Novel dithieno[3,2-b:2′,3′-d]pyrrole-based organic dyes with high molar extinction coefficient for dye-sensitized solar cells

Three new metal-free organic dyes FD1-3 with a planar dithieno[3,2-b:2',3'-d]pyrrole unit as linker were synthesized and used for dye-sensitized solar cells with high molar extinction coefficients. In this work, dithieno[3,2-b: 2',3'-d]pyrrole was employed as p-conjugated bridge to construct A-pi-D-pi-A organic dyes, where 9,9-dihexyl-9H-fluorene was used as a donor, and cyanoacrylic acid as an electron acceptor. For a typical device, a solar energy conversion efficiency (eta) of 6.36% based on FD2 was achieved under simulated AM 1.5 solar irradiation (100 mW cm(-2)) with a short-circuit photocurrent density (J(sc)) of 13.76 mA cm(-2), an open-circuit voltage (V-oc) of 669 mV, a fill factor (ff) of 0.691. The results suggest that the organic dye with a functionalized dithienopyrrole unit is a promising candidate for DSSCs due to its high molar extinction coefficients. (C) 2013 Elsevier B.V. All rights reserved.