Synthesis and characterization of Y-shape electron donor-acceptor type organic dyes for dye-sensitized solar cells

Three Y-shape organic dyes, (Z)-3-(5-(3,5-bis(4-(9H-carbazol-9-yl)styryl)-4-methoxyphenyl)thiophen-2-yl)-2-cyanoacrylic acid (OD-1), (Z)-3-(5'-(3,5-bis(4-(9H-carbazol-9-yl)styryl)-4-methoxyphenyl)-2,2'-bithiophen-5-yl)-2-cyanoacrylic acid (OD-2) and (Z)-3-(5'-(3,5-bis(4-(9H-carbazol-9-yl)styryl)-4-methoxyphenyl)-3,4'-4 ''-trithiophenyl-5-yl)-2-cyanoaaylic acid (OD-3) were synthesized and used as sensitizers in nanocrystalline dye-sensitized solar cells (DSSCs). The introduction of the bis(carbazolyl-styryl) units as an electron donor group and oligothiophene units as a both electron donors and pi-spacers increased the conjugation length of the sensitizers and thus improved their molar absorption coefficient and light harvesting efficiency. DSSCs with the configuration of SnO2:F/TiO2/organic dye/liquid electrolyte/Pt devices were fabricated using these OD-1, OD-2 and OD-3 as a sensitizers. Among the devices, the DSSC composed of OD-3 exhibited highest power conversion efficiency of 3.03% under AM1.5G (100 mW cm(-2)). (C) 2013 Elsevier B.V. All rights reserved.