CdS quantum dot-sensitized solar cells based on nano-branched TiO2 arrays
1 School of Physics and State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, People's Republic of China
2 School of Information Science and Engineering, Shandong University, Jinan 250100, People's Republic of China
3 Department of Mechanical and Materials Engineering, Portland State University, P.O. Box 751, Portland, OR 97207-0751, USA
Nanoscale Research Letters 2014, 9:107 doi:10.1186/1556-276X-9-107Published: 4 March 2014
Nano-branched rutile TiO2 nanorod arrays were grown on F:SnO2 conductive glass (FTO) by a facile, two-step wet chemical synthesis process at low temperature. The length of the nanobranches was tailored by controlling the growth time, after which CdS quantum dots were deposited on the nano-branched TiO2 arrays using the successive ionic layer adsorption and reaction method to make a photoanode for quantum dot-sensitized solar cells (QDSCs). The photovoltaic properties of the CdS-sensitized nano-branched TiO2 solar cells were studied systematically. A short-circuit current intensity of approximately 7 mA/cm2 and a light-to-electricity conversion efficiency of 0.95% were recorded for cells based on optimized nano-branched TiO2 arrays, indicating an increase of 138% compared to those based on unbranched TiO2 nanorod arrays. The improved performance is attributed to a markedly enlarged surface area provided by the nanobranches and better electron conductivity in the one-dimensional, well-aligned TiO2 nanorod trunks.