Composite Counter Electrode Research Articles

Efficiency and stability improvements for room light dye-sensitized solar cells in the presence of electrochemically fabricated composite counter electrodes

Electrochemical methodologies including constant current, constant potential and cyclic voltammetry (CV), as well as the sputter coating, are utilized to fabricate the poly(3,4-ethylene dioxythiophene) (PEDOT), platinum (Pt), and their composite films with layer-by-layer (Pt/PEDOT) and homogenous (PEDOT-Pt) structures. These films are utilized as counter electrodes of dye-sensitized solar cells (DSSCs). To achieve high cell efficