interface. Atomic force microscopy (AFM) is used to analyze the morphology of films processed from dispersions with disparate characteristics, but having the same solvent composition, for example, 70:30 CF:HEX or 60:40 CF:DCM. Based on the disparity of the kinetics and miscibility gap values, the prevalence of specific structural motifs in the films, for example, spheroids (globules) and fibers, is effectively rationalized in terms of the structural attributes of the aggregates in the liquid phase rather than the evaporation rate (boiling point) differences of the solvents in the mixture.

Effect of Alcohol Polarity on the Aggregation and Film-Forming Behaviors of Poly(3-hexylthiophene)

“…In a solvent mixture containing a solvent additive, the miscibility of the solvent additive with the main solvent in the solution state strongly affects polymer aggregation. , Because the solvent additive is present at a concentration of only a few mass % in the polymer solution, the proximity of the additive solvent molecules to the polymer chains determines the degree of polymer aggregation in the solution state . In the solution state, the alcohol solvent added to the main solvent mixes favorably if the solvents exhibit strong intermolecular interactions. , In the present study, the alcohol solvent additives are polar molecules, which exhibit dipole–dipole interactions with the main solvent, CF. The polarity of the solvent can be quantified and compared using polarity parameters .…”

“…The intermixing between a main solvent and a solvent additive plays a substantial role in polymer aggregation in the solution state. ,, We systematically chose alcohol solvent additives with various alkyl lengths ranging from methyl to butyl to study the effect of the properties of the solvent additive on polymer conformation. Alcohol solvents are poor solvents of conjugated polymers such as the P3HT used in the present study; hence, they induce strong aggregation of P3HT when P3HT molecules are in close proximity to the alcohol solvent molecules.…”

“…40 In the solution state, the alcohol solvent added to the main solvent mixes favorably if the solvents exhibit strong intermolecular interactions. 37,39 In the present study, the alcohol solvent additives are polar molecules, which exhibit dipole−dipole interactions with the main solvent, CF. The polarity of the solvent can be quantified and compared using polarity parameters.…”

Effects of Thin Film Morphology of Polymer Hole Transfer Material on Photovoltaic Performance of Perovskite Solar Cells

“…P3HT nanowires were formed by adding KZ and UZ-P3HT materials obtained from P-HPLC to 10 mg/ml chlorobenzene: hexane (ratio: 6:4) solution and then keeping those solutions at room temperature for 1 h without stirring. The resulting solutions were filmed with the same coating and drying process as P3HT mixtures [26].…”