Alternative Counter Electrode Research Articles

2D/2D-Graphene Functionalized MXene as an Alternative Counter Electrode for Dye-Sensitized Solar Cells

2D/2D-Graphene Functionalized MXene as an Alternative Counter Electrode for Dye-Sensitized Solar Cells

Spinel cobalt-based binary metal oxides as emerging materials for energy harvesting devices: synthesis, characterization and synchrotron radiation-enabled investigation.

The synthesis and characterization of spinel cobalt-based metal oxides (MCo2O4) with varying 3d-transition metal ions (Ni, Fe, Cu, and Zn) were explored using a hydrothermal process (140 °C for two hours) to be used as alternative counter electrodes for Pt-free dye-sensitized solar cells (DSSCs). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed distinct morphologies for each metal oxide, such as NiCo2O4 nanosheets, Cu Co2O4 nanoleaves, Fe Co2O4 diamond-like, and Zn Co2O4 hexagonal-like structures. The X-ray diffraction analysis confirmed the cubic spinel structure for the prepared MCo2O4 films. The functional groups of MCo2O4 materials were recognized in metal oxides throughout Fourier transform infrared (FTIR) analysis. The local structure analysis using X-ray absorption fine structure (XAFS) at Fe and Co K-edge identified octahedral (Oh) Co3+ and tetrahedral (Td) Co2+ coordination, with Zn2+ and Cu2+ favoring Td sites, while Ni3+ and Fe3+ preferred Oh active sites. Further investigations utilizing the Fourier transformation (FT) analysis showed comparable coordination numbers and interatomic distances ranked as Co-Cu > Co-Fe > Zn-Co > Co-Ni. Furthermore, the utilization of MCo2O4 thin films as counter electrodes in DSSC fabrication showed promising results. Notably, solar cells based on CuCo2O4 and ZnCo2O4 counter electrodes showed 1.9% and 1.13% power conversion efficiency, respectively. These findings indicate the potential of employing these binary metal oxides for efficient and cost-effective photovoltaic device production.

Constructing a stable and high-performance counter electrode for QDSSCs by modifying Co3S4 hollow nanocages with CuCo–B alloy-nanosheets

Counter electrode (CE) is a key part of enhancing power conversion efficiency (PCE) and strengthening cyclic stability in quantum dot sensitized solar cells (QDSSCs). Consequently, searching for alternative and high-quality CE materials has far-reaching consequences for extending the lifetime, increasing utilization and even further achieving commercialization of QDSSCs. Herein, we put forward an idea that the Co3S4 hollow nanocages were coated with CuCo–B alloy-nanosheets, and efficient Co3S4@CuCo–B composite CE was prepared by in-situ reduction method, and applied to QDSSCs. Because of its three-dimensional hollow structure, the Co3S4@CuCo–B composite has a higher specific surface area, encourages electrolyte diffusion, and enhances QDSSC stability. Alternatively, the work function analysis shows that Co3S4 modified by CuCo–B enhances the driving force of interfacial electric field and promotes electron transfer. The photovoltaic performance of QDSSC assembled with Co3S4@CuCo–B composite CE has demonstrated competitive ability via implementing a PCE up to 8.27 %, Jsc = 26.45 mA cm−2, Voc = 0.683 V and FF = 0.46. Among them, the PCE of Co3S4@CuCo–B composite CE respectively has ∼14.4 % and 29.6 % enhancements in comparison with pure CuCo–B and Co3S4 CEs. And Co3S4@CuCo–B composite CE displays stable current density after 200 cycle tests, demonstrating excellent cyclic stability. This work suggests that Co3S4@CuCo–B composite lays the theoretical foundation for becoming a high-performance CE.

