P25 Photoanode Research Articles

Contribution of bamboo charcoal interconnection in double electrodes to evaluate the photovoltaic performance

Bamboo charcoal (BC)-doped titanium dioxide (P25/BC) and modified BC (MBC) loaded with Fe3O4 (MBCF) were used as double electrodes to improve the power conversion efficiency (PCE) of a dye-sensitized solar cell (DSCC). BC was doped into the P25 photoanode, and P25 improved dye adsorption and reduced the transfer impedance of photogenerated electrons. The PCE of P25-Pt (4.96%) was 6.27% higher than that of P25/BC-Pt. MBC contained more structural defects, and the oxygen-containing reactive groups generated on its surface combined with Fe3+ ions, resulting in a uniform loading of Fe3O4 on MBC. The high electrocatalytic performance of Fe3O4 with the abundant structural defects of MBC reduced the charge transfer resistance and provided fast electron transfer paths, giving MBCF good electrical conductivity and electrocatalytic activity. DSSCs assembled using the P25/BC photoanodes and MBCF-2 CE showed a PCE of 4.27%. Electrochemical performance tests of MBCF-2 showed a specific capacitance of 150 F/g at 1 A/g and capacitance retention of 91.1% after 5000 cycles. The results demonstrate that BC has potential electrocatalytic and energy storage applications, and this paper provides a feasible strategy for applying biomass carbon-based materials in DSSCs.

Fabrication and performance analysis of set standard natural dye-sensitized solar cell (N-DSSC) using extracted Terminalia kattapa (Red), Azadirachia indica (Green), and Clitoria ternatea (Blue) dyes with virgin Degussa p25 photo-anode

Fabrication and performance analysis of set standard natural dye-sensitized solar cell (N-DSSC) using extracted Terminalia kattapa (Red), Azadirachia indica (Green), and Clitoria ternatea (Blue) dyes with virgin Degussa p25 photo-anode

A synergistic effect of NaYF4:Yb,Er@NaGdF4:Nd@SiO2 upconversion nanoparticles and TiO2 hollow spheres to enhance photovoltaic performance of dye-sensitized solar cells

Introducing upconversion nanoparticles (UCNPs) or fabricating TiO2 hollow spheres (TiO2-HSs) are considered two feasible strategies to enhance the photovoltaic performance of dye-sensitized solar cells (DSSCs). However, studies investigating a combination of UCNPs and TiO2-HSs for the application in DSSCs are still scarce. In this contribution, NaYF4:Yb,Er@NaGdF4:Nd@SiO2 UCNPs and TiO2-HSs were synthesized and respectively applied as upconversion layers and scattering layers on the TiO2 photoanode of DSSCs. The influence of different doping ratios of UCNPs on cell performance was explored. The present results reveal that the DSSCs device based on conventional P25 photoanode films incorporating the UCNPs with 10% can achieve a photovoltaic efficiency of 6.65%, showing 29.63% enhancement in comparison to the device without UCNPs. When the TiO2-HSs are used as scattering layers above the P25 film, the DSSCs device obtains a higher photovoltaic efficiency of 6.97%. More importantly, combining the UCNPs and TiO2-HSs can further enhance the photoelectrical property of DSSCs, realizing an optimal efficiency of 8.17%. Such an improvement can be attributed to a synergistic mechanism arising from the upconversion effect of UCNPs and the light scattering effect of TiO2-HSs. This work opens a new way of preparing composite photoanode films to improve the photovoltaic performances of DSSCs.

The TiO2 films with sandwich-type polyoxometalates in dye sensitized solar cells with electron recombination decreasing and dye adsorption increasing

