Correlation between microstructure and property of electroless deposited Pt counter electrodes on plastic substrate for dye-sensitized solar cells

Flexible Pt counter electrodes (CEs) were prepared on indium-doped tin oxide coated polyethylene naphthalate (ITO-PEN) substrate by electroless deposition. The correlation between the microstructure and the property of the Pt CEs was investigated. Results showed that isolated Pt nanoparticles were uniformly distributed on the ITO surface at a short deposition duration, and then grew with the deposition duration, leading to the interconnection of adjacent Pt nanoparticles. The interconnection of Pt nanoparticles was beneficial to the electrical property of the Pt CEs, while it was unfavorable to the electrocatalytic property of the Pt CEs. A microstructure model was proposed to explain the correlation between the microstructure and the property of the Pt CEs. In addition, the Pt CEs showed low charge transfer resistance (1.66-0.58 Ω cm²), which was comparable to that (1.16 Ω cm²) of the conventional sputtered Pt CE. The high electrocatalytic property of the electroless deposited Pt CEs makes the assembled DSCs present comparable energy conversion efficiency of the DSCs using sputtered Pt CE.     

Ultrasonic irradiation preparation of graphitic-C3N4/polyaniline nanocomposites as counter electrodes for dye-sensitized solar cells

In this research, polyaniline/graphitic carbon nitride (PANI/g-C₃N₄) nanocomposites were synthesized via in-situ electrochemical polymerization of aniline monomer whit different number of cyclic voltammetry scans (10, 20 and 30 cycles) after electrode surface pre-preparation using a potential shock under ultrasonic irradiation. PANI/g-C₃N₄ nanocomposites with two values of g-C₃N₄ (0.010 wt% and 0.015 wt%) were deposited on the surface of the transparent conducting film (FTO glass) by immersing FTO into the aniline solution and g-C₃N₄ during the electro-polymerization. The resulting PANI/g-C₃N₄ films were characterized by Fourier transformed infra-red (FTIR), power X-ray diffraction (PXRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) techniques. The prepared electrodes were applied as counter electrode in dye-sensitized solar cells. Among them, the prepared electrode with 10 cycles and 0.01 wt% g-C₃N₄ showed the best efficiency. These hybrids show good catalytic activity in elevating tri-iodide reduction and due to the synergistic effect of PANI and g-C₃N₄, PANI/g-C₃N₄ nanocomposite electrode shows power conversion efficiency about 1.8%.     

Ni3S2@MWCNTs films for effective counter electrodes of dye-sensitized solar cells

Composite films nickel sulfide (Ni₃S₂) nanoparticles were grown on multiwall carbon nanotubes (MWCNTs) and in situ coated onto conducting glass substrates by the hydrothermal process at 170 °C. These Ni₃S₂@MWCNTs films were applied for counter electrodes (CEs) of dye-sensitized solar cells (DSSCs). In this work, nanostructure, crystalline structure, electrochemical activities and electron-charge transfer resistance of CEs were studied. In addition, the effective surface areas of CEs were analyzed and discussed as well. The power conversion efficiency (PCE) enhancement of up to 7.48%, compared with that of Ni₃S₂-DSSC, was demonstrated for a Ni₃S₂@MWCNTs DSSC.     

Electron transport in dye-sensitized solar cells based on TiO2 nanowires

Anatase titanium dioxide nanowire arrays were prepared by hydrothermally oxidizing titanium foils in aqueous alkali and transferred onto fluorinated tin oxide(FTO)glass for use as the photoanodes of front side illuminated dye-sensitized solar cells(DSCs).Electrochemical impedance spectroscopy(EIS)measurement was applied to compare the electron transport and recombination properties of DSCs using TiO2nanowire films and TiO2nanoparticle films as photoanodes.It was found that the nanowire array films possess smaller electron transport resistance(Rt)and larger electron diffusion length(Le)in the photoanodes,suggesting that the nanowire arrays can enhance the electron transport rate and have a potential to improve the charge collection efficiency of DSCs.     