Electrochemical evaluations of reduced graphene oxide for efficient counter electrode in dye-sensitized solar cell

The design and development of an alternative counter electrode (CE) using graphene-based low-cost material for the dye-sensitized solar cell (DSSC) is the major motivation of the current research to replace the traditional platinum counter electrode. Herein, we prepared reduced graphene oxide (rGO) and investigated it for an efficient CE in DSSC. The structural and morphological properties of rGO are analyzed using FESEM, TEM and Raman techniques. The performance of I3- reduction on the CE is characterized by the EIS Nyquist plot, cyclic voltammetry, and the Tafel curve. The measured electrochemical results suggested that rGO CE has a lower charge transfer resistance (Rct), higher cathodic current density (Jrd), and higher Tafel slope as compared to graphene oxide (GO) CE, revealing that rGO CE has good catalytic activity towards the I3- reduction.

VC@C composites derived from polyoxovanadate assisted by dicyandiamide as low-cost platinum-free counter electrode electrocatalyst for dye-sensitized solar cells

Vanadium-based carbides have been applied as Pt-free counter electrodes (CEs) electro-catalysts for dye-sensitized solar cells (DSSCs) due to the advantages of earth-abundant reserves, diverse composition, ease modification, and low cost. Herein, the polyoxovanadate (NH4)2V6O16 as V source assisted by dicyandiamide (C2H4N4) as C source via simply physical mixing by ball-milling to assemble VC@C precursors. And then, five different VC@C composites derived from precursors with mass ratios of dicyandiamide to polyoxovanadate of 5:1, 10:1, 15:1, 20:1 and 25:1 at 900 °C, and further achieved power conversion efficiencies (PCEs) of 5.4%, 5.6%, 6.6%, 6.2% and 5.1% as CEs for regenerate traditional I3−/I− couple in the encapsulated DSSCs, respectively. The effects of different mass ratio of dicyandiamide on the catalytic performances of VC@C composite CEs were also assessed using cyclic voltammetry, electrochemical impedance spectroscopy and Tafel polarization experiments. The photocurrent-photovoltage (J-V) results indicated that VC@C composites CEs had high conductivity and rich number of active sites, which indicated that VC@C composites could be a cost-effective and high-performance alternative Pt-based CEs catalyst for DSSCs.

Enhanced catalytic CuCo2Se4/g-C3N4 nano-composites as counter electrodes for high-performance quantum dot sensitized solar cells

Counter electrode (CE) plays a crucial role in collecting external circuit electrons and catalyzing electrolyte reduction in quantum dot sensitized solar cells (QDSSCs). Hence, inquiry into alternative CE materials with low cost and high catalytic activity will have a profound impact on realizing the commercialization of QDSSCs. Herein, we reported the in situ growth of CuCo2Se4 nanoparticles on graphitic carbon nitride g-C3N4 nanosheets by a simple hydrothermal method to form CuCo2Se4/g-C3N4 series composites and their first application as efficient CE materials in QDSSCs. The CuCo2Se4/g-C3N4 composite has a better hierarchical structure with g-C3N4 nanosheets as the support carrier, which is conducive to reducing the agglomeration effect of CuCo2Se4 nanoparticles, accelerating electrolyte diffusion and enhancing the stability of the material. In addition, the CuCo2Se4/CN-2 composite combines the excellent catalytic performance of the ternary selenide CuCo2Se4 with the better flexibility of g-C3N4 to exhibit prominent photovoltaic performance in QDSSCs, achieving a power conversion efficiency (PCE) as high as 8.48%, Jsc = 24.46 mA·cm−2, Voc = 0.635 V and FF = 0.55. It is 29% higher than the PCE (6.54%) of QDSSCs equipped with pure CuCo2Se4 CE. A series of measuring and testing approaches containing EIS, Tafel polarization and CV cycle experiments confirm that CuCo2Se4/CN-2 CE has much higher catalytic activity and stability, which further indicates that CuCo2Se4/CN-2 composite can become a potential electrode material in the field of solar cells.

