Dithienothiophene (DTT)-Based Dyes for Dye-Sensitized Solar Cells: Synthesis of 2,6-Dibromo-DTT

Abstract

A one-pot synthesis of 2,6-dibromodithieno [3,2-b;2', 3'-d]thiophene (dibromo-DTT, 4) was developed. A key step was bromo-decarboxylation of DTT-2,6-dicarboxylic acid, obtained by saponification of the diester 1. The donor-acceptor dye DAHTDTT (13), based on a central 2,6-bis[2'-(3'-hexylthienyl)]dithieno[3,2-b;2',3'-d]thiophene core (9), was prepared and incorporated in a dye-sensitized solar cell (DSC), which exhibited an energy conversion efficiency of 7.3% with V(oc) of 697 mV, J(sc) or 14.4 mA/cm(2), and ff of 0.73 at 1 sun.