LAUSR

Abstract We have defined average photon energy (Eave) to describe energy changes in UV–vis absorbance spectra during the aggregation of conjugated polymer solutions quantitatively. During the aggregation process of P3HS (poly(3-hexylselenophene)), Eave always decreases and maximum aggregation absorbance (ABSmagg) always increases, and relationships between (Eave and ABSmagg) and time are single exponential models. The relationship between ABSmagg and Eave of P3HS is a single Gaussian model, so Eave can be used to predict the amount of aggregate. Eave and ABSmagg of P3HT (Poly(3-hexylthiophene)) follow similar rules of P3HS. This work describes energy changes and predicts the amount of aggregate in UV–vis spectra during the aggregation process.