Non-precious transition metal-based counter electrodes for dye-sensitized solar cells

Journal of Solid State Electrochemistry - A non-platinum metal catalyst, TiNx-C, was synthesized through the high-pressure pyrolysis method, which was characterized using a transmission electron...     

High-performance Pt-NiO nanosheet-based counter electrodes for dye-sensitized solar cells

High-performance counter electrodes for dye-sensitized solar cells (DSSCs) are fabricated with platinum-nickel oxide (Pt-NiO) nanosheets as catalytic materials. Firstly, the Pt-Ni nanosheets are synthesized via galvanic replacement reaction between pre-synthesized Ni nanosheets and an aqueous H₂PtCl₆ solution. Secondly, after thermal treatment in air, the Pt-Ni alloys are turned to Pt-NiO nanosheets. The related data of cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel polarization reveal that Pt-NiO counter electrodes show highly catalytic activity and low charge transfer resistance. The DSSC with Pt-NiO counter electrode exhibits power conversion efficiency (PCE) of 8.40 %, which is lower than that of the DSSC containing commercial available Pt counter electrode (9.15 %) under full sunlight illumination (100 mW cm^?2, AM1.5G). However, owing to the extremely high transparency of Pt-NiO counter electrode, when putting an Ag mirror behind the back side of the DSSC, the reflected light can bring great enhanced PCE (11.27 %).     

Economical and effective sulfide catalysts for dye-sensitized solar cells as counter electrodes

Molybdenum sulfide (MoS(2)) and tungsten sulfide (WS(2)) are proposed as counter electrode (CE) catalysts in a I(3)(-)/I(-) and T(2)/T(-) based dye-sensitized solar cells (DSCs) system. The I(3)(-)/I(-) based DSCs using MoS(2) and WS(2) CEs achieved power conversion efficiencies of 7.59% and 7.73%, respectively.     

Application of carbon materials as counter electrodes of dye-sensitized solar cells

Hard carbon spherule (HCS) has been investigated as a counter electrode for dye-sensitized solar cells. The overall conversion efficiency of the cell reached 5.7%, which is comparable to 6.5% of the counter electrode of platinum-sputtered fluorine-doped tin oxide used in Grätzel-type solar cells under the same experimental condition. It is found that the photovoltaic performance was strongly affected by the specific surface areas of the carbon materials.     

Economical Pt-free catalysts for counter electrodes of dye-sensitized solar cells

Three classes (carbides, nitrides and oxides) of nanoscaled early-transition-metal catalysts have been proposed to replace the expensive Pt catalyst as counter electrodes (CEs) in dye-sensitized solar cells (DSCs). Of these catalysts, Cr(3)C(2), CrN, VC(N), VN, TiC, TiC(N), TiN, and V(2)O(3) all showed excellent catalytic activity for the reduction of I(3)(-) to I(-) in the electrolyte. Further, VC embedded in mesoporous carbon (VC-MC) was prepared through in situ synthesis. The I(3)(-)/I(-) DSC based on the VC-MC CE reached a high power conversion efficiency (PCE) of 7.63%, comparable to the photovoltaic performance of the DSC using a Pt CE (7.50%). In addition, the carbide catalysts demonstrated catalytic activity higher than that of Pt for the regeneration of a new organic redox couple of T(2)/T(-). The T(2)/T(-) DSCs using TiC and VC-MC CEs showed PCEs of 4.96 and 5.15%, much higher than that of the DSC using a Pt CE (3.66%). This work expands the list of potential CE catalysts, which can help reduce the cost of DSCs and thereby encourage their fundamental research and commercial application.     

Platinum/carbon black composites as counter electrodes for high-performance dye-sensitized solar cells

Journal of Solid State Electrochemistry - Low-cost counter electrodes for dye-sensitized solar cells (DSSCs) are prepared using platinum/carbon black (Pt/CB) composites via a spin-coating process....     

