Core–shell nanoporous electrode for dye sensitized solar cells: the effect of shell characteristics on the electronic properties of the electrode

Diamant, Y.; Chappel, S.; Chen, S.G.; Melamed, Ophira; Zaban, Arie

doi:10.1016/j.ccr.2004.03.003

Cited by 256 publications

(241 citation statements)

References 28 publications

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“…Several studies show that high band-gap metal-oxide materials such as In 2 O 3 , ZrO 2 , Al 2 O 3 , Nb 2 O 5 , Ga 2 O 3 and SiO 2 could reduce recombination in DSSCs by blocking the back-transfer of electrons and thus preventing the recombination of electrons with either oxidized dye molecules or the oxidized redox couple (the latter one is thought to be particularly dominant in device performance degradation) [17][18][19][20][21][22] or reducing the density of surface trap states on the TiO 2 surface. 18,23 In addition, some studies demonstrate that metal-oxides like Nb 2 O 5 , SrTiO 3 , ZrO 2 and Al 2 O 3 can contribute to device performance enhancement by inducing a surface dipole at the metal-oxide/dye interface, leading to a negative shi in the TiO 2 conduction band 24 and an enhancement in the injection yield of photo-induced electrons. 25 In addition to the improved electrodynamics at the interface, improvement in device performance has also been related to dye adsorption enhancement.…”

Section: -14mentioning

confidence: 99%

Surface engineered angstrom thick ZnO-sheathed TiO₂ nanowires as photoanodes for performance enhanced dye-sensitized solar cells

Ghobadi

Okyay

2014

J. Mater. Chem. A

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This paper presents a systematic study on the effects of angstrom-thick atomic layer deposited (ALD) ZnO sheaths on hydrothermally-grown TiO 2 nanowires (NWs) used as photoanodes in dye-sensitized solar cells (DSSCs). We designed, synthesized and characterized the samples prepared using different numbers of ZnO cycles and compared their photovoltaic (PV) performances. The device consisting of TiO 2 NWs coated with the optimum thickness (two cycles) of ZnO shell exhibits a three-fold increase in efficiency compared to a control reference device. This paper reports results and features that demonstrate the passivation of surface state traps upon deposition of ZnO shells. While this passivation of surface traps provides a reduction in the back-reactions of the surface state mediated electrons (K trap ET ), it is speculated that ZnO-induced surface band bending (SBB) substantially reduces the recombination rate of the device by reducing the recombination rate of the conduction band (CB) electrons (K CB ET ). Moreover, an enhancement in the amount of dye uptake for ZnO-coated TiO 2 samples is observed and explained with the isoelectric point (IEP) concept. In spite of the excellent PV power conversion efficiencies achieved by the first ZnO cycles, thicker layers impede the electron injection rate, reducing the efficiency of the device by capturing the photogenerated dye electrons in ZnO quantum wells. Here, we investigate the mechanisms contributing to this unprecedented change and correlate them with the enhancement in device efficiency.

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Section: -14mentioning

confidence: 99%

Surface engineered angstrom thick ZnO-sheathed TiO₂ nanowires as photoanodes for performance enhanced dye-sensitized solar cells

Ghobadi

Okyay

2014

J. Mater. Chem. A

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“…In addition to suppressing recombination, a shell can raise cell V OC directly if it has a more negative conduction band edge than the core oxide or if it creates a dipole at the core-shell interface that shifts the band edge of the core upward in energy. 30 Applying the core-shell concept to a nanowire photoelectrode provides a means to increase τ n and L n by augmenting the radial surface field that reflects electrons from the nanowireelectrolyte interface.…”

