Titanium Dioxide Nanorods as An Effective Blocking Layer in Solar Cells

Abstract

Blocking layer holds a crucial function in dye-sensitized solar cells (DSSC). It essentially prevents recombination from occurring between electrons in the photoanode and the oxidized dye molecules within the electrolyte. Furthermore, this layer could strengthen the connection between the conductive substrate and the photoanode layer. Herein, titanium dioxide (TiO 2) nanorods were applied as a blocking layer in DSSC, and the solar cell performance was subsequently compared with the cells containing conventional TiO 2 nanoparticles blocking layer. The TiO 2 nanorods were grown from titanium isopropoxide (TTIP) solution via the hydrothermal method for various durations, i.e., 30, 60, and 120 min. Meanwhile, the TiO 2 nanoparticles blocking layer was deposited via the wet chemistry method by hydrolyzing titanium (IV) chloride (TiCl 4). The morphology and structure of both types of blocking layers were compared, whereas the electrical properties of the solar cells were analyzed using incident photon-to-current conversion efficiency (IPCE) and current-voltage (I-V) characterization. It was found that different hydrothermal time resulted in TiO 2 nanorods with different morphologies. The application of TiO 2 nanorods blocking layer that was grown for 120 min led to a photoconversion efficiency of 3.29%, which was 8.2% and 4.4% higher than the photoconversion efficiency of cells without the blocking layer and with TiO 2 nanoparticles blocking layer, respectively. Our results indicated that the blocking layer with a TiO 2 nanorods structure could facilitate better electrons transfer than that of nanoparticles.