Unfavorable electron recombination, which hinders the efficiency of dye-sensitized solar cells (DSSCs), usually occurs at the TiO2/dye/electrolyte interface on a photoanode. Polyoxometalates (POMs), as good electron acceptors, can be used as electron-transfer materials in DSSCs to improve electron transport in TiO2 and reduce electron recombining on the interface of a photoanode. In this paper, the pure inorganic sandwich-type POM Na9[Na3(H2O)6Cu3(H2O)3(SbW9O33)2]·40H2O (Cu3Na3POM) was mixed with TiO2 to form nanocomposites by simple sol-gel method. X-ray photoelectron spectroscopy (XPS) proved that Cu3Na3POM and TiO2 combined. Then the nanocomposite was doped with P25 to form Cu3Na3POM@TiO2/P25 photoanodes which were applied to the DSSCs. The Cu3Na3POM improved the transfer and recombination of electrons in the photoanode, proved by open circuit voltage decay (OCVD) and electrochemical impedance spectroscopy (EIS). Scanning electron microscopy (SEM) and ultraviolet-visible (UV-vis) absorption spectra showed that Cu3Na3POM optimized the morphology of the photoanode and the adsorption capacity of dye. The electrochemical test showed that the photoelectric conversion efficiency of DSSCs with Cu3Na3POM@TiO2/P25 photoanodes was enhanced to 6.91%, which was 13.66% higher than the DSSCs without Cu3Na3POM.

Enhanced Performance of Dye-Sensitized Solar Cells Via the Synergic Effect of Hierarchical TiO2 Networks and Au Nanoparticle Decoration

The construction of favorable photoanode configurations is of great importance to enhance the performance of dye-sensitized solar cells (DSSCs). In this work, a double-layer photoanode architecture consisting of a top layer of hierarchical TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> networks (HTNs) and a bottom layer of commercial P25 nanoparticles (NPs) was designed and prepared by a facile one-step hydrothermal method. This unique double-layer structure not only affords stronger light scattering and faster electron transport relative to the single-layer P25 photoanode, but also ensures more close contact between different functional layers in contrast to commonly used multistep mechanical coated photoanodes. Furthermore, Au NPs with particle sizes of around 20 nm were incorporated to decorate the HTN photoanode. The localized surface plasmon resonance effect of such Au NPs significantly enhances the light absorption of N719 dye molecules. Benefitted from the splendid light harvesting and superior electron collection, the Au-HTN photoanode configuration delivers an enhanced power conversion efficiency of 5.97%, yielding ~19% improvement compared to the device based on the conventional P25 photoanode. This work highlights the design of photoanodes with unique nanostructures for enhancing the photovoltaic performance of DSSCs.

Mesoporous TiO2 hollow microsphere constructed with TiO2 nanospheres: high light scattering ability and enhanced photovoltaic performance for dye-sensitized solar cells

Mesoporous TiO2 hollow microspheres (HTM) composed of irregularly arranged nanospheres were prepared through a one-pot template-free solvothermal way based on the aldol condensation reaction of acetylacetone. The synthesized hollow TiO2 microspheres were investigated by a series of characterizations. Images of FE-SEM and TEM demonstrate that the surface of TiO2 hollow microsphere with a diameter of 1.5 µm are mesoporous and constructed with 150 nm TiO2 nanospheres. The mesoporous shell of the hollow microspheres is about 110 nm in thickness. XRD pattern shows the prepared samples are anatase phase. UV–Vis spectrum indicates that excellent light scattering ability of the prepared sample. The DSSCs using mesoporous TiO2 hollow microspheres as the top scattering layer exhibits the improvement of short-circuit current density (Jsc) and conversion efficiency (η) of 6.63%, while the benchmarked P25 photoanode is only 5.09%, showing 30% increase in the energy conversion efficiency.

Growth of Sb2S3 semiconductor thin film on different morphologies of TiO2 nanostructures

Sb2S3 is a promising sensitizer material for solar cell devices. Growth and morphological characteristics of Sb2S3 nanoparticles made by chemical bath deposition on anatase TiO2 with various morphological attributes including mesoporous P25 nanoparticles, microsphere and its composite, anodized nanotubes, and nanorods are shown to widely differ. Sb2S3 coated on P25 photoanode for different time duration (45 min to 4 h) show that the deposition for 2 h is sufficient to obtain uniform coating with good crystallinity. Sb2S3 growth on TiO2 nanotube, nanorod and microspheres lead to conformal coverage, whereas, it hardly grows on glass/FTO. Photoconversion ability is studied using photoconductivity and photovoltaic measurements. Optimally sensitized Sb2S3 solar cells fabricated using I−/I3− liquid electrolyte exhibit photoconversion efficiency up to 0.35 % for cell area of 0.25 cm2. High photoconductivity found in Sb2S3 sensitized TiO2 microsphere-composite and nanorod compared to the P25-TiO2 photoanode is attributed to good connectivity between particles and effective electron transport.

