Mimicking Conjugated Polymer Thin-Film Photophysics with a Well-Defined Triblock Copolymer in Solution

• Published in: The journal of physical chemistry. B 2013-04, Vol.117 (16), p.4170-4176
• Main Authors: Brazard, Johanna, Ono, Robert J, Bielawski, Christopher W, Barbara, Paul F, Vanden Bout, David A
• Format: Article
• Language: English
• Subjects: Applied sciences; Block copolymers; Collapse; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Electrical, magnetic and optical properties; Electronic spectra; Electronics; Exact sciences and technology; Fluorescence; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Mathematical models; Organic polymers; Physicochemistry of polymers; Properties and characterization; solar (photovoltaic), phonons, energy storage (including batteries and capacitors), defects, charge transport, materials and chemistry by design, synthesis (novel materials), synthesis (self-assembly); SOLAR ENERGY; Solvents; Thin films
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/jp3001256

Conjugated polymers (CPs) are promising materials for use in electronic applications, such as low-cost, easily processed organic photovoltaic (OPV) devices. Improving OPV efficiencies is hindered by a lack of a fundamental understanding of the photophysics in CP-based thin films that is complicated by their heterogeneous nanoscale morphologies. Here, we report on a poly(3-hexylthiophene)-block-poly(tert-butyl acrylate)-block-poly(3-hexylthiophene) rod–coil–rod triblock copolymer. In good solvents, this polymer resembles solutions of P3HT; however, upon the addition of a poor solvent, the two P3HT chains within the triblock copolymer collapse, affording a material with electronic spectra identical to those of a thin film of P3HT. Using this new system as a model for thin films of P3HT, we can attribute the low fluorescence quantum yield of films to the presence of a charge-transfer state, providing fundamental insights into the condensed phase photophysics that will help to guide the development of the next generation of materials for OPVs.