Enhanced photovoltaic performance of cross-linked ruthenium dye with functional cross-linkers for dye-sensitized solar cell

Abstract

Photovoltaic performance of cross-linkable Ru(2,2′-bipyridine-4,4′-bicarboxylic acid)(4,4′-bis((4-vinyl benzyloxy)methyl)-2, 2′-bipyridine)(NCS)2 (denoted as RuS dye) adsorbing on TiO2 mesoporous film was enhanced by polymerizing with either ionic liquid monomer, 1-(2-acryloyloxy-ethyl)-3-methyl-imidazol-1-ium iodide (AMImI), to form RuS-cross-AMImI or di-functional acrylic monomer with ether linkage, triethyleneglycodimethacrylate (TGDMA), to form RuS-cross-TGDMA. Their cross-linking properties were investigated by UV-vis spectroscopy by rinsing with 0.1N NaOH aqueous solution. The power conversion efficiencies (PCEs) of dye-sensitized solar cells (DSSCs) with RuS-cross-AMImI and RuS-cross-TGDMA both reached over 8% under standard global air mass 1.5 full sunlight. The increased PCE for DSSCs with RuS-cross-AMImI comparing with cross-linked RuS was attributed to the I- counterion of AMImI increasing the charge regeneration rate of RuS dye, whereas that with RuS-cross-TGDMA was attributed to the Li+ coordination property of TGDMA. The photovoltaic performance of RuS-cross-TGDMA was also slightly better than that of RuS-cross-AMImI because of higher open-circuit photovoltage (Voc) and short-circuit photocurrent (Jsc). Its higher Voc was supported by the Bode plot of impedance under illumination and Nyquist plots at dark, whereas higher Jsc was supported by the incident monochromatic photon-to-current conversion efficiency spectra and charge extraction experiments. Copyright © 2013 John Wiley & Sons, Ltd.