We analyze the linear absorption spectrum of regioregular poly (3-hexylthiophene) films
spun from a variety of solvents to probe directly the film microstructure and how it depends
on processing conditions. We estimate the exciton bandwidth and the percentage of the film
composed of aggregates quantitatively using a weakly interacting H-aggregate model. This
provides a description of the degree and quality of crystallites within the film and is in turn
correlated with thin-film field-effect transistor characteristics.In thin films, regioregular poly (3 …