Development of type I/type II hybrid dye sensitizer with both pyridyl group and catechol unit as anchoring group for type I/type II dye sensitized solar cell.
A type I/type II hybrid dye sensitizer with a pyridyl group and a catechol unit as the anchoring group has been developed and its photovoltaic performance in dye sensitized solar cells (DSSCs) is investigated. The sensitizer has the ability to adsorb on a TiO2 electrode through both the coordination bond at Lewis acid sites and the bidentate binuclear bridging linkage at Bronsted acid sites on the TiO2 surface, which makes it possible to inject an electron into the conduction band of the TiO2 electrode by the intramolecular charge transfer (ICT) excitation (type I pathway) and by the photoexcitation of the dye to TiO2 charge transfer (DTCT) band (type II pathway) It was found that the type I/type II hybrid dye sensitizer adsorbed on TiO2 film exhibits a broad photoabsorption band originating from ICT and DTCT characteristics. Here we reveal the photophysical and electrochemical properties of the type I/type II hybrid dye sensitizer bearing a pyridyl group and a catechol unit, along with its adsorption modes onto TiO2 film, and its photovoltaic performance in type I/type II DSSC, based on optical (photoabsorption and fluorescence spectroscopy) and electrochemical measurements (cyclic voltammetry) density functional theory (DFT) calculation, FT IR spectroscopy of the dyes adsorbed on TiO2 film, photocurrent voltage (I V) curves, incident photon to current conversion efficiency (IPCE) spectra, and electrochemical impedance spectroscopy (EIS) for DSSC.
Physical chemistry chemical physics PCCP