Recombination in dye-sensitized solar cells with direct injection is cast as internal conversion in the dye-Ti(OH)(2) complex. For catechol-thiophene dyes with 1, 2, or 3 thiophene units, the complex reproduces the previously observed dye-to-semiconductor bands. We compare the decomposition of the internal conversion rate by vibrational mode and predict a trend in recombination with the extension of conjugation, which offers an explanation for the trend in DSSC efficiency. We employ a simple model for the vibrational factors and show that they are only important in the presence of vibrational modes with (h) over bar omega >= kT and strong electronic factors, as is the case here. (C) 2011 Elsevier B. V. All rights reserved.