Low-cost dyes based on methylthiophene for high-performance dye-sensitized solar cells

Three donor-acceptor, pi-conjugated (D-pi-A) dyes containing methylthiophene or vinylene methylthiophene as pi-conjugated spacer were utilised in dye-sensitized nanocrystalline TiO2 solar cells. The relationship between the structure of the dyes and their photophysical, electrochemical and photovoltaic properties was investigated systematically. The vinyl unit, introduced as the pi-conjugated spacer, leads to unfavorable back-electron transfer and decrease of the open-circuit voltage. A dye-sensitized solar cell based on 2-cyano-3-(5-(4-(diphenylamino)phenyl)-4-methylthiophenyl-2-yl) acrylic acid displayed the most efficient solar-to-electricity conversion efficiency of the dyes with a maximum eta value of 8.27% (V-oc = 0.72 V, J(sc) = 15.76 mA cm(-2), FF = 0.73) under simulated AM 1.5 G solar irradiation (100 mW cm(-2)). (C) 2010 Elsevier Ltd. All rights reserved.