Section: Introductionmentioning

confidence: 99%

ZnO−Al₂O₃ and ZnO−TiO₂ Core−Shell Nanowire Dye-Sensitized Solar Cells

et al. 2006

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We describe the construction and performance of dye-sensitized solar cells (DSCs) based on arrays of ZnO nanowires coated with thin shells of amorphous Al 2 O 3 or anatase TiO 2 by atomic layer deposition. We find that alumina shells of all thicknesses act as insulating barriers that improve cell open-circuit voltage (V OC ) only at the expense of a larger decrease in short-circuit current density (J SC ). However, titania shells 10-25 nm in thickness cause a dramatic increase in V OC and fill factor with little current falloff, resulting in a substantial improvement in overall conversion efficiency, up to 2.25% under 100 mW cm -2 AM 1.5 simulated sunlight. The superior performance of the ZnO-TiO 2 core-shell nanowire cells is a result of a radial surface field within each nanowire that decreases the rate of recombination in these devices. In a related set of experiments, we have found that TiO 2 blocking layers deposited underneath the nanowire films yield cells with reduced efficiency, in contrast to the beneficial use of blocking layers in some TiO 2 nanoparticle cells. Raising the efficiency of our nanowire DSCs above 2.5% depends on achieving higher dye loadings through an increase in nanowire array surface area.

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“…Chen et al [34] found improved DSSC performance with Nb2O5-coated TiO2 electrodes. Chen et al [37,38] compared the effects of SrTiO3 and Nb2O5 shells on the electronic properties of TiO2 cores. They found that in both cases, Voc increased.…”

Section: Blocking Layermentioning

confidence: 99%

Improving the efficiency of dye-sensitized solar cells by photoanode surface modifications

Sun

Dou

et al. 2016

Sci. China Mater.

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Dye-sensitized solar cells (DSSCs) provide a promising alternative solar cell technology because of their high efficiency, environmental friendliness, easy fabrication, and low cost. Power conversion efficiency is an important parameter to measure the performance of DSSCs, but the severe charge recombination that occurs at the photoanode hinders the future improvement of power conversion efficiency. Therefore, one of the key goals for achieving high efficiency is to reduce the energy loss caused by the unwanted charge recombination at various interfaces. From this perspective, surface modification of the photoanode is the simplest method among the various approaches available in the literature for enhancing the performance of DSSCs by inhibiting the interfacial charge recombination. After some brief notes on DSSCs, in this review, we present a comprehensive discussion on surface modifications of different photoanodes that have been adopted in the literature not only for reducing recombination but also for enhancing light harvesting. Depending on the electrode materials, we discuss surface modifications of binary oxides such as TiO2 and ZnO and ternary oxides, including Zn2SnO4, SrSnO3, and BaSnO3. We also talk about methods of surface modification and the materials suitable for surface treatment. Finally, we end with a brief future outlook of DSSCs.

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Core–shell nanoporous electrode for dye sensitized solar cells: the effect of shell characteristics on the electronic properties of the electrode

Cited by 256 publications

References 28 publications

Surface engineered angstrom thick ZnO-sheathed TiO₂ nanowires as photoanodes for performance enhanced dye-sensitized solar cells

Surface engineered angstrom thick ZnO-sheathed TiO₂ nanowires as photoanodes for performance enhanced dye-sensitized solar cells

ZnO−Al₂O₃ and ZnO−TiO₂ Core−Shell Nanowire Dye-Sensitized Solar Cells

Improving the efficiency of dye-sensitized solar cells by photoanode surface modifications

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Core–shell nanoporous electrode for dye sensitized solar cells: the effect of shell characteristics on the electronic properties of the electrode

Cited by 256 publications

References 28 publications

Surface engineered angstrom thick ZnO-sheathed TiO2 nanowires as photoanodes for performance enhanced dye-sensitized solar cells

Surface engineered angstrom thick ZnO-sheathed TiO2 nanowires as photoanodes for performance enhanced dye-sensitized solar cells

ZnO−Al2O3 and ZnO−TiO2 Core−Shell Nanowire Dye-Sensitized Solar Cells

Improving the efficiency of dye-sensitized solar cells by photoanode surface modifications

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Surface engineered angstrom thick ZnO-sheathed TiO₂ nanowires as photoanodes for performance enhanced dye-sensitized solar cells

Surface engineered angstrom thick ZnO-sheathed TiO₂ nanowires as photoanodes for performance enhanced dye-sensitized solar cells

ZnO−Al₂O₃ and ZnO−TiO₂ Core−Shell Nanowire Dye-Sensitized Solar Cells