Performance of dye-sensitized solar cells with various carbon nanotube counter electrodes

Double-wall carbon nanotubes (DWCNTs), single-wall carbon nanotubes (SWCNTs), and multi-wall carbon nanotubes (MWCNTs) were investigated as an alternative for platinum in counter-electrodes for dye-sensitized solar cells. The counter-electrodes were prepared on fluorine-doped tin oxide glass substrates by the screen printing technique from pastes of carbon nanotubes and organic binder. The solar cells were assembled from carbon nanotubes counter-electrodes and screen printed anodes made from titanium dioxide. The cells produced with DWCNTs, SWCNTs or MWCNTs have overall conversion efficiencies of 8.0%, 7.6% and 7.1%, respectively. Electrochemical impedance spectroscopy measurements revealed that DWCNTs displayed the highest catalytic activity for the reduction of tri-iodide ions. The large surface area and superior chemical stability of the DWCNTs facilitated the electron-transfer kinetics at the interface between counter-electrode and electrolyte and yielded the lowest transfer resistance, thereby improving the photovoltaic activity. A short-term stability test at moderate conditions confirmed the robustness of solar cells based on the use of DWCNTs, SWCNTs or MWCNTs.

Solvent volume-driven CuInAlS2 nanoflake counter electrode for effective electrocatalytic tri-iodide reduction in dye-sensitized solar cells

Journal of Solid State Electrochemistry - The influence of solvent volume on the properties of CuInAlS2 (CIAS) thin films deposited using simple and cost-effective nebulizer spray technique is...     

Nickel phosphide-embedded graphene as counter electrode for dye-sensitized solar cells

Nickel phosphide-embedded graphene, prepared by the hydrothermal reaction of red phosphorus, nickel chloride, and graphene oxide in a mixture of ethylene glycol-water, is investigated as the counter electrode of DSSCs. It is demonstrated that the DSSC with the nickel phosphide-embedded graphene as the new counter electrode presents an excellent performance competing with that of the Pt electrode.     

Multi-wall carbon nanotube counter electrodes for dye-sensitized solar cells prepared by electrophoretic deposition

In this study, electrophoretic deposition (EPD) was employed to fabricate multi-wall carbon nanotube (MWCNT) counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). Firstly, raw MWCNTs were functionalized by means of an acid mixture solution and then subjected to EPD. The results obtained from Raman spectroscopy, Fourier transform infrared spectroscopy, field-emission scanning electron microscope, and cyclic voltammogram demonstrated that the defects and open ends on the MWCNTs can be obtained via chemical functionalization and thus facilitate the enhancement in the electrocatalytic activity for I₃⁻ reduction of MWCNT CEs. In addition to optimizing chemical functionalization of MWCNTs surface, the optimal thickness of MWCNT CEs prepared by EPD was also investigated. Additionally, consecutive cyclic voltammetric tests demonstrated that the MWCNT CE fabricated by EPD possessed excellent electrochemical stability. In comparison with MWCNT CEs fabricated by tape-casting approach, MWCNT CEs prepared by EPD presented a superior adhesion between MWCNT deposits and conducting glass substrates. Therefore, MWCNT CEs fabricated by EPD can be of great potential for use in low-cost plastic DSSCs.     

Transparent graphene/PEDOT–PSS composite films as counter electrodes of dye-sensitized solar cells

Composite films of graphene and polystyreneslufonate doped poly(3,4-ethylenedioxythiophene) (graphene/PEDOT–PSS) were deposited on indium tin oxide (ITO) substrates by spin coating at room temperature and applied as counter electrodes of dye-sensitized solar cells (DSSCs). A 60 nm thick composite film (contained 1 wt% graphene) coated ITO electrode exhibited high transmittance (>80%) at visible wavelengths and high electrocatalytic activity. The energy conversion efficiency of the cell with this film as counter electrode reached 4.5%, which is comparable to 6.3% of the cell with platinum counter electrode under the same experimental condition.     

Copper doped manganese dioxide as counter electrode for dye-sensitized solar cells

Many materials have been tried as the counter electrode (CE) material as a substitute to the noble metal Pt in dye-sensitized solar cells (DSSCs). The CE property is critical to the operation of a DSSC as it catalyzes the reduction of I₃^- ions and retrieves the electrons from the photoanode. Here we have explored the application of manganese dioxide (MnO₂) and copper-doped manganese dioxide (Cu-MnO₂) nanoparticles as CE candidates for DSSCs mainly as low-cost alternatives to Pt. A simple hydrothermal method was followed to synthesize α-MnO2 and Cu-MnO2 nanoparticles at a temperature of 140 °C for 14 h. The nanoparticles were characterized to prove its electrocatalytic abilities for DSSCs. DSSC devices fabricated with 10 wt% Cu-MnO₂ as CE showed the best V_OC of 781 mV, I_SC of 3.69 mA/cm², FF of 0.50, and %PCE of 1.7 whereas Pt as CE showed V_OC of 780 mV, I_SC of 14.8 mA/cm², FF of 0.43, and %PCE of 5.83 under 0.85 Sun. The low-cost feature of using Cu-MnO₂ is encouraging to further study the factors that can improve the efficiency of DSSCs with alternative CEs to conventional Pt electrodes.     