The Synchronization of Electron Enricher and Electron Extractor as Ternary Composite Photoanode for Enhancement of DSSC Performance

This work developed a novel ternary composite photoanode of dye-sensitized solar cell (DSSC) composed of (i) N-, S-doped titanium dioxide with exposed {001} facet (N-, S-TiO2{001}), (ii) N-, S-doped reduced graphene oxide (N-, S-rGO), and (iii) commercial titanium dioxide (P25). The DSSC device fabricated with the ternary composite photoanode showed the greatest of power conversion efficiency (8.62%) compared to the device fabricated with P25 photoanode (3.20%). This enhancement was attributed to the synergistic effect of the N-, S-TiO2{001} and the N-, S-rGO, which act as an electron enricher and an electron extractor, respectively.

TiO2 hierarchical nanowire-P25 particulate composite photoanodes in combination with N-doped mesoporous carbon/Ti counter electrodes for high performance quantum dot-sensitized solar cells

The time-consuming transport of photo-generated electrons across conventional photoanode film, composed of disordered P25 TiO2 nanoparticulates, is one of the main bottlenecks to improve the performance of quantum dot-sensitized solar cells (QDSCs). A convenient and effective method was developed for the preparation of high performance photoanodes based on composite paste composed of conventional P25 TiO2 nanoparticulates and TiO2 hierarchical nanowires (HNW) for QDSCs. The shortened transport path in the composite photoanode brings forward suppressed charge recombination processes at the interfaces between photoanode and electrolyte, and improved photovoltaic performance of the resulting solar cells. Through optimizing the composite photoanode and the adoption of N-doped mesoporous carbon/Ti counter electrodes, average power conversion efficiency of Zn-Cu-In-Se (ZCISe) QDSCs was increased from 12.77% corresponding to conventional P25 photoanodes to 13.43% (Jsc = 27.38 mA cm−2, Voc = 0.764 V, and FF = 0.642) corresponding to photoanodes with HNW/P25 weight ratio of 0.1%. Furthermore, this composite photoanode is also effective in improving the photovoltaic performance of QDSCs under different QD sensitizers (such as Zn-Cu-In-S (ZCIS) QDs) as well as different counter electrodes (such as Cu2S/brass).

Anatase TiO2 nanowires with nanoscale whiskers for the improved photovoltaic performance in dye-sensitized solar cells

TiO2 as an efficient electron transfer material has been widely utilized in dye-sensitized solar cells (DSSCs), and the morphology of TiO2 plays a decisive role in the performance of DSSCs. However, one-dimensional TiO2 nanowires, which are generally used as the efficient electron transport layers, have small specific surface area and low dye loading. Here, we introduce an effective and reproducible one-step hydrothermal method to prepare TiO2 nanowire with nanoscale whiskers. The synthetic sample was characterized by the field emission scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction. TiO2 nanowire with nanoscale whiskers has a high light scattering performance and high dye loading capacity. This novel TiO2 nanowire show a power conversion efficiency (PCE) of 4.12%, which is close to the benchmark of P25 nanoparticle usually used in DSSC fabrication. The PCE of DSSC-3 using TiO2 nanowire with nanoscale whiskers and commercial P25 double-layer photoanode has a PCE of 5.98%, showing an increase of 11.98% when compared with DSSC-2 based on pure P25 photoanode.

