title: Impact of the different electron-releasing subunits on the dye-sensitized solar cell performance of new triphenylamine-benzimidazole based molecules.
abstract: New triphenylamine-benzimidazole type small molecules with different electron-releasing groups were designed and synthesized to investigate their photovoltaic performances in dye sensitized solar cells (DSSCs). Their good visible absorptions covering the 400-535 nm in addition to suitable lowest unoccupied molecular orbital (LUMO) energy levels between -3.03 and -3.11 eV make good candidates them for DSSC devices. Fluorescence quenching studies of the dyes with pristine titania support the good electron injection to conduction band of TiO2. Time resolved measurements of the dyes in solutions indicate the occurence of charge generation during the excited state. One of the used dyes in DSSC devices, TPA5a, carrying a methoxy group in triphenylamine part of the structure, gave much higher power conversion efficiency (PCE) value of 4.31% as compared to the other derivatives. Device fabricated from TPA5a dye gives good external quantum efficiency (EQE) value above 70% at 460 nm. Also, electron impedance spectroscopy (EIS) analysis of the devices gives a good explanation of the understanding of the cell performances.
authors.affiliation: Department of Chemistry, Faculty of Arts and Science, Celal Bayar University, Yunus Emre, 45140 Manisa, Turkey. Electronic address: haluk.dincalp@cbu.edu.tr.
authors.forename: Haluk
authors.initials: H
authors.lastname: Dinçalp
authors.affiliation: Department of Chemistry, Faculty of Arts and Science, Celal Bayar University, Yunus Emre, 45140 Manisa, Turkey.
authors.forename: Gözde Murat
authors.initials: GM
authors.lastname: Saltan
authors.affiliation: Solar Energy Institute, Ege University, Bornova, 35100 Izmir, Turkey.
authors.forename: Deniz
authors.initials: D
authors.lastname: Aykut
authors.affiliation: Solar Energy Institute, Ege University, Bornova, 35100 Izmir, Turkey. Electronic address: ceylan.zafer@ege.edu.tr.
authors.forename: Ceylan
authors.initials: C
authors.lastname: Zafer
keywords: Benzimidazole; Charge transfer; Dye sensitized solar cells; Electron impedance analysis; Time resolved emission spectra; Triphenylamine