Carbazole based A-π- D-π-A dyes with double electron acceptor for dye-sensitized solar cell

Three novel carbazole-based A-pi-D-pi-A-featured dyes (CSG1-CSG3) have been designed, synthesized for applications in dye-sensitized solar cells and fully characterized with NMR, MS, IR, UV-vis and electrochemical measurements. These dyes share the same donor (N-hexylcarbazole) and acceptor/anchoring group (cyanoacrylic acid), but differs in conjugated linkers incorporated, such as benzene, furan or thiophene, to configure the novel A-pi-D-pi-A framework for effective electron flow. The power conversion efficiencies were observed to be sensitive to the p-bridging linker moiety. The photovoltaic experiments showed that dye with a benzene linker exhibited a higher open-circuit voltage (0.699 V) compared to thiophene and furan linker. Among all dyes, CSG2 containing a thiophene linker exhibited the maximum overall conversion efficiency of 3.8% (J(SC) = 8.90 mA cm (2), V-OC = 584 mV, FF = 0.74) under standard global AM 1.5 G solar condition. Under similar fabrication conditions, champion dye N719 exhibited the maximum overall conversion efficiency of 6.4% (J(SC) = 14.74 mA cm (2), V-OC = 606 mV, FF = 0.716). (C) 2013 Elsevier B.V. All rights reserved.