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Increasing the photocurrent is one of the main objectives of the current research on aqueous photovoltaic cells, the emerging green, alternative technology in solar energy conversion devices. In such a scenario, this work deals with the thorough understanding of the electrochemical and photoelectrochemical effects of the TiCl4 treatment onto TiO2 electrodes, a well-known process for traditional dye-sensitized solar cells, and here, to our knowledge, investigated for the first time in water-based systems. From the quantitative evaluation of the photoelectrochemical parameters, it emerges that the TiCl4 treatment beneficially affects the photovoltaic parameters: it doubles the sunlight conversion efficiency values, inhibits the recombination of photogenerated electrons with oxidized redox mediator ions, and ensures stable and reproducible cell performance at the laboratory scale. (C) 2019 Elsevier Ltd. All rights reserved.

Titanium tetrachloride (TiCl 4 ) treatment processed by chemical bath deposition is usually adopted as pre- and post-treatment for nanocrystalline titanium dioxide (TiO 2 ) film deposition in the dye-sensitized solar cell (DSC) technology. Pre-treatment influences positively the bonding strength between the fluorinated tin oxide (FTO) substrate and the porous TiO 2 layer, blocking the charge recombination at the interface between the conduction glass FTO and the I 3 − ions present in the I − /I 3 − red-ox couple. Additionally, TiCl 4 post-treatment is a widely known method capable of improving the performance of dye-sensitized solar cells, in particular, the photocurrent collected from the device. In this study, the influence and effect of TiCl 4 pre- and post-treatment on the TiO 2 layer is proposed and compared to the untreated film. The relative DSC devices are characterized in terms of short circuit current density, open circuit voltage, fill factor, conversion efficiency and IPCE. The dark current characteristics of cells with a treated and untreated TiO 2 layer are also shown in order to evaluate the effect of TiCl 4 pre-treatment as a blocking layer.

Techniques of TiO2 film fabrication for dye-sensitized solar cells having a conversion efficiency of global air mass 1.5 (AM 1.5, 1000 W/m(2)) solar light to electric power over 10% are reported. Newly implemented fabrication technologies consist of pre-treatment of the working photoelectrode by TiCl4, variations in layer thickness of the transparent nanocrystalline-TiO2 and applying a topcoat light-scattering layer as well as the adhesion of an anti-reflecting film to the electrode's surface. TiCl4 treatments induce improvements in the adhesion and mechanical strength of the nanocrystalline TiO2 layer. Optimization of the thickness of the TiO2 layer, acting as the working electrode, affects both the photocurrent and the photovoltage of the devices. Covering of the TiO2 photoanode by an anti-reflecting film results in enhancement of the photocurrent. Each of these components of film fabrication exerts a significant influence on the overall photovoltaic parameters of the devices resulting in improvements in the net energy conversion performance. (C) 2007 Elsevier B.V. All rights reserved.