Indolo[2,3-b]carbazole Synthesized from a Double-Intramolecular Buchwald–Hartwig Reaction: Its Application for a Dianchor DSSC Organic Dye

A new synthetic strategy for indolo[2,3-b]carbazole via a double-intramolecular Buchwald–Hartwig reaction has been established. The N-alkylated indolo[2,3-b]carbazole then was adopted as the geometry-fixed core for the synthesis of a new molecule (ICZDTA) bearing two bithiophene π-bridged 2-cyanoacrylic acid groups as the bidentate anchor. The bidentate anchoring together with efficient HOMO (indolo[2,3-b]carbazole) → LUMO (TiO2 nanocluster) electron transfer leads to the successful development of ICZDTA-based DSSC with a power conversion efficiency of 6.02%.