低成本WS_2染料敏化电池对电极的低温制备

采用简单的方法,在低温条件下制作了高效的WS2对电极,并用X射线衍射仪(XRD)、显微共焦拉曼光谱仪(Raman)和扫描电子显微镜(SEM)对材料的物理特性进行了表征.WS_2对电极的电化学催化活性用循环伏安(CV)和光电流密度-电压特性(I-V)来评价.利用所制备WS_2对电极组装的染料敏化太阳能电池的光电转换效率为5.48%略低于Pt对电极(6.6%).研究表明WS_2是一种很有前景的染料敏化太阳能电池Pt对电极替代材料.     

Polypyrrole-cobalt-carbon nanocomposites as efficient counter electrode materials for dye-sensitized solar cells

In this work, we demonstrate a new kind of Pt-free counter electrode for dye-sensitized solar cells(DSCs). Polypyrrole-cobalt-carbon(PPY-Co-C) nanocomposites, with the advantages of low cost and simple preparation, show favorable catalytic activity in promoting tri-iodide reduction. The DSC composed of the PPY-Co-C nanocomposite electrode exhibits an acceptable energy conversion efficiency of 6.01%, a considerable short-circuit photocurrent of 15.33 mA cm-2, and a low charge-transfer resistance of 1.5 Ω cm2. The overall performance of PPY-Co-C is superior to the carbon counterparts and comparable with the platinum reference, rendering them efficient and promising counter electrode materials for DSCs.     

Transferred vertically aligned N-doped carbon nanotube arrays: use in dye-sensitized solar cells as counter electrodes

We prepared vertically aligned nitrogen doped carbon nanotubes (CNTs) on a rigid glass substrate or flexible plastic substrate via a 'growth-detachment-transfer' process and the vertically aligned N-doped CNT arrays are employed as counter electrodes for novel dye-sensitized solar cells.     

Fabrication of double-walled carbon nanotube counter electrodes for dye-sensitized solar sells

Double-walled carbon nanotubes (DWCNTs) have been studied for counter-electrode application in dye-sensitized solar cells (DSCs). Mesoporous TiO2 films are prepared from the commercial TiO2 nanopowders by screen-printing technique on optically transparent-conducting glasses. A metal-free organic dye (indoline dye D102) is used as a sensitizer. DWCNTs are applied to substitute for platinum as counter-electrode materials. Morphological and electrochemical properties of the formed counter electrodes are investigated by scanning electronic microscopy and electrochemical impedance spectroscopy, respectively. The electronic and ionic processes in platinum and DWCNT-based DSCs are analyzed and discussed. The catalytic activity and DSC performance of DWCNTs and Pt are compared. A conversion efficiency of 6.07% has been obtained for DWCNT counter-electrode DSCs. This efficiency is comparable to that of platinum counter-electrode-based devices.     

Plasma-based preparation of polyaniline/graphene and polypyrrole/graphene composites for dye-sensitized solar cells as counter electrodes

This study presents the preparation of graphene (GR) nanocomposites with polyaniline (PANI) and polypyrrole (PPy) through the fast, versatile and environmentally friendly process of radio frequency (RF)-plasma polymerization. Morphological characterization of the nanocomposites is performed using scanning electron microscopy (SEM) and shows that the PANI and PPy conducting polymers coated the GR surface. The surface properties of the GR nanocomposites are determined using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The prepared GR nanocomposites are then used as counter electrodes in dye-sensitized solar cells (DSSCs). The conversion cell efficiencies for iodine-doped DSSC samples are found to be 0.086%, 5.41%, and 5.60% for I₂-PANI, I₂-PANI-GR and I₂-PPy-GR, respectively, while the corresponding undoped samples reaches power conversion efficiencies of 3.82%, 1.30%, and 0.077% for PPy-GR, PANI-GR and PANI, respectively. The incident photon-to-current efficiency (IPCE) of iodine-doped composite-based DSSCs is significantly enhanced.