Prickly polyaniline nano/microstructures as the efficient counter electrode materials for dye-sensitized solar cells

Two kinds of prickly polyaniline samples, prickly polyaniline nanorods and microgranules, are prepared through the chemically oxidative polymerization method by regulating the concentration of aniline. Scanning electron microscopy images indicate that the diameter of prickly polyaniline nanorods (PPNRs) is about 80 nm and the size of prickly polyaniline microgranules (PPMGs) is about 400 nm. The as-prepared prickly polyaniline samples are subsequently explored as the Pt-free counter electrode materials for dye-sensitized solar cells (DSCs). Electrochemical impedance spectroscopy and cyclic voltammetry measurements demonstrate that PPNR electrode displays superior electrocatalytic activity for the I₃ ^? reduction reaction to PPMG electrode, which can be attributed to the unique prickly nanorod structure that provides abundant electrocatalytic active sites and the fast charge transport pathway simultaneously. As a consequence, the DSC fabricated with PPNR counter electrode achieves a high conversion efficiency of 6.86% under illumination of 100 mW cm^?2, which is close to the efficiency of a Pt electrode-based device. This work presents a promising way to develop Pt-free and high-efficiency counter electrode in DSCs.     

Graphene/carbon nanotubes composites as a counter electrode for dye-sensitized solar cells

As an alternative platinum counter electrode in dye-sensitized solar cells (DSSCs), carbon materials based counter electrode were prepared using multi-walled carbon nanotubes (MWNTs)/graphene nano-sheets (GNS) composite by simple doctor blade method. We found that the photovoltaic performance was strongly influenced by the concentration of GNS in composite electrode. The composite electrode with 60% MWNTs and 40% GNS based DSSCs showed the maximum power conversion efficiency of 4.0% while sputter deposited platinum counter electrode based DSSCs showed a power conversion efficiency of 5.0%.     

Performance characteristics of dye-sensitized solar cells with counter electrode based on NiP-plated glass and titanium plate

The counter electrodes based on NiP-plated glass and titanium plate were prepared. The performance characteristics of the dye-sensitized solar cells with platinized NiP-plated glass electrode (Pt/NiP electrode) and platinized titanium plate electrode (Pt/TP electrode) were discussed. Pt/NiP electrode and Pt/TP electrode showed the same catalytic activity for triiodide reduction compared with platinized fluorine-doped tin oxide conducting glass electrode (Pt/FTO electrode). However, Pt/NiP electrode and Pt/TP electrode have the advantage over Pt/FTO electrode in reducing the sheet resistance and increasing light reflectivity, which resulted in improving the photovoltaic performance of dye-sensitized solar cells effectively. Compared with the cell using Pt/FTO electrode, the incident photon conversion efficiency of dye-sensitized solar cells with Pt/NiP electrode and Pt/TP electrode was increased by 20% and 5%, respectively, the overall energy efficiency of dye-sensitized solar cells with Pt/NiP electrode and Pt/TP electrode was increased by 32% and 27%, respectively.     

Very thin,highly‐conductive ZnO:Al front electrode on textured glass as substrate for thin‐film silicon solar cells

A very thin (250 nm), highly conductive (annealed), non‐texturized DC‐sputtered aluminum‐doped zinc oxide layer (ZnO:Al) deposited on a textured glass is used as substrate for thin‐film silicon solar cells. Compared to the classical approach, where wet‐chemically texturized ZnO:Al on planar glass is used, this approach allows a reduction in the as‐deposited ZnO:Al thickness of almost 70% while at the same time, thanks to the good light trapping capability of the glass texture the efficiency of the cells was maintained at the high level of 10.9%.

     

Hydrothermal synthesis of TiO2 nanocrystals in different basic pHs and their applications in dye sensitized solar cells

In this research TiO₂ nanocrystals with sizes about 11–70 nm were grown by hydrothermal method. The process was performed in basic autoclaving pH in the range of 8.0–12.0. The synthesized anatase phase TiO₂ nanocrystals were then applied in the phtoanode of the dye sensitized solar cells. It was shown that the final average size of the nanocrystals was larger when the growth was carried out in higher autoclaving pHs. The photoanodes made of TiO₂ nanocrystals prepared in the pHs of 8.0 and 9.0 represented low amounts of dye adsorption and light scattering. The performance of the corresponding dye sensitized solar cells was also not acceptable. Nevertheless, the energy conversion efficiency was better for the state of pH of 9.0. For the photoanodes made of TiO₂ nanocrystals prepared at autoclaving pH of 10.0, the dye adsorption and light scattering were quite higher. The photovoltaic characteristics of the best cell in this state were 15.25 mA/cm², 740 mV, 0.6 and 6.8% for the short-circuit current density, open-circuit voltage, fill factor and efficiency, respectively. The photoanodes composed of TiO₂ nanocrystals prepared in autoclaving pHs of 11.0 and 12.0 demonstrated lower amount of dye adsorption and higher light scattering. This was quite considerable for the state of pH of 12.0. The energy conversion efficiencies were consequently decreased compared to that of the pH of 10.0. The optimum situation was finally discussed based on the nanocrystals size and its influence on the sensitization and light harvesting efficiency.     

