Electron-Selective Layers for Dye-Sensitized Solar Cells Based on TiO₂ and SnO₂

Abstract

Titanium dioxide (anatase, rutile) and quasi-amorphous tin dioxide are prepared on F-doped SnO2 in the form of dense thin films, which can serve as electron-selective layers in perovskite solar cells and dye-sensitized solar cells (DSSCs). The present study brings new data about electronic and electrochemical properties of these films at the authentic conditions occurring in a dye-sensitized solar cell (DSSC). Hydrolysis of TiCl4 provides pure rutile TiO2 at low temperatures, but TiO2 (anatase) grows in these layers upon calcination. In acetonitrile medium, the flat band potential of TiO2 (rutile) is more negative than that of TiO2 (anatase). This is opposite ordering to that observed in aqueous media. The energy of conduction band minimum of TiO2 (anatase) equals −4.15 ± 0.07 eV at the conditions mimicking the DSSC’s environment. Electrochemical reductive doping of SnO2 provides a material with the most negative flat band potential and the largest overpotential for the reduction of I3 –, Co­(bpy)3 3+, and Cu­(tmby)2 2+. Voltammetric screening of all the electrode materials in six different electrolyte solutions, relevant to DSSC applications, gives salient information about the mediator type and effects of calcination and the addition of 4-tert-butylpyridine. These data provide novel inputs for optimization of DSSCs and for perovskite photovoltaics, too.

Magnetron Sputtered Electron Blocking Layer as an Efficient Method to Improve Dye-Sensitized Solar Cell Performance

“…Because the main factor for this parameter is the difference between the mesoporous TiO2 and redox electrolyte energy band levels [36], the n-type metal oxide thin film on the FTO should not have a strong effect on the Uoc. As recently shown, a thin layer of TiO2 on the FTO electrode significantly increases the onset of cathodic dark current, pointing to the increase in a potential barrier to the electron transfer from the FTO to the electrolyte [37]. In our studies the presence of the electron blocking layer significantly increased the short circuit current (Isc) and, as a consequence, also increased the fill factor (FF).…”

Blue Photosensitizer with Copper(II/I) Redox Mediator for Efficient and Stable Dye‐Sensitized Solar Cells

“…Electrochemical Measurements: Electrochemical experiments were carried out according to the previously reported method. [42] The working electrode was mesoporous TiO 2 (4 µm thick film) deposited directly on FTO, i.e., without any underlayer.…”

Experimental investigation of hydrogen insertion in copper oxide on photovoltaic performance of p‐type dye‐sensitized solar cell

“…The value of the capacitance interface was measured in the potential range of 0.3 to 1.3 V, with a 50 mV potential step at 1000 Hz and an amplitude of 20 mV AC potential. All potentials were referenced to the saturated hydrogen electrode (SHE), assuming the standard redox potential of Fc + /Fc equal to 0.624 V vs SHE 30,31 …”