This study deals with the synthesis and characterization of two new di-anchoring dyes for applications in dye-sensitized solar cells. The materials were designed with a branched D(-pi-A)(2) structure containing (i) a rigid alkyl-functionalized carbazole core as the donor part, (ii) one (DYE1) or two (DYE2) thiophene units as the pi-bridge and (iii) a cyano-acrylic moiety as acceptor and anchoring part. Electrochemical impedance spectroscopy indicated that the injected electron lifetime is higher in the case of DYE2, probably due to the length of the pi-spacer that, in combination with the alkyl chain on the carbazole unit, hampers the charge recombination with the electrolyte. Stability tests on TiO2-sensitized films revealed that the di-anchoring remarkably slows down the desorption process, which conversely is evident for classic reference dyes. The highest power conversion efficiency reaches 5.01% in the case of DYE2 with a photovoltage of 0.70 V and a photocurrent of 10.52 mA cm(-2), substantially deriving from a broader absorption with respect to DYE1, as also confirmed by IPCE measurements. These results support the efforts aimed at the structural engineering of D(-pi-A)(2) dyes to design new, more efficient and stable organic sensitizers.
Anchoring stability and photovoltaic properties of new D(-pi-A)(2) dyes for dye-sensitized solar cell applications
Giannuzzi Roberto;GIGLI, Giuseppe
2013-01-01
Abstract
This study deals with the synthesis and characterization of two new di-anchoring dyes for applications in dye-sensitized solar cells. The materials were designed with a branched D(-pi-A)(2) structure containing (i) a rigid alkyl-functionalized carbazole core as the donor part, (ii) one (DYE1) or two (DYE2) thiophene units as the pi-bridge and (iii) a cyano-acrylic moiety as acceptor and anchoring part. Electrochemical impedance spectroscopy indicated that the injected electron lifetime is higher in the case of DYE2, probably due to the length of the pi-spacer that, in combination with the alkyl chain on the carbazole unit, hampers the charge recombination with the electrolyte. Stability tests on TiO2-sensitized films revealed that the di-anchoring remarkably slows down the desorption process, which conversely is evident for classic reference dyes. The highest power conversion efficiency reaches 5.01% in the case of DYE2 with a photovoltage of 0.70 V and a photocurrent of 10.52 mA cm(-2), substantially deriving from a broader absorption with respect to DYE1, as also confirmed by IPCE measurements. These results support the efforts aimed at the structural engineering of D(-pi-A)(2) dyes to design new, more efficient and stable organic sensitizers.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
