Effects of solution concentration on properties of P3HT films
Keane, Daniel P
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Past experiments have studied Poly(3-hexylthiophene-2,5-diyl) (P3HT) by examining the roles of parameters including molecular weight, aggregation methods, and dispersion method on device performance. However, the role of the P3HT solution concentration on the polymer’s properties are not fully understood. This research examined the role of polymer solution concentration on the properties of UV-treated P3HT. P3HT of two different molecular weights was examined, and three different concentrations each were examined for each weight. To characterize a given weight-concentration combination, electrical capabilities of the films were measured on FETs, UV-vis measurements were taken of solution and films, and films were examined under Atomic Force Microscopy (AFM). The results suggest that the long-range order of P3HT films is closely related to the solution concentration. For films created from higher solution concentrations, more fibers in films of P3HT are aligned in the same direction and a larger fraction of polymer in the solution is aggregated. Of the three solution concentrations tested, the middle concentrations performed the best electrically, suggesting that solubility factors, chain count, and viscosity strongly affect the resulting film’s properties.