Effect of pi-spacers on the photovoltaic properties of D-pi-A based organic dyes
Three new triphenylamine based D-pi-pi-A (TPC, TSC and TOC) dyes with different pi-spacers have been synthesized and analysed their significance on the photophysical properties and photovoltaic applications. The synthesized dyes were characterized by NMR, mass, melting point, absorbance and electrochemical measurements. In these dyes, triphenylamine moiety was utilized as electron donor and cyanoacetic acid acts as an electron acceptor. By keeping phenyl acetonitrile as one pi-spacer and another pi-spacer is varied by benzeneifuran/thiophene group and their consequences on the photophysical, electrochemical and photovoltaic properties were analysed. Photovoltaic parameter such as short circuit current density (J(SC)) and open circuit voltage (V-OC) is found to be significantly varied by changing the pi-spacer. The maximum absorption was observed for TSC with thiophene linker which results in high J(SC) value than TPC and TOC. However, a high V-OC of TPC results in better photovoltaic performance of 3.52% among other dyes. The outcome from the photophysical and photovoltaic measurements implies that the phenyl and thiophene spacer yields higher power conversion efficiency when compared to the furan bridged dye. The observed results will provide basic information for future designing of sensitizers with different pi-spacers for photovoltaic applications. (C) 2014 Elsevier B.V. All rights reserved.