Synthesis of rGO/NiFe2O4 nanocomposite as an alternative counter electrode material to fabricate Pt-free efficient dye sensitized solar cells

Reduced graphene oxide/nickel ferrite (rNiF) nanocomposites via one pot hydrothermal procedure were synthesised. The synthesised rNiF composite was used as a catalytic counter electrode (CE) material for dye-sensitized solar cell (DSSC). HR-TEM results demonstrates that rNiF composites were firmly enfolded on rGO network, allowing easy electron transfer across the CE-electrolyte interface. The XPS survey scan spectrum of samples demonstrates that the presence of Ni, Fe, C and O in the composite structure. The large amount of porosity and specific surface area was achieved 241.71 (m2/g) and 0.521 (cc/g) by rNiF-25 sample. When rNiF-25 nanocomposite was employed as the CE catalyst in iodine electrolytes, the DSSCs achieved a power conversion efficiency (PCE) of η = 8.41 %, corresponding to 98 % of that of Pt CEs under the illumination. Also, the device maintains 88 % efficiency up to 40 days under ambient conditions without encapsulation. The IPCE of DSSCs for the Pt-based and rNiF-25 based CEs achieves maximum absorption of 81 % and 78 % at 520 nm respectively. The high catalytic activities of rNiF-25 nanocomposite are attributed to synergetic effects from the combination of active NiF structure and conductive graphene which provides efficient charge transport. These findings suggest that rNiF-25 CE can be considered as a promising alternative material to replace Pt counter electrode in DSSCs.

Poly(3,4-ethylenedioxythiophene) decorated MXene as an alternative counter electrode for dye-sensitized solar cells

Counter electrodes (CE) layer in dye-sensitized solar cells (DSSCs) are possibly the most exorbitant material due to the presence of scarce earth metal, platinum (Pt). The prospective substitution of a Pt-CE would effectively pave the way for broad commercialization of the DSSC technology. In this regard, this work is focused on the fabrication of poly(3,4-ethylene dioxythiophene) decorated MXene (PEDOT@Ti3C2Tx) composite electrode, and its performance as a CE in DSSC was tested for the replacement of high-cost Pt-CE. The 2D-Ti3C2Tx was initially synthesized by the selective chemical etching method, followed by the electro-polymerization of 3,4-ethylenedioxythiophene (EDOT) monomer on the Ti3C2Tx surface. Further, X-ray diffraction (XRD), Raman, high-resolution scanning electron microscopy (HR-SEM), and X-ray photoelectron spectroscopy (XPS) characterization results confirm the successful formation of the PEDOT@Ti3C2Tx composite. PEDOT@Ti3C2Tx-CE display a strong electrocatalytic activity toward the iodide/triiodide electrolyte and good charge transfer kinetics with low charge transfer resistance close to the performance of the Pt electrode, as shown by electrochemical experiments. On the other hand, further testing of the device fabricated with thermally decomposed Pt-CE DSSCs achieved an efficiency of 8.7% under simulated 1SUN light at AM1.5G, whilst the DSSC built with the as-prepared composite material had 7.12% efficiency under the same conditions. PEDOT@Ti3C2Tx-CE composite DSSC outperformed PEDOT-CE and Ti3C2Tx-CE DSSC in power conversion efficiency improvements (PCE), demonstrating that PEDOT@Ti3C2Tx composite possesses a strong catalytic activity with noticeable charge transfer and mass transport capabilities. Therefore, the as-fabricated composite film takes utilization of the conductivity and electrocatalytic capabilities of the two components, increasing the overall power conversion efficiency of DSSC. The 15-days stability investigation demonstrates that the PEDOT@Ti3C2Tx-CE-based DSSC exhibits a consistent performance and corrosion resistant toward the iodide/triiodide redox electrolyte. Therefore, overall performance level of the PEDOT@Ti3C2Tx-CE thus entices more study for the replacement of Pt in DSSC and is indeed evinced to be a prospective noble metal electrode contender.

