Dynamics of Preaggregation and Film Formation of Donor–Acceptor π-Conjugated Polymers

Abstract

It is important to understand the film formation mechanism of π-conjugated polymers to realize their high-performance electronic devices. In this study, the dynamics of the preaggregate, which affects the conformation and alignment of a typical donor−acceptor (D-A) π-conjugated polymer during film formation, was investigated by two approaches based on a smallangle X-ray scattering (SAXS) method. SAXS analysis of a highly concentrated solution, assuming the state before becoming the solid-state thin film, provided insight into the aggregation phenomena of the D-A π-conjugated polymer during the film formation process. In solution, the small rod-like structure of the polymer seems to form a large preaggregate, the shape of which almost coincided with that of the aggregate in the solid-state thin film. Besides, in situ grading incident SAXS (in situ GISAXS) analysis in the actual film formation process from the solution state revealed a microstructural change of the aggregate over time.

Increasing H-Aggregates via Sequential Aggregation to Enhance the Hole Mobility of Printed Conjugated Polymer Films

“…This is consistent with the weaker interactions of the PDPP-TVT side chains with BrN than those with CF, which leads to the lower solubility of PDPP-TVT in pure BrN. Notably, the size of PDPP-TVT aggregates in the initial solution was substantially smaller than that in the solid film, implying that these aggregates grow up during the film formation process …”

“…Notably, the size of PDPP-TVT aggregates in the initial solution was substantially smaller than that in the solid film, implying that these aggregates grow up during the film formation process. 47 Aggregation Dynamics during Film Formation. We used time-resolved optical diagnostics to track the PDPP-TVT aggregation dynamics during film formation process to comprehend the impact of BrN.…”

Fast-Coating Process Based on Elongated Rodlike Preaggregate for Highly Oriented Thin Film of Donor–Acceptor π-Conjugated Polymer

“…The isolated PDPP-DTT chains in CF and TCE seem to form the folded state in the solution and to become a further folded state at high concentration as reported previously. 29 The size and shape of the preaggregate strongly depended on the concentration and solvents. The gyration of radius R g2 of preaggregate increased depending on concentration except for the case of CF, which indicates the increase of the number of the polymers in the preaggregate.…”

“…Solution Preparation and SAXS Analysis. 29 PDPP-DTT of M w = 56000 g/mol and PDI = 2.7 was purchased from Merck. The powder of PDPP-DTT was dissolved in a solvent by heating with a hot plate at 80 °C for 10 min.…”

Solvation-Shell-Induced Entropic Repulsion and Insights into Solvent Quality of Crystalline Conjugated Polymer Solutions

“…Understanding the mechanistic features by which different types of solvent media dictate the solubility and aggregation (or crystallinity) properties of crystalline conjugated polymers, such as the widely studied polythiophene series as of 2022, − can greatly facilitate the advance of contemporary science and technology on organic photovoltaic cells (OPVs) and organic field-effect transistors (OFETs). − Often, solvent media that offer tolerable solubility in these applications are classified into two categories: better solvents that yield good nominal solubility but poor crystallinity and poorer solvents that help promote the crystallinity at the cost of polymer solubility. , The interesting compromise between the two types of solvent media in light of their overall impact on the performance of the devices so fabricated has since motivated a continued search for optimal solvent media in current applications with crystalline conjugated polymers. − ,− From a scientific perspective, the origins and mechanistic features of solvent quality remain elusive in general. Although there have been many experimental studies − ,,− that offer illuminating insights into these issues, no definite physical picture has yet been reached that can clearly explain the thermodynamics and kinetics dictating the initial stage of solvation and association when solvent quality changes, which would eventually lead to the bulk aggregation state measurable by conventional experimental schemes. Computer simulations can, in principle, be invaluable in this respect.…”