Improving Microstructured TiO₂ Photoanodes for Dye Sensitized Solar Cells by Simple Surface Treatment

Abstract

TiCl4 surface treatment studies of porous electrode structure of TiO2 aggregates synthesized using an acidic precursor and CTAB as a templating agent are carried out in order to understand and improve upon recombination kinetics in the photonanode film matrix, together with enhancing the intrinsic light scattering. The key beneficial features of the photoanode included high surface roughness, necessary for superior dye adsorption, nanocrystallite aggregates leading to diffuse light scattering within the film matrix, and a hierarchical macro‐ and mesopore structure allowing good access of electrolyte to the dye, thereby assisting in dye regeneration (enhanced charge transfer). Pre‐treatment of the TiO2 electrodes reduced recombination at the fluorine‐doped tin oxide (FTO)/electrolyte interface. The post‐treatment study showed enhanced surface roughness through the deposition of a thin overlayer of amorphous TiO2 on the film structure. This led to a notable improvement in both dye adsorption and inherent light scattering effects by the TiO2 aggregates, resulting in enhanced energy harvesting. The thin TiO2 overlayer also acted as a barrier in a core‐shell configuration within the porous TiO2 matrix, and thereby reduced recombination. This allowed the hierarchical macro‐ and mesoporosity of the film matrix to be utilized more effectively for enhanced charge transfer during dye regeneration. Post‐treatment of the aggregated TiO2 matrix resulted in a 36% enhancement in power conversion efficiency from 4.41% of untreated cells to 6.01%.

Multidimensional ZnO Architecture for Dye‐Sensitized Solar Cells with High‐Efficiency up to 7.35%

“…[ 22 ] Specifi cally, a ZnO nanocrystallite compact layer with thickness of around 100 nm was subsequently deposited on the substrate via a spin-coating method before doctor-blading the ZnO NA fi lm. The photovoltaic performance of ZnO NA/NS−020 cell with compact layer (denoted as NA/ NS−020/CL cell) is given in Figure 3 , which shows a noticeable improvement of J SC from 17.90 to 20.72 mA cm −2 , leading to an outstanding PCE up to 7.35%.…”

Synthesis of nanobranched TiO2 nanotubes and their application to dye-sensitized solar cells

“…In general, the formation of seed layer is a starting point to grow a certain material, being an essential step for the synthesis of a material. Considering that the orientation of ZnO seed layer directly determines the orientation of the nanorods, that is to say, the aligned ZnO seed layer makes the aligned ZnO nanorod on the substrate, while a powder formed ZnO seed layer rests at all angles on the substrate [12], in the similar fashion, the TiO 2 seeds on the high aspect-ratio TONT substrate exist preferentially at all angles because the TiCl 4 treatment is facilitated as a seed solution that forms the powder formed TiO 2 nanoparticles [13]. Upon this substrate, the TiO 2 nanorods concurrently grow at all angles, finally forming the nanobranched TiO 2 structure.…”

“…In addition to the diffraction peaks corresponding to the Ti substrate, the diffraction peaks of TONT ( Fig. 2(a)) can be indexed as those of anatase (101), (200), (004), (105), (211) planes according to the JCPDS-84-1286 [13]. The nanobranched TONT contained extra diffraction peaks manifesting the presence of rutile (110) and (200) planes, which is in good agreement with reported data of JCPDS-88-1175 [15].…”

Dual interfacial modifications of hierarchically structured iodine-doped ZnO photoanodes for high-efficiency dye-sensitized solar cells

“…a ZnO CL and a TiO 2 PL into one electrode film. Such dual optimized steps indeed have been realized in TiO 2 -based DSCs [22,23], but have not been documented in ZnO-based DSCs so far. Moreover, the stability of ZnO cell is also thought to be improved because that TiO 2 PL could effectively prevent ZnO from reacting with dye.…”