Absorption spectra of natural pigments as sensitizers in solar cells by TD-DFT and MRPT2: protonated cyanidin.

The study of molecular species suitable as sensitizers in solar cells involves the understanding of their visible absorption spectrum. In this article we present a detailed theoretical study of the visible band which has been observed for cyanidin in acid solution. We performed accurate DFT and MRPT2 calculations on the protonated cyanidin in vacuo and in solution, where we have also computed the lineshape profile by including the effects of nuclear degrees of freedom in the harmonic approximation.