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

• Synthesize α -MnO 2 and Cu doped MnO 2 nanoparticles by hydrothermal method. • Cu doped MnO 2 is utilized as counter electrode candidate for dye-sensitized solar cells. • 10 wt% Cu doped MnO 2 as CE showed the best V OC (941 mV) and I SC (3.8 mA/cm 2 ) 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 I 3 - ions and retrieves the electrons from the photoanode. Here we have explored the application of manganese dioxide (MnO 2 ) and copper-doped manganese dioxide (Cu-MnO 2 ) 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-MnO 2 as CE showed the best V OC of 781 mV, I SC of 3.69 mA/cm 2 , 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/cm 2 , FF of 0.43, and %PCE of 5.83 under 0.85 Sun . The low-cost feature of using Cu-MnO 2 is encouraging to further study the factors that can improve the efficiency of DSSCs with alternative CEs to conventional Pt electrodes.

An alternative, low-dissolution counter electrode to prevent deceptive enhancement of HER overpotential

Electrochemical hydrogen evolution reaction (HER) is typically studied in three-electrode system. In this system, several counter electrodes are commonly used to ensure fast kinetics, including Pt, gold, and glassy carbon. However, the extensive application of such electrodes has raised caveats on the contribution of the redox-active species dissolving from such electrodes and redepositing on the surface of the working electrode to the measured overpotential. Consequently, this has been frequently confused with the actual electrochemical signature of the working electrode catalyst, resulting in a deceptive enhancement in the recorded overpotential. This issue becomes more critical when the electrolysis measurements involve an activation step, necessitating the need for alternative counter electrodes that are stable, especially in acidic medium, which is commonly used as the electrolyte in HER studies. Herein, while we systematically unveil such problems, an alternative counter electrode that overcomes those problems is demonstrated. Specifically, the correlation between the working electrode area to that of the counter electrode, the dissolution rate of the counter electrode, and the potential range used in the activation/cleaning of the surface on accelerating the dissolution rate is explored and discussed in detail. Finally, commercial Ti mesh is demonstrated as an alternative emerging counter electrode, which is proven to be very stable and convenient to study the HER in acidic media.

Investigating the Morphology, Optical, and Thermal Properties of Multiphase-TiO2/MAPbI3 Heterogeneous Thin-Films for Solar Cell Applications

The present study evaluates the effect of mesoporous multiphase titanium dioxide (TiO2) nanoparticles (NPs) as an electron transporting layer and investigates the influence of phase composition on the perovskite solar cell (PSC) performances. This study also aims to evaluate PSC performance using conductive silver ink as an alternative counter electrode. The heterogeneous PSC thin-film solar cells were successfully fabricated and assembled by using a simple a doctor blade and two-step spin coating methods under ambient conditions. Scanning electron microscopy (SEM) micrograph images investigate methyl ammonium lead iodide (MAPbI3) crystal formation on the mesoporous TiO2 surface structure. Energy-dispersive x-ray spectroscopy (EDX) spectra reveal excellent qualitative and quantitative analysis corresponding to the SEM images in the TiO2/MAPbI3 heterogeneous thin films. Thermogravimetric analysis (TGA) characterization reveals that the TiO2/MAPbI3 thin films are thermally stable recording a maximum of 15.7% mass loss at 800 °C elevated temperatures. Photoluminescence spectroscopy (PL) characterized the effect of multiphase TiO2 phase transformation on the TiO2/MAPbI3 recombination efficiencies. A maximum of 6% power conversion efficiency (PCE) with the open-circuit voltage (Voc) of 0.58 ± 0.02 V and short circuit current (Jsc) of 3.89 ± 0.17 mAcm−2 was achieved for devices with an active area of 3 × 10−4 m2 demonstrating that the synthesized multiphase TiO2 nanoparticles are promising for large surface area manufacturing. Therefore, it is apparent that multiphase TiO2 NPs play a significant role in the performance of the final device.

PEDOT-Carbon Nanotube Counter Electrodes and Bipyridine Cobalt (II/III) Mediators as Universally Compatible Components in Bio-Sensitized Solar Cells Using Photosystem I and Bacteriorhodopsin.

