Efficient organic dyes based on perpendicular 6,12-diphenyl substituted indolo[3,2-b]carbazole donor.

Three novel indolo[3,2-b]carbazole-based dyes have been designed and synthesized using a 6,12-diphenyl substituted indolo[3,2-b]carbazole core as a π-conjugated donor, a thiophene cyanoacrylic acid moiety as electron acceptor and anchoring group, together with triphenylamine, 3,4,5-trimethoxybenzene and bromine as a second donor group. The photophysical and electrochemical properties of the dyes have been investigated by UV spectroscopy and cyclic voltammetry (CV). Our study indicates that the second donor plays the important role of improving dye aggregation as well as tuning the photoelectronic properties. These indolo[3,2-b]carbazole based dyes show good performances with high Voc of 0.75 V, FF of 0.72, and a moderate PCE of 3.11% under AM 1.5 irradiation.