ZnO nanorods on undoped and indium-doped ZnO thin films as a TCO layer on nonconductive glass for dye-sensitized solar cells

We present the growth of ZnO nanostructures on indium-doped ZnO film on a non-conductive glass substrate. The indium-doped ZnO film was used as the transparent conductive layer replaces the ITO layer. Various indium doping concentrations can change the electrical properties of ZnO film. The reduced electrical resistivity was investigated from 16.60 × 10⁻² to 10 × 10⁻² Ω cm. after doping with the optimal concentration of 2 wt% indium. It is found that the characteristic of ZnO nanostructures was strongly affected with indium doping concentration in ZnO films. The overall structural characteristics of ZnO ranged from 100–500 nm in size and 7–10 μm in length and the branch-like structures can be revealed from the 2 wt% indium-doped ZnO film. The room-temperature photoluminescence spectra show a sharp ultraviolet band of 353 nm, indicated to the ZnO nanorods structure. The branch-like structures on the 2 wt% indium-doped film can be yielded the photovoltaic properties with a short-circuit current density of 3.96 mA/cm², an open-circuit voltage of 0.72 V, a fill factor of 20% and an overall power conversion efficiency of 0.56% under irradiance of 100 mW/cm² (AM 1.5 G).     

Low platinum loading PtNPs/graphene composite catalyst with high electrocatalytic activity for dye-sensitized solar cells

Platinum nanoparticles(PtNPs)/graphene composite materials are synthesized by a controlled chemical reduction of H2PtCl6 on graphene sheets.The electrocatalytic activity of a PtNPs/graphene composite counter electrode for a dye-sensitized solar cell(DSSC) is investigated.The results demonstrate that the PtNPs/graphene composite has high electrocatalytic activity for the dye-sensitized solar cell.The cell employing PtNPs(1.6 wt%)/graphene counter electrode reaches an conversion efficiency(η)of 3.89% upon the excitation of 100 mW/cm2 AM 1.5 white light,which is comparable to that of the cell with a Pt-film counter electrode(η=3.76%).It suggests that one can use only 14% Pt content of the conventional Pt-film counter electrode to obtain a comparable conversion efficiency.It may be possible to obtain a high performance DSSC using the PtNPs/graphene composite with a very low Pt content as a counter electrode due to its simplicity,low cost,and large scalability.     

Facile synthesis of nitrogen-doped reduced graphene oxide as an efficient counter electrode for dye-sensitized solar cells

A nitrogen-doped reduced graphene oxide (N-RGO) nanosheet was synthesized by a simple hydrothermal method and characterized by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning electrode microscopy. After being deposited as counter electrode film for dye-sensitized solar cells (DSSCs), it is found that the synthesized N-RGO nanosheet has smaller charge-transfer resistance and better electrocatalytic activity towards reduction of triiodide than the reduced graphene oxide (RGO) nanosheet. Consequently, the DSSCs based on the N-RGO counter electrode achieve an energy conversion efficiency of 4.26%, which is higher than that of the RGO counter electrode (2.85%) prepared under the same conditions, and comparable to the value (5.21%) obtained with the Pt counter electrode as a reference. This N-RGO counter electrode offers the advantages of not only saving the cost of Pt itself but also simplifying the process of counter electrode preparation. Therefore, an inexpensive N-RGO nanosheet is a promising counter electrode material to replace noble metal Pt.

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Graphical abstract A nitrogen-doped reduced graphene oxide nanosheet was synthesized by a simple hydrothermal method, which is a promising counter electrode material to replace noble metal Pt.

     

纳米TiO2叶片状阵列电极的制备及其在染料敏化太阳电池中电子的输运性能

在低温条件下采用定向刻蚀技术, 对金属Ti片表面用H₂O₂溶液进行刻蚀氧化, 制备了垂直生长的纳米TiO₂叶片状阵列薄膜电极. 通过X射线衍射分析表明, 纳米TiO₂叶片状阵列薄膜经500 ℃下烧结1 h后, 从无定型转变为锐钛矿相. 场发射扫描电子显微镜观察表明: 在80 ℃下的H₂O₂溶液刻蚀氧化, 经1 d制备得到的是Ti片表面垂直生长的叶片状阵列, 其形貌均匀且完整地 关键词： 2')" href="#">纳米TiO₂ 叶片状阵列电极 染料敏化太阳电池 电子传输     

Low resistance dye-sensitized solar cells based on all-titanium substrates using wires and sheets

