Positional isomers of pyridine linked triphenylamine-based donor-acceptor organic dyes for efficient dye-sensitized solar cells

Abstract

Two donor-acceptor (D-A) metal free dyes 3-{4-[Bis-(4-pyridin-2-ylethynyl-phenyl)-amino]-phenyl}-2-cyano-acrylic acid (D1) and 3-{4-[Bis-(4-pyridin-3-ylethynyl-phenyl)-amino]-phenyl}-2-cyano-acrylic acid (D2) have been designed, synthesized and used as sensitizers for the dye sensitized solar cells (DSSCs). The DSSCs based on D1 and D2 exhibit the power conversion efficiency (PCE) of 5.16% and 4.27%, respectively. The higher PCE value of D1 based DSSC is attributed to its enhanced short circuit current (Jsc) and open-circuit voltage (Voc) and fill factor (FF) values. The electrochemical impedance spectra demonstrated shorter electron transport time, longer electron lifetime and high charge recombination resistance for DSSC based on D1, as well as larger dye loading onto TiO2 are attributed to the higher PCE. © 2015 Elsevier Ltd. All rights reserved.