Electrochemical and Photoelectrochemical Properties of Screen-Printed Nickel Oxide Thin Films Obtained from Precursor Pastes with Different Compositions

Abstract

In this work we present the electrochemical and photoelectrochemical characterization of NiO thin films [thickness (l) range: 2 <= l <= 4 mu m], which have been obtained from screen-printing of three precursor-pastes. All three pastes contained preformed NiO nanoparticles [diameter ((MT SET)) range: 20 < ((MT SET)) < 50 nm], but differed for the content and nature of the acidic component. The resulting NiO samples were employed as photoactive cathodes of p-type dye-sensitized solar cells (p-DSCs). The temperature of sintering was kept below 450 degrees C to warrant mesoporosity and electrical connectivity between the nanostructured domains while maintaining a good level of adhesion on the substrate. The photoelectrochemical properties of bare and erythrosine b (ERY)-sensitized NiO in p-DSCs depended on the composition of the screen-printing paste. The NiO samples obtained from the pastes with the lowest amount of acidic component or containing the acid with the stronger character, namely HCl, gave the best performances in the corresponding p-DSCs. In the series of ERY-based p-DSCs here tested the most performing screen-printed electrode gave the largest overall conversion efficiency (eta > 0.04%) and highest external quantum efficiency (EQE > 9% at 830 nm) with respect to the p-DSCs with NiO photocathodes of similar thickness, which have been prepared via different methods of deposition. (C) 2017 The Electrochemical Society.All rights reserved

Effect of Sensitization on the Electrochemical Properties of Nanostructured NiO

“…Mesoporous NiO thin films have been deposited via screen printing of a paste containing NiO nanoparticles in accordance to the procedure reported in [36]. The scheme of preparation of the paste is reported in Table S1.…”

“…The scheme of preparation of the paste is reported in Table S1. The paste was successively screen printed onto Fluorine doped Tin Oxide (FTO)-coated glass and annealed at 450 • C in an oven, and a non-stoichiometric film of porous nickel oxide (l = 2.5 µm) was obtained [36]. The resulting film of NiO was nanostructured ( Figure 1) and was used successively as a photocathode of a p-DSC in both pristine and sensitized states.…”

“…In all the experiments, the electrolyte solution was LiClO4 0.2 M in ACN (Acetonitrile). All figures have been plotted with the application Kaleidagraph 3.6, and their photoelectrochemical characterization has been already described in previous works [36,85,86]. …”

“…Moreover, nanostructured films of NiO present solid-state electroactivity [25][26][27] due to the verification of a series of reversible electrochemical processes that switch the properties of electrical transport [28] and optical absorption [29] of the oxide itself. The optical [10][11][12][13][14]30,31], magnetic [32,33], electrochemical [34], and photoelectrochemical [35,36] properties of NiO (either in the bulk state or in the nanostructured version) are considerably altered when the surface of the oxide is dye-sensitized [37]. Such a type of electrode modification consists mainly in the impartation of additional optical absorption [38][39][40][41][42][43][44][45][46][47][48][49] and photoelectroactivity to NiO in the NIR-Vis range, i.e., in a spectral range of lower energies with 2 of 18 respect to the intrinsic optical absorption of pristine NiO (typically in the near ultraviolet (UV)) [50].…”

“…The present contribution reports a study on the electrochemical and photoelectrochemical properties of NiO thin films prepared via screen printing [36,73,74] when the NiO electrode is either in the pristine state or in the dye-sensitized version. In particular, we considered the sensitization of nanostructured NiO with a series of organic dyes, the optical absorption properties of which span the visible and (near-infrared) NIR ranges.…”