Synthesis And Photovoltaic Performance Of Dyes Based On Indoline And The Synthesis Of Porphrin

Dye–sensitized solar cells (DSCs) have been considered to be a credible alternative toconventional inorganic silicon–based solar cells because of their ease of fabrication, highefficiency and cost–effectiveness since the report by O’Regan and Gr tzel. To acquire highsolar power conversion efficiency（η）, lots of research efforts are concentrated on designingand synthesizing new photosensitizers as well as deeply understanding of essential limitingsurface processes in DSCs. Among these synthesized photosensitizers, arylamine organicsensitizers with robust availability, widespread high molar extinction coefficients andstructural tuning easily, have received great attention.Three new indoline dyes XS45-XS47have been synthesized，By comparison theinfluence fluorene unit and tert-butylbenzene to the charge recombination introduction offluorine unit with larger π conjugation into the indoline unit promotes red-shifting inabsorption spectra and strengthen maximum molar absorption coefficients (ε) and remarkablyretards the charge recombination at the titania/electrolyte interface. XS45and XS46withD-A-π-A structure, the introduction of benzothiadiazole (BTD) in spacer leads to extendedbroad spectral response range.We further examined the J-V curves of DSCs in conjunction with a cobalt electrolyte (E2),A similar trend in PCE can be found for the cobalt dyes, namely, XS45> XS47> XS46. Incomparison with iodine cells, all the cobalt cells exhibit a significantly declined JSCandremarkably rised VOC. It is found that regardless of the electrolyte selection, the VOCvalues ofXS46are lower than those of XS47/XS45. The electron lifetimes at open circuit (τ), measuredby controlled intensity modulated photovoltage spectroscopy (IMVS), can be obtained byfitting either the real or imaginary part of the IMVS response. The enhancement of VOCvaluefor XS45in comparison to XS46is largely because of the increased electron lifetimes (i.e.,retarded electron recombination rate) rather than the different positions of the conductionband edge of TiO2. Similarly, the significantly VOCenhancement of XS47as compared toXS46is primarily attributed to the improvement in the lifetime.The higher JSCvalues of6μm cells related to that of3μm cells can be caused by theincreased amount of adsorbed dyes. The notably decreased JSCof12μm cells has beencorrelated to the mass transport and recombination limitations associated with the polypyridylcobalt redox shuttles. On the other hand, the VOCbecomes lower along with the increase offilm thickness, due to augmentation of the surface area, which provides additionalcharge-recombination sites and enhances the dark current. In contrast to the iodine cells, thePCE obtained with the cobalt electrolyte are affected in a different way by the film thickness.Despite the better light harvesting efficiency obtained using thicker films, it results of lowerJSCvalues.