Acid Treatment of Titania Pastes to Create Scattering Layers in Dye-Sensitized Solar Cells

Park

ACS Appl. Mater. Interfaces

et al. 2013

A facile method for increasing the reaction rate of dye adsorption, which is the most time-consuming step in the production of dye-sensitized solar cells (DSSCs), was developed. Treatment of a TiO2 photoanode with aqueous nitric acid solution (pH 1) remarkably reduced the reaction time required to anchor a carboxylate anion of the dye onto the TiO2 nanoparticle surface. After optimization of the reaction conditions, the dye adsorption process became 18 times faster than that of the conventional adsorption method. We studied the influence of the nitric acid treatment on the properties of TiO2 nanostructures, binding modes of the dye, and adsorption kinetics, and found that the reaction rate improved via the synergistic effects of the following: (1) electrostatic attraction between the positively charged TiO2 surface and ruthenium anion increases the collision frequency between the adsorbent and the anchoring group of the dye; (2) the weak anchoring affinity of NO3(-) in nitric acid with metal oxides enables the rapid coordination of an anionic dye with the metal oxide; and (3) sufficient acidity of the nitric acid solution effectively increases the positive charge density on the TiO2 surface without degrading or transforming the TiO2 nanostructure. These results demonstrate the developed method is effective for reducing the overall fabrication time without sacrificing the performance and long-term stability of DSSCs.

Section: ■ Results and Discussionmentioning

confidence: 62%

Rapid Dye Adsorption via Surface Modification of TiO₂ Photoanodes for Dye-Sensitized Solar Cells

Park

ACS Appl. Mater. Interfaces

et al. 2013

Solar Energy Materials and Solar Cells

“…The recorded increase in reflectance is proportional to the wavelength (Figure 1b, Figure 2a), and higher for longer exposure to nitric acid ( Figure S2a, Supporting Information). Surface modifications of titania pastes upon treatment with nitric acid have been previously shown to increase the absorbance in the 400-800 nm wavelength range, enhancing the light-harvesting effectiveness of DSSCs, and the incident photon-to-current conversion efficiency because of increased forward scattering [41]. It was also found that the NO3 -ions produced after immersion in HNO3 may coat the TiO2 and block the path of backward electron transfer [42].…”

Section: Discussionmentioning

confidence: 99%

TiO2 alterations with natural aging: Unveiling the role of nitric acid on NIR reflectance

Paolini

Sleiman

Pedeferri

et al. 2016

The development of photoactive materials with self-cleaning and depolluting qualities is a hot topic in materials science, given their impact on several technologies, in a wide range of contexts of applications. Anatase phase titanium dioxide (TiO2) is the largest used photocatalyst, with increasing applications ranging from air quality control to renewable energies, to green building materials for zero energy communities. Yet, it is partially transmissive in the near infrared (NIR), which negatively affects the solar reflectance of TiO2 containing materials. In this contribution we describe an unexpected increase in anatase near infrared (NIR) reflectance observed during environmental exposure. We unveil its complex mechanisms, based on the contact with nitric acid generated by NOx photocatalytic degradation, which causes partial reduction and decrease in crystallinity to TiO2. This may open the way for introducing multiple environmentally beneficial effects on TiO2 pollutants degradation, self-cleaning, and energy performance.

International Journal of Photoenergy

“…The aim of this current study is to develop techniques which could allow in situ measurement of the corrosion rates of metals in sealed cells, without the need for ex situ sampling of the DSC electrolyte. We have adapted two techniques used in other areas of DSC study, such as dye uptake kinetics, namely, diffuse reflectance UV-visible spectrophotometry (DR-UV/Vis) and time-lapse digital photography [15][16][17][18]. As both techniques employ thin electrolyte layers in contact with metal surfaces, any interaction of the coloured triiodide species with the metal can be rapidly quantified.…”

Section: Introductionmentioning

confidence: 99%

Corrosion Monitoring of Flexible Metallic Substrates for Dye-Sensitized Solar Cells

Watson

Reynolds

Wragg

et al. 2013

Self Cite

Two techniques for monitoring corrosion within a dye-sensitized solar cell (DSC) system are presented, which enable continuous, high sensitivity, in situ measurement of electrolyte breakdown associated with DSCs fabricated on metals. The first method uses UV/Vis reflectance spectrophotometry in conjunction with encapsulation cells, which incorporate a 25 μm thick electrolyte layer, to provide highly resolved triiodide absorption data. The second method uses digital image capture to extract colour intensity data. Whilst the two methods provide very similar kinetic data on corrosion, the photographic method has the advantage that it can be used to image multiple samples in large arrays for rapid screening and is also relatively low cost. This work shows that the triiodide electrolyte attacks most metals that might be used for structural applications. Even a corrosion resistant metal, such as aluminium, can be induced to corrode through surface abrasion. This result should be set in the context with the finding reported here that certain nitrogen containing heterocyclics used in the electrolyte to enhance performance also act as corrosion inhibitors with significant stabilization for metals such as iron. These new techniques will be important tools to help develop corrosion resistant metal surfaces and corrosion inhibiting electrolytes for use in industrial scale devices.