Enhancing the photoelectric conversion efficiency of dye-sensitized solar cell using the upconversion luminescence materials Y2O3:Er3+ nanorods doped TiO2 photoanode

A new type of TiO2 photoanode containing upconversion luminescence materials Y2O3:Er3+ nanorods is developed, which is effective to enhance the photoelectric conversion efficiency of dye-sensitized solar cell. The Y2O3:Er3+ nanorods are synthesized using a hydrothermal process and the photoandodes are prepared via coating the TiO2 (P25) and Y2O3:Er3+ mixture with various Y2O3:Er3+ concentrations on the fluorine doped tin oxide (FTO) substrates. We show that the TiO2 photoanode with an Y2O3:Er3+ concentration of 4% exhibits the highest photoelectric conversion efficiency (7.80%), which is 43.6% higher than that of the pure P25 photoanode (5.43%). This great enhancement is attributed to the additional, useful photons converted from infrared (IR) photons in sun light by the doped Y2O3:Er3+ upconversion nanorods. In addition, the electrochemical impedance spectroscopy (EIS) analysis demonstrates that the doping of Y2O3:Er3+ improves the charge transfer and electron lifetime of the dye-sensitized solar cell.

Study on Surface and Crystallinity of TiO₂ Microspheres as the Photoanode of Dye-Sensitized Solar Cells.

In this study, Titanium dioxide (TiO2) microspheres were synthesized by a hydrothermal method from the same precursor: titanium sulfate. Two different TiO2 microspheres with different surface and crystallinity were fabricated by adding different additives as the photoanode of dye-sensitized solar cells (DSSCs). The growth mechanisms of the TiO2 microspheres were discussed. The effect of surface status and the crystallinity of the TiO2 microspheres on the photovoltaic characteristic of DSSCs were investigated. It was found that when the TiO2 microsphere with loose construction and rough surfaces along with better crystallinity was applied on photoanode, the DSSC exhibited better photoelectric performance than the DSSC with dense TiO2 microsphere photoanode. TiO2 microsphere with loose construction and rough surface applied to photoanode, the DSSC showed photoelectric conversion performance of 3.83% which is 53.8% higher than DSSC with dense and smooth TiO2 microsphere photoanode, and it is also superior to the DSSC with P25 photoanode.

Anatase TiO2 nanocrystals via dihydroxy bis (ammonium lactato) titanium (IV) acidic hydrolysis and its performance in dye-sensitized solar cells

The conventional way to synthesize anatase TiO2 with dihydroxy bis (ammonium lactato) titanium (IV) (TALH) is adjusting pH value of precursor solution to basic condition. In this paper, we prepared white color anatase TiO2 under acid condition via a hydrothermal route. TEM image shows the TiO2 has a sharp contour and crystallite size is about 5–10 nm. The TiO2 also has specific surface area of 97 m2/g and its average pore diameter is about 8.5 nm after sintering at 500 °C for 30 min. These characters make it to be a proper candidate for DSSCs’ photoanode. By comparing the DSSCs’ performance between the TiO2 we have synthesized (A35) and P25, A35 has energy conversion efficiency of 6.92% without any scattering layers, which was 17.9% higher than P25 photoanode. The higher specific area and good pore diameter distribution of A35 make photoanode absorb more dye molecules. The IPCE curve and dye absorbing experiment further confirmed the above mentioned results. DSSCs’ analysis revealed the white color anatase TiO2 could be achieved under acid condition when using TALH precursor.

Facile synthesis of chrysanthemum flowers-like TiO2 hierarchical microstructures assembled by nanotube for high performance dye-sensitized solar cells

Abstract Chrysanthemum flowers-like TiO2 hierarchical microstructures assembled by nanotube are synthesized by a two-step hydrothermal route. The final TiO2 hierarchical microstructures are applied as a scattering layer on top of a transparent nanocrystalline TiO2 film, serving as the photoelectrode of dye-sensitized solar cells (DSSCs). In addition to efficient light scattering, the hierarchical microstructures provide a large surface area (105.4 m2/g) for higher dye loading and nanotube primary structure also provide a straight path for the electron fast transport. This multi functioning suggests that chrysanthemum flowers-like TiO2 hierarchical microstructures may be good scatter materials in DSSCs. A high efficiency of 7.71% is achieved for using the as-synthesized hierarchical microstructures as scattering layer, which is 21.8% higher than that of commercial P25 photoanode (6.33%) with the similar thickness.