In nature, solar energy is captured by different types of light harvesting protein–pigment complexes. Two of these photoactivatable proteins are bacteriorhodopsin (bR), which utilizes a retinal moiety to function as a proton pump, and photosystem I (PSI), which uses a chlorophyll antenna to catalyze unidirectional electron transfer. Both PSI and bR are well characterized biochemically and have been integrated into solar photovoltaic (PV) devices built from sustainable materials. Both PSI and bR are some of the best performing photosensitizers in the bio-sensitized PV field, yet relatively little attention has been devoted to the development of more sustainable, biocompatible alternative counter electrodes and electrolytes for bio-sensitized solar cells. Careful selection of the electrolyte and counter electrode components is critical to designing bio-sensitized solar cells with more sustainable materials and improved device performance. This work explores the use of poly (3,4-ethylenedioxythiophene) (PEDOT) modified with multi-walled carbon nanotubes (PEDOT/CNT) as counter electrodes and aqueous-soluble bipyridine cobaltII/III complexes as direct redox mediators for both PSI and bR devices. We report a unique counter electrode and redox mediator system that can perform remarkably well for both bio-photosensitizers that have independently evolved over millions of years. The compatibility of disparate proteins with common mediators and counter electrodes may further the improvement of bio-sensitized PV design in a way that is more universally biocompatible for device outputs and longevity.

Well-aligned ZnO nanorod array covered with ruthenium layers for alternative counter electrodes in dye-sensitized solar cells

As an alternative material for conventional counter electrodes (CEs), which are usually made from Pt/fluorine doped tin oxide (FTO), well aligned ZnO nanorod arrays have great potential, their extremely high surface area can significantly increase the number of interfacial reaction sites in contact with the electrolyte. However, in order to use ZnO nanorod arrays as CEs, inferior charge collecting efficiency is a crucial obstacle that must be overcome. Here, patterned ZnO nanorod arrays are synthesized using a hydrothermal method and an Ru metal layer is deposited using a radio frequency sputtering process. We found the optimal conditions for ZnO nanorod growth that enable us to form vertically aligned ZnO nanorod arrays on only the ZnO seed layer. The Ru metal layer, coated onto the ZnO nanorod array serves both the role of the catalyst and the charge collecting electrode, its deposition process is controlled in such a way to maximize electrode performance. The results found in this study reveal the combination of Ru metal and the ZnO nanorod array has great potential as a lower cost alternative to Pt and FTO.

Template-free synthesis of Vanadium Nitride Nanopetals (VNNP) as a high performance counter electrode for dye sensitized solar cells

The thrust of finding an alternative and noble metal free counter electrode (CE) for dye sensitized solar cells (DSSCs) encouraged the present study on new and unique structure of vanadium nitride nanopetals as counter electrode for DSSCs. Template-free vanadium nitride nanopetals were successfully synthesized by high temperature ammonia treatment of the precursor material viz. V2O5/melamine. The material analysis reveals the formation of highly crystalline vanadium nitride with mesoporous crosslinked intertwined nanopetals with pronounced electrocatalytic active sites leading to an excellent catalytic performance towards iodide/triiodide electrolyte, fast charge transfer kinetics, electron diffusion and low charge transfer resistance. The fabricated dye sensitized solar cell sandwiched with N719 dye loaded photoanode and VN nanopetals CE with an injection of iodide/triiodide electrolyte showed a significant power conversion efficiency (PCE) of 7.44%, which is higher than Pt CE (7.38%) under the same testing conditions. Results thus proved that the material is a promising candidate as an alternative counter electrode for Pt in DSSC.

