Photoacoustic spectroscopy of TiO2 nanotube electrode adsorbed with CdSe quantum dots and its photovoltaic properties

We report on the optical absorption properties and photovoltaic characteristics of nanotube (NT) TiO2 electrodes adsorbed with CdSe quantum dots (QDs), and compared them with those of nanoparticle (NP) TiO2 electrodes adsorbed with CdSe QDs. The CdSe QDs were grown directly on the TiO2 electrodes by the successive ionic layer adsorption and reaction (SILAR) method. The width of the exponential tail (E-U) of the photoacoustic (PA) spectra of the NT-TiO2 electrodes without CdSe QDs was more than 3 times lower than that of NP-TiO2. The results imply that the surface defects and disorder in NT-TiO2 are fewer than those in NP-TiO2. From the photovoltaic characteristics, we found that the shunt resistance (R-sh) of the CdSe-QD-sensitized NT-TiO2 solar cell was much higher than that of the CdSe-QD-sensitized NP-TiO2 solar cell, indicating the surface defects and disorder in NT-TiO2 were fewer than those in NP-TiO2. (C) 2014 The Japan Society of Applied Physics