An insight into titania nanopowders modifying with manganese ions: A promising route for highly efficient and stable photoelectrochemical solar cells

Abstract In this study, we firstly report the synthesis of pure and manganese (Mn) doped titania nanopowders by solution-based chemical process followed by ball-milling and ultra-sonication processes and their usage as photoanode material in dye-sensitized solar cells (DSSCs). Besides examining the properties of physical and charge transfer dynamics, we also made a detailed cost analysis to compare with commercial P25 nanopowders. By incorporating Mn 4+ ions into titania matrix, we have also succeeded not only in lower price but also in significantly enhancing the dye loading capability by increasing specific surface area and the retarding the recombination of electron-hole pairs by forming the discrete interstitial states within the band gap as well as accelerating electron transfer by tailoring in energy gap, leading to better photovoltaic performance. Such that, the cell assembled with 0.4 mol% Mn doped TiO 2 yields an efficiency of 7.33%, which is ∼17% and ∼65% higher than the value obtained for P25 and pure titania-based photoanode, respectively, and shows a fast, stable, and completely reversible photocurrent response accompanying each switch-on/off event. Furthermore, the photoinduced electron transfer (PET) measurements indicate an efficient interfacial charge transfer for 0.4 mol%Mn doped titania (k ET = 0.99 × 10 8 s –1 ) compared to the both synthesized pure TiO 2 (0.74 × 10 8 s –1 ) and commercial P25 (0.94 × 10 8 s –1 ) photoanodes. This work renders the possibility of synthesizing low-cost and easy-preparation Mn-doped titania nanopowders and describes an innovative approach to further boost the efficiency of green technologies such as solar-driven water splitting, photoelectrochemical and perovskite solar cells applications.

Yb,Er-doped CeO2 nanotubes as an assistant layer for photoconversion-enhanced dye-sensitized solar cells

Abstract Yb,Er-doped CeO 2 nanotubes were successfully synthesized using Ag nanowires as a hard template via a facile hydrothermal reaction and subsequent calcination and leaching processes. Yb,Er-doped CeO 2 nanotubes as a promising assistant layer were investigated to determine theirs photovoltaic properties in an effort to enhance the power conversion efficiency of dye-sensitized solar cells (DSSCs). The influence factors of photoelectric properties of CeO 2 :Yb,Er NTs, including diameter of nanotubes, hydrothermal time, calcination temperature, and elements doping, have been studied. Compared with pristine P25 photoanode, the DSSCs fabricated by CeO 2 :Yb,Er nanotubes and P25 exhibited a power conversion efficiency ( η ) of 8.67%, an increase of 34%, and incident photo-to-electric conversion efficiency (IPCE) of 92.96%, an increase of 48.83%, which evidence that CeO 2 :Yb,Er NTs are a promising assistant photoanode material for DSSCs. The enhance mechanism of CeO 2 :Yb,Er nanotubes has been further revealed according to experimental results.

Microsphere Assembly of TiO2 Rectangular Nanotubes: Facile Fabrication and Photovoltaic Property

Novel hierarchical microspheres constructed with TiO2 rectangular nanotubes (TRTMs) were fabricated via a facile route. The obtained samples were investigated by the field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The FESEM results showed that the solid cuboids precursor become rectangular and hollow TiO2 nanotube after calcination at 500°C for 3h. The XRD spectra and TEM results confirmed that crystalline anatase TiO2 was formed. Meanwhile, a possible mechanism for the formation of the hollow structure was also briefly proposed. The prepared TRTMs were applied as the scattering layer on the top of Deguss P25 nanoparticles thin film and were then used as the photoanode of dye-sensitized solar cell (DSSCs). This prepared photoanode had enhanced light harvesting capabilities due to the ability to reflect the transmission light into the P25 sub-layer, which ultimately led to an increase in the electron density. The EIS spectra showed that the optimized photoanode using TRTMs as the scattering layer is benificial for electron transport due to the synergistic effect of the excellent light-scattering ability of TRTMs and the relatively high dye adsorption amount of P25 sublayer. An overall conversion efficiency of 7.34% was obtained for the optimized bi-layer photoanode, and a 40.9% increment in conversion efficiency was achieved even though the dye adsorption is 45.8% lower than that of pure P25 photoanode.

