Enhanced performance of solution-processed solar cells based on porphyrin small molecules with a diketopyrrolopyrrole acceptor unit and a pyridine additive

A conjugated donor-acceptor porphyrin small molecule was designed and synthesized with diketopyrrolopyrrole as the acceptor unit. The new porphyrin-based small molecule exhibits broad and intense absorption in the visible and near IR regions, and the hole mobility and the power conversion efficiency of the bulk heterojunction devices based on the porphyrin : [ 6,6]-phenyl-C-61-butyric acid methyl ester (1 : 1, w/w) are increased up to 4.6 x 10(-5) cm(2) V-1 s(-1) and 3.71%, respectively, which are further enhanced to 1.6 x 10(-4) cm(2) V-1 s(-1) and 4.78%, respectively, upon the introduction of 3.0 vol% of pyridine additive. Further studies show that the performance of the solar cells based on other zinc porphyrins could also be improved by the pyridine additive.