Two 8 μm thick TiO2 photoelectrodes have been sensitized sep. by N719 dye mols. and CdS quantum dots for a comparison study. Photoinduced absorption (PIA) spectroscopy was employed to investigate the mechanistic properties of electrons under illumination conditions comparable to sunlight. The PIA spectrum of both electrodes (in the presence of electrolyte) is due to electrons in TiO2 and iodine radicals I2- in the electrolyte. In the absence of redox electrolyte, both electrodes show long-lived photoinduced charge-sepn. with lifetime in a millisecond range (8.5 ms for Q-dot-sensitized TiO2 and 11.5 ms for dye-sensitized TiO2).
Michael Graetzel, Shaik Mohammed Zakeeruddin, Jacques-Edouard Moser, Etienne Christophe Socie, Weiwei Zhang, Brian Irving Carlsen, Yinghui Wu, Yameng Ren, Huiyun Jiang