A novel 2,7-diaminofluorene-based organic dye (coded as JD2) with the diarylaminofluorene unit as the electron donor and the cyanoacrylic acid as the acceptor as well as anchoring group in a donor-pi-donor-pi-acceptor architecture is used in a dye-sensitized solar cell (DSSC). The TiO2 film thickness and the dye soaking time are optimized, and a coadsorbate of bis-(3,3-dimethyl-butyl)-phosphinic acid (DINHOP) is added to the dye solution to reform the cell performance. Effects of the additives, N-methylbenzimidazole (NMBI), guanidinium thiocyanate (GuSCN) or 4-tert-butylpyridine (TBP) in the electrolyte on the photovoltaic performance of the DSSC are studied. Effects of change of DINHOP concentration in JD2 dye solution, change of ratio of Lil to 1,2-dimethyl-3-propylimidazolium iodide (DMPII), and change of concentration of 12 in the electrolyte on the photovoltaic performance of the DSSC are studied. A light-to-electricity conversion efficiency (eta) of 6.31% is achieved for the JD2 dye-based DSSC, which is one of the best efficiencies for a cell with an organic dye. Explanations are made with electrochemical impedance spectra (EIS), laser-induced photo-voltage transients, and incident photo-to-current conversion efficiency (IPCE) curves. (C) 2012 Elsevier B.V. All rights reserved.