title: A diminutive modification in arylamine electron donors: synthesis, photophysics and solvatochromic analysis--towards the understanding of dye sensitized solar cell performances.
abstract: An electron rich donor moiety plays an important role in dye sensitized solar cells (DSCs). In order to attain a suitable donor moiety for DSCs, a deeper understanding of the role of a donor moiety in the dye excited state is significant. In this context, different arylamine dye-based electron donor moieties (TRA, CRA and PyRA) were successfully synthesized and well characterized using (1)H-NMR, (13)C-NMR and EI-MS spectrometry. Their photophysical properties and solvatochromic behavior were studied using UV-visible absorption, steady state and time resolved fluorescence spectroscopic techniques. The absorption of arylamine dyes is due to intramolecular charge transfer (ICT) between the donor and rhodanine-3-acetic acid via a π-bridge, which is further confirmed by DFT calculations. Lippert-Mataga analysis on the solvatochromic data implies that these molecules are more polar in the excited state, which is additional support for ICT. Furthermore, nanocrystalline TiO2-based dye sensitized solar cells (DSCs) were fabricated using these dyes to investigate the influence of donor moieties on their photovoltaic performance. The overall power conversion efficiencies of 2.57%, 1.68% and 1.25% were obtained for the TRA, PyRA and CRA dyes, respectively. The enhanced power conversion efficiency of TRA is due to a longer lifetime of injected electrons as demonstrated by the electrochemical impedance spectroscopy (EIS) measurements.
authors.affiliation: National Centre for Ultrafast Processes, University of Madras, Taramani Campus, Chennai 600 113, Tamil Nadu, India. akathir23@hotmail.com.
authors.forename: Venkatesan
authors.initials: V
authors.lastname: Srinivasan
authors.affiliation: Department of Chemistry, Loyola College, Chennai 600 034, Tamil Nadu, India.
authors.forename: Murugesan
authors.initials: M
authors.lastname: Panneer
authors.affiliation: Department of Chemistry, Loyola College, Chennai 600 034, Tamil Nadu, India.
authors.forename: Madhavan
authors.initials: M
authors.lastname: Jaccob
authors.affiliation: Nanomaterials and Solar Energy Conversion Laboratory, Department of Chemistry, National Institute of Technology, Tiruchirappalli 620 015, Tamil Nadu, India.
authors.forename: Nagaraj
authors.initials: N
authors.lastname: Pavithra
authors.affiliation: Nanomaterials and Solar Energy Conversion Laboratory, Department of Chemistry, National Institute of Technology, Tiruchirappalli 620 015, Tamil Nadu, India.
authors.forename: Sambandam
authors.initials: S
authors.lastname: Anandan
authors.affiliation: National Centre for Ultrafast Processes, University of Madras, Taramani Campus, Chennai 600 113, Tamil Nadu, India. akathir23@hotmail.com.
authors.forename: Arunkumar
authors.initials: A
authors.lastname: Kathiravan