The effect of titanium (IV) chloride surface treatment to enhance charge transport and performance of dye-sensitized solar cell

• Main Authors: N. Fadzilah M. Sharif, Suhaidi Shafie, M.Z.A. Ab. Kadir, W.Z. Wan Hasan, Muhammad Norhaffis Mustafa, Buda Samaila
• Format: Article
• Language: English
• Published: Elsevier 2019-12-01
• Series: Results in Physics
• Online Access: http://www.sciencedirect.com/science/article/pii/S2211379719320704

In this study, the photovoltaic and electrochemical characteristics of the dye-sensitised solar cell (DSSC) after titanium (IV) chloride (TiCl4) treatment on a TiO2 photoelectrode were investigated. Photoelectrodes of untreated, pre-TiCl4 and post-TiCl4 treatment were prepared to form a complete DSSC. The photoelectrode was sensitised in 40 mM of TiCl4 solution at 80 °C for 30 min, and then it is sintered at 500 °C. The morphology of photoelectrodes has been studied using FESEM, and it was found that, after TiCl4 treatment, the particle necking and particle size of TiO2 nanoparticles were increased significantly. Therefore, it improved the electron transfer path on the TiO2 layer. Subsequently, the light absorption intensity after post-TiCl4 treatments was increased due to strong adhesion and homogeneity of the TiO2 layer on the FTO substrate, which results in higher current density and photon-conversion efficiency by 18.95 mAcm−2 and 8.03% when compared to an untreated electrode at 12.1 mAcm−2 and 4.08% (increment of 56.7% and 96.9%), respectively. Electrochemical impedance spectroscopy used to study the internal electrochemical characteristics of DSSC after the treatment. Thus, it proves that the treatment suppresses the charge recombination between TiO2 and the electrolyte interface by increasing charge transfer resistance after post-TiCl4 treatment by 24.06 Ω from 16.11 Ω for untreated photoelectrodes (increment of 49.39%). The electron lifetime also improved from 0.4 to 1.59 ms, which results in the enhancement of charge collection efficiency after post-treatment by 31.09% compared to the untreated electrode. Improvement of charge collection efficiency indicated that the TiCl4 treatment had played an important role in charge separation and charge collection on the TiO2 and electrolyte interface of DSSC. Keywords: Charge collection efficiency (CCE), Charge transport, DSSC surface treatment