Comparative study of 2,7 versus 3,6 disubstituted carbazole as hole transporting materials in solid state DSSC

A comparative study of thermal and electrochemical properties of 2,7 and 3,6 disubstituted carbazole is presented and their performances were compared in solid state Dye Sensitized Solar Cell (DSSC). Although the two compounds possess similar glass transition temperature of 100°C, their electrochemical behaviors are quite different. HOMO energy levels have been evaluated at -4.7 eV and -5.1 eV respectively for 2,7 and 3,6 disubstituted carbazole derivatives. Incorporated as hole transporting materials in solid state DSSC, the 2,7 carbazole exhibits an efficiency conversion of 0.18 % while the 3,6 carbazole gives 0.34 % of efficiency conversion due to a better pore filling in the mesoporous TiO₂.