Low resistance dye-sensitized solar cells (DSSCs) based on all-titanium substrates were proposed in this paper. To minimize the internal resistance of DSSCs, the titanium wires and titanium sheets were used as the substrates of the photoanode and the counter electrode, respectively. Compared with the FTO substrate, titanium wires could absorb much diffused light by back reflection since the reflectivity in the titanium sheet was highly increased up to 53.12%. Furthermore, the transmittance of the front cover was increased by 13.2% using the super white glass instead of FTO substrate. The thickness of TiO₂ thin film coated on titanium wire was optimized to achieve a high cell performance. The efficiency of 5.6% for the cell was obtained with a J_sc of 15.41 mA cm⁻², V_oc of 0.59 V, and FF of 0.62. The results showed that the titanium-based DSSCs had superiority for producing the large-scale DSSCs without metal grid line.     

Controlled synthesis of TiO2-B nanowires and nanoparticles for dye-sensitized solar cells

Controllable synthesis of the TiO₂-B nanowires (NWs) and nanoparticles (NPs) had been achieved via a facile hydrothermal route, respectively, only by tuning the solution volume. The dye-sensitized solar cells prototypes had been fabricated using TiO₂-B NW and NP electrodes, respectively. The TiO₂-B NP cells had higher photocurrent and photoelectrical conversion efficiency than the TiO₂-B NW cells though the latter exhibited larger photovoltage compared to the former. The key factors such as the photogenerated electron injection drive force, surface defects and the interfacial charge transfer, which determined the photoelectrical properties, had been systematically researched with the surface photovoltage spectra (SPS) and the electrochemical impedance spectra (EIS). The SPS proved that there was larger photoelectron injection drive force in TiO₂-B NP photoelectrode than that in NW photoelectrode. And the electrochemical impedance spectra (EIS) revealed that TiO₂-B NP cells had faster interface charge transfer compared to TiO₂-B NW cells. Both proved that NP cells had the higher photocurrents.     

锐钛矿相TiO2纳米管的制备及其染料敏化太阳电池

以商用金红石相TiO₂粉末为原料,通过在碱性溶液中150℃水热48h的方法合成TiO₂纳米管.采用SEM,TEM,XRD分析手段对TiO₂纳米管的形貌和结构演变进行了表征.制成的TiO₂纳米管与TritonX-100,乙酰丙酮混合后,通过丝网印刷的方法涂敷到ITO导电玻璃衬底上,并且在450℃下烧结30min后得到可应用于染料敏化太阳电池的多孔光阳极.将此光阳极浸泡于N719染料敏化后,与镀铂对电极组装电池,两者之间灌 关键词： 2纳米管')" href="#">TiO₂纳米管 染料敏化太阳电池 水热法     

Application of Pt sputter-deposited counter electrodes based on micro-patterned ITO glass to quasi-solid state dye-sensitized solar cells

The effects of the Pt catalyst sputter deposited on the patterned ITO glass (SD-Pt/pITO) on the photovoltaic properties and charge-transfer characteristics at the Pt/electrolyte interface of dye-sensitized solar cells (DSSCs) are studied and compared with those of a conventional Pt counter electrode deposited by thermal reduction on fluorine-doped tin oxide (FTO) glass (TD-Pt/FTO). The DSSC with the SD-Pt/pITO (sample cell) shows a lower charge-transfer resistance than that of the DSSC with the TD-Pt/FTO (reference cell), which leads to an improvement of its fill factor by about 7.6%. The long-term durability test performed for 1000 h at room temperature reveals that the sample cell retains up to 99% of its energy conversion efficiency, while that of the reference cell is degraded by about 7.2%.     

ZnO/Ag/ZnO multilayer transparent electrode for highly-efficient ITO-Free polymer solar cells

Ultrathin metal film (UTMF) with a ZnO/Ag/ZnO hybrid structure was used as transparent electrode in a high-efficiency bulk heterojunction system for the fabrication of ITO-free polymer solar cells. The performance of the devices was carefully tuned through optical simulation using transfer matrix method by varying the thickness of ZnO seed layer and thin absorber layer. By employing appropriate device architecture, polymer solar cells fabricated using this UTMF-based electrode show efficiency as high as 9.49%, which is slightly higher compared to that of ITO-based device. From good agreement between the external quantum efficiency and optical modeling, it was found that the optimized microcavity configuration formed in UTMF-based device can greatly enhance the absorbance of the BHJ layer at longer wavelength as well as the favored exciton distribution for better charge transport and collection.