Characterization of charge transport properties of a 3D electrode for dye-sensitized solar cells

Abstract

Electron transport and recombination in three-dimensionally-ordered (3D-ordered) structure electrodes were investigated using intensity-modulated photocurrent and photovoltage spectroscopy. The surface-modified TiO2 inverse opal structure was applied as a 3D electrode. The morphology, crystalline structure and surface states of the 3D-ordered structure were characterized by SEM, TEM and XPS and compared to those of the conventional nanoparticulate TiO2 structure. The performance of the 3D electrode was also evaluated by comparing the transport time and recombination lifetime to those of the conventional electrodes. Remarkably, the recombination lifetime in inverse opal was found to be greater than in nanocrystalline TiO2 by 4.3-6.2 times, thus improving the electron collection efficiency by 10%. Comparing the photovoltaic performance, although the dye adsorption of the 3D-ordered porous electrode is lower, the electrode achieves a photocurrent density comparable to that of a nanoparticulate TiO2 electrode due to the higher light scattering as well as the higher collection efficiency.

A colloidoscope of colloid-based porous materials and their uses

“…One of the primary reasons hierarchical CBPM are used as electrodes is their high surface area, with a higher active area for a given volume of material. High surface area allows for easy access to active materials in batteries 75,421,423,426,[428][429][430][431] and fuel cells, 432,433 improving energy density. It also leads to higher dye loading, and thus increased light absorption and higher rates, in dye-sensitized solar cells.…”

“…430 Ordered, inverse structures have been particularly well investigated as a means of controlling ion transport, for example in Li-ion batteries, 26,428,466 Li-air batteries, 431 dye-sensitized solar cells (DSSC), 450 and fuel cells. 432,433 These colloid-templated structures have also been used as separators in batteries 184 and fuel cells 434 due to their ability to control ion diffusion. Capacitors also benefit from the control over diffusion, because high surface area increases the capacitance, but it can also cause very high charging times.…”

Highly improved photocurrents of dye-sensitized solar cells containing ultrathin 3D inverse opal electrodes sensitized with a dithienothiophene-based organic dye

“…15 Second, the IO structure electrodes exhibited rapid charge transport, which extends the electronhole recombination lifetime during DSC applications by a factor of 6 relative to conventional mesoporous lms. 16 Here, using a 3.5 mm thick Carbz-PAHTDTT-sensitized IO TiO 2 electrode lm, we obtained a photocurrent density of 11.23 mA cm À2 in their DSC application. This photocurrent value was approximately 1.5 times higher compared to the N719 dye-sensitized IO electrode DSCs.…”

Facile fabrication of sub-100 nm mesoscale inverse opal films and their application in dye-sensitized solar cell electrodes

“…Additionally, the connected structure of IO imparts it with better electron transport properties compared to those of disordered conventional electrode materials. In previous studies, our group has observed that the recombination lifetime of DSCs containing TiO 2 -based IO electrodes was 6-times longer than that of the TiO 2 NP electrodes 15 . Moreover, the ordered macroporous structures of IO make it easier to fill its pores with electrolyte solutions or polymeric electrolytes 16 .…”

“…Most of the IO fabricated in the aforementioned studies mentioned had pore sizes in the range of several hundred nanometers to a few micrometers. IO films with 550–600 nm diameter macropores have a specific area, as evaluated by the dye adsorption density, approximately 10 times lower than that of NP films 15 . Some authors have proposed techniques for decorating the surface of IO frameworks with nanoparticles or nanorods to overcome this issue.…”