Photovoltaic performance of non-covalent functionalized single-layer graphene in dye-sensitized solar cells (DSSCs)

In this study, it was aimed to fabricate new effective alternative counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). For this purpose, firstly, single-layer graphene (SLG) thin films were grown by chemical vapor deposition (CVD) method. Then, these films were separately functionalized with 1,8-cineole (ppCin/SLG), D-Limonene (ppLim/SLG) and Thiophene (ppTh/SLG) by plasma polymerization. Number of layers in CVD-grown graphene determined by Raman, transmission electron microscope (TEM) and ultraviolet–visible (UV–Vis) spectroscopy. Chemical structures of plasma polymerised (pp) thin films were investigated by Fourier transform infrared (FTIR) spectroscopy. Photovoltaic parameters of DSSCs were calculated, and electrocatalytic properties of CEs were investigated by electrochemical impedance spectroscopy (EIS). Polymer functionalization greatly enhanced the electrical conductivity and electrocatalytic activity properties of graphene compared to that of SLG. The efficiencies of DSSCs with ppCin/SLG and ppLim/SLG CEs were 1.10% and 1.02%, respectively. As a result, the cell efficiencies of ppCin/SLG and ppLim/SLG could be as alternative materials to platinum (Pt) counter electrode.

Facile fabrication of reduced graphene oxide counter electrodes by laser engraver for dye-sensitized solar cell applications

Exploring alternative Pt-free counter electrode with low cost and high electrocatalytic activity is always a main focus at the frontier of dye-sensitized solar cells (DSSCs). In this study, a desktop laser engraver was applied to reduce graphene oxide (GO) film on a fluorine-doped tin oxide (FTO) substrate, and the obtained graphene-based material was further used as counter electrode for DSSC. Additionally, this facile laser-scribing method was also adopted to fabricate a prototype of composite electrode via the combination of reduced graphene oxide (RGO) and carbon black (CB) to enhance the specific surface area and active sites. A variety of characterizations including scanning electron microscopy (SEM), Raman spectroscopy, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were conducted to investigate the microstructures and catalytic properties of these carbon electrodes. The findings reveal that both of the DSSCs with laser-scribed carbon electrodes show evidently increasing photovoltaic performance, and the DSSC based on RGO/CB composite electrode even presents a higher power conversion efficiency (PCE) of 4.49%, comparable to 4.14% of the conventional Pt-based DSSC.

Impact of Synthesis Technique on Lanthanum Doped Copper Oxide Nanocrystals, an Alternative Counter Electrode for Pt-Free Dye-Sensitized Solar Cells.

The ascendancy of a counter electrode (C.E) in a dye-sensitized solar cell (DSSC) has an unrivaled impact on the performance of the dye-sensitized solar cell, where the Pt-based C.E has set up a phenomenal benchmark against its counterparts. Due to the high cost of such noble metals, an operative and a much cost effective replacement were greatly in demand to gratify this need. To address this issue, monoclinic lanthanum doped copper oxide (CuO) nanoparticles were prepared by solution combustion and co-precipitation techniques respectively as they possess highly superior optoelectronic, catalytic and charge transfer properties. The effect of incorporating lanthanum (La) ions and the variation of synthesis technique on their structural, optical, photo-thermal and morphological properties are empirically investigated by XRD, FTIR, TEM, UV-Vis, Raman and Photoacoustic Spectroscopy (PAS). The X-ray diffraction pattern revealed the formation of La-doped CuO nanoparticles. The finger-print vibrational modes of the as-synthesized samples are confirmed by the FTIR spectra. The required optical properties of the as-synthesized nanocrystals were confirmed using UV-Vis absorption spectra, from which the bandgap was determined by Kubelka-Munk plot. The Raman modes were determined using Raman spectra, further a multi-phonon band was revealed, which was formed due to the plasmon-phonon coupling. The photothermal phenomenon was revealed using the photoacoustic spectra. The morphological investigation by TEM found the change in the morphology of the material as the synthesis route is varied. The power conversion efficiency results unveiled that the combustion-derived C.E posted a promising efficiency (η) of 0.20% and the co-precipitation derived C.E posted an efficiency of 0.02%. Overall results suggest that the combustion derived La doped CuO nanostructures exhibited substantive properties with deeper implication and also stood out to be a viable, cost-effective and self-exemplifying replacement for Pt as C.E in DSSC's.

