Metal Oxides for Dye‐Sensitized Solar Cells

Abstract

The incessant demand for energy forces us to seek it from sustainable resources; and concerns on environment demands that resources should be clean as well. Metal oxide semiconductors, which are stable and environment friendly materials, are used in photovoltaics either as photoelectrode in dye solar cells (DSCs) or to build metal oxide p–n junctions. Progress made in utilization of metal oxides for photoelectrode in DSC is reviewed in this article. Basic operational principle and factors that control the photoconversion efficiency of DSC are briefly outlined. The d‐block binary metal oxides viz. TiO2, ZnO, and Nb2O5 are the best candidates as photoelectrode due to the dissimilarity in orbitals constituting their conduction band and valence band. This dissimilarity decreases the probability of charge recombination and enhances the carrier lifetime in these materials. Ternary metal oxide such as Zn2SnO4 could also be a promising material for photovoltaic application. Various morphologies such as nanoparticles, nanowires, nanotubes, and nanofibers have been explored to enhance the energy conversion efficiency of DSCs. The TiO2 served as a model system to study the properties and factors that control the photoconversion efficiency of DSCs; therefore, such discussion is limited to TiO2 in this article. The electron transport occurs through nanocrystalline TiO2 through trapping and detrapping events; however, exact nature of these trap states are not thoroughly quantified. Research efforts are required not only to quantify the trap states in mesoporous metal oxides but new mesoporous architectures also to increase the conversion efficiency of metal oxide‐based photovoltaics.

Electrochemical characterization of NiO electrodes deposited via a scalable powder microblasting technique

“…Similar to the Sample A coating (Figure 7), the onset of the reduction of sintered NiO x nanoparticles (sample B) occurs at approximately 2.6 V. 9,47 However, the cathodic current density exchanged by Sample B for the NiO x reduction [potential range 1.3 -2.6 V vs Li + /Li ( Figure 8)], is generally lower than that obtained for sample A (Figure 7). Despite the larger surface area of NiO x electrodes obtained for sample B, (Figure 4b), [55][56][57][58] and for sol-gel deposited coatings, 6b,14b the current density associated with NiO x reduction [Eq. (1)] is approximately two times higher for the microblast deposited sample A, which possesses a larger particle size in the order of several microns ( Figure 2).…”

Synthesis and Structural Properties of Niobium Pentoxide Powders: A Comparative Study of the Growth Process

“…The interest in studying the Nb 2 O 5 is due to its remarkable physicochemical properties and structural isotropy suitable for a wide range of applications in the construction of gas sensing, electrochromics display and photoelectrodes, as well as in field-emission displays and microelectronics [1][2][3][4][5][6] . Studies were conducted in the past on the use of Nb 2 O 5 nanoparticles for environmental remediation in water through of photocatalytic processes.…”

A Comparative Study of Nanostructured TiO2, ZnO and Bilayer TiO2/ZnO Dye-Sensitized Solar Cells

“…Binary metal oxides such as TiO 2 , ZnO, Nb 2 O 5 , Fe 2 O 3 , ZrO 2 , Al 2 O 3 , CeO 2 and ternary compounds such as SrTiO 3 , Zn 2 SnO 4 have been tested for their use as photoelectrodes in DSSC. 3 Among them, the d-block binary metal oxides, TiO 2 , ZnO, and Nb 2 O 5 are the best candidates to be photoelectrodes due to the dissimilarity in orbitals constituting their conduction band and valence band. 3 The high efficiency of these DSSCs depends upon the effective separation and transportation of the charges generated in the dye molecules over the semiconducting nanoparticles.…”

“…3 Among them, the d-block binary metal oxides, TiO 2 , ZnO, and Nb 2 O 5 are the best candidates to be photoelectrodes due to the dissimilarity in orbitals constituting their conduction band and valence band. 3 The high efficiency of these DSSCs depends upon the effective separation and transportation of the charges generated in the dye molecules over the semiconducting nanoparticles. However, the energy conversion efficiency of DSSCs is still inferior to conventional Si and thin films solar cells.…”