Mesoporous TiO2 microspheres synthesized via a facile hydrothermal method for dye sensitized solar cell applications

Mesoporous TiO2 microspheres were successfully synthesized by a facile hydrothermal process and the obtained product was sintered at 450 °C. The sintered TiO2 powder was characterised by powder X-ray diffraction pattern and the result shows pure anatase phase with good crystalline nature. The morphological image of field emission scanning electron microscopy and high resolution transmission electron microscopy shows spherical shape and size of the particles is around 100 to 300 nm. The Brunauer–Emmett–Teller surface area of synthesized TiO2 material was 56.32 m2 g−1 and average pore width of synthesized materials was 7.1 and 9.3 nm. Bimodal pore structure of TiO2 microspheres has been very effective for electrolyte diffusion into photoanode in dye sensitized solar cells. The synthesized anatase TiO2 microsphere based dye sensitized solar cells have high surface area with light scattering effect to enhance the photocurrent and conversion efficiency than the commercial P25 photoanode material. The power conversion efficiency of synthesized mesoporous TiO2 microspheres and commercial P25 material is 4.2 and 2.7 % respectively. Therefore bimodal mesoporous anatase TiO2 microsphere appears to be a promising and potential candidate for dye sensitized solar cells (DSSC) application.

TiO2 nanoparticles embedded in hollow cube with highly exposed {001} facets: Facile synthesis and photovoltaic applications

A hollow anatase titania (HAT) composed of irregularly arranged micro-cube with highly exposed {001} facets was obtained by sintering a TiOF2 solid precursor at 773 K, which was prepared using one-steep hydrothermal reaction of titanium precursor under the mediation of HF and HAc. The synthesized samples were investigated by X-ray powder diffraction (XRD), field emission-scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM). FE-SEM and TEM images indicate that the TiO2 hollow structures with a diameter of 1–2 μm are assembled by cube-like subunits with flat and smooth surfaces. The exposed surface with a thickness of about 100 nm of the TiO2 micro-cube is {001} facet. Inside the micro-cube, some TiO2 particles exist. XRD pattern shows the as-prepared samples are anatase phase. A possible temperature-induced solid-phase oriented rearrangement process is proposed to understand the formation mechanism of the hollow anatase TiO2 structure from the TiOF2 precursor. UV–Vis spectrum demonstrates that the as-prepared samples have high light scattering ability, which is important for the good performance of dye-sensitized solar cells. When used in dye-sensitized solar cells, the device employing the photoanode with two layers of HAT as top scattering layer demonstrates improved short-circuit current density (Jsc) therefore higher energy conversion efficiency (η) of 6.39% in comparison to 4.84% from the cell with P25 photoanode.

Dual Functional TiO2-Au Nanocomposite Material for Solid-State Dye-Sensitized Solar Cells.

Titanium dioxide-gold nanocomposite ((TiO2-Au)(nps)) materials dispersed in poly(diallyldimethylammonium chloride) (PDDA) polymer electrolyte are employed as solid-state electrolytes in a dye-sensitized solar cell (DSSC) containing nanocrystalline TiO2 nanoparticle (P25) or (P25-Au)(nps) thin film photoanode adsorbed with a near-IR dye sensitizer, nickel-phthalocyanine (NiPcTs). The photocurrent-photovoltage characteristics of the DSSCs are evaluated under standard AM 1.5 G simulated solar irradiation of 100 mW/cm2. The (TiO2-Au)(nps) nanocomposite material incorporated into the PDDA polymer electrolyte promotes interfacial charge transfer process, reduces crystallinity of the polymer electrolyte and enhances mobility of the /-/I3- redox couple, which are resulted in -6-fold increase in the overall solar to electrical energy conversion efficiency when compared to the unmodified polymer electrolyte based DSSC. When the P25 photoanode is replaced with the (P25-Au)(nps) photoanode, a further 8-fold increase in the overall energy conversion efficiency is achieved, owing to the increas in the charge transport through the photoanode. The photovoltaic performance of the present DSSC configuration is also compared with that of a cell sensitized by using standard N719 dye.