Synthesis of highly efficient Cu2ZnSnSxSe4−x (CZTSSe) nanosheet electrocatalyst for dye-sensitized solar cells

Cu2ZnSnSxSe4-x (CZTSSe) has been reported as a promising platinum (Pt)-free counter electrode (CE) for dye-sensitized solar cells (DSSCs) with porous or crystalline structures. However, it is still challenging to develop a low-temperature method to synthesize CZTSSe electrodes with high surface area and excellent electrocatalytic activity. Herein, we present a low-temperature solution-phase synthetic approach to prepare self-organized CZTSSe nanosheets. As-synthesized CZTSSe nanosheets deposited on fluorine-doped tin oxide (FTO) substrate and applied as CE, yield a power conversion efficiency of (5.73%), which is comparable to the value we obtained using Pt-based CE (5.78%). In addition, CZTSSe nanosheets exhibit excellent electrocatalytic performance (4.60%) on carbon paper (CP) as a Pt/FTO-free CE. This impressive performance was attributed to the high specific surface area of CZTSSe with nanosheet morphology and related excellent electrocatalytic activity. Cyclic voltammetry and electrochemical impedance spectroscopy measurements confirmed that CE made of CZTSSe nanosheets have comparable catalytic activity with respect to Pt CE due to the low charge transfer resistance at the CE/electrolyte interface. The as-prepared CZTSSe CE with high reproducibility exhibits good chemical stability in the electrolyte containing. The low-temperature process, high surface area and high electrocatalytic activity help the CZTSSe nanosheets stand out as an alternative CE electrocatalyst in DSSC.

Defects at the interface electron transport layer and alternative counter electrode, their impact on perovskite solar cells performance

Herein, the electron transport layer and counter electrode interface, ETL-CE interface, for inverted-planar structure perovskite solar cells, and its influence on device performance was analyzed by means of scanning electron microscopy, atomic force microscopy, laser beam induced current and incident photon-to-current efficiency. The alternative CE was an eutectic alloy, Field’s metal (FM), which is easily deposited by drop casting technique without high vacuum conditions. Morphological analysis showed deficient physical contact at the ETL-FM interface, presenting many “empty spaces” within the range of few hundreds of nanometers. In contrast, an evaporated CE (Ca/Ag) used as reference (i.e. ETL-Ca/Ag interface) showed a smooth interface with good physical contact. Although the physical contact at the ETL-FM interface was deficient due to the deposition technique, the performance of the device with this alternative CE was comparable with the reference device. The best electrical parameters for cells with the alternative CE were: open circuit voltage (Voc) = 0.93 V, short circuit current density (Jsc) = 18.26 mA/cm2, fill factor (FF) = 0.62, and power conversion efficiency (PCE) = 10.50%; meanwhile for evaporated CE: Voc = 0.92 V, Jsc = 22.14 mA/cm2, FF = 0.57, and PCE = 11.60%. Therefore, the analysis of the ETL-FM interface and the achieved performance with FM suggests that the charge harvesting is good enough and that the observed defects between ETL-FM surfaces are not crucial for the performance of the devices.

Synthesis, Characterization and Optimization of Hydrothermally Fabricated Binary Palladium Alloys PdNix for Use as Counter Electrode Catalysts in Dye Sensitized Solar Cells.

The hydrothermal synthesis, characterization and optimization of binary palladium alloys PdNix is hereby presented in this work. Comparison of the reduction capability of the developed PdNix alloys intended for use as alternative counter electrode catalysts in dye sensitized solar cells was made relative to the standard platinum counter electrode catalyst as well as the carbon supported PdNi-rGO sample. Optimization was accomplished through varying the molar ratio of the reagents. The unsupported PdNi3 sample produced the highest catalytic efficiency with reduction current density, peak to peak potential difference and charge transfer resistance of 35 mA cm−2, 0.15 mV and 0.47 Ω respectively. Obtained results show that the unsupported PdNi3 alloy was catalytically more effective than the platinum and PdNi-rGO thus could be a viable replacement in dye sensitized solar cell counter electrodes.