Photoinduced electron transfer reactions of pyranine with benzoquinone and titanium dioxide

The fluorescence quenching of pyranine by benzoquinone in acetonitrile medium was studied using steady-state and time-resolved fluorescence techniques. The quenching process was characterized by a Stern-Volmer plot, which displayed a linear aspect. From the linear plot, the bimolecular quenching rate constant was obtained. The obtained rate constants are within diffused controlled limits. The results show that benzoquinone can efficiently quench the fluorescence of pyranine with dynamic quenching rate constants in the order of 10¹⁰ M^-1 s^-1 , suggesting that the pyranine can act as a good electron donor for photoinduced electron transfer in artificial photosynthesis and organic solar cells. In addition, the electron injection dynamics of a pyranine/titanium dioxide semiconductor film was also investigated and electron injection from the excited state pyranine into the conduction band of titanium dioxide is suggested. These preliminary results hold promise for the possibility of using pyranine in dye-sensitized solar cells. Copyright © 2016 John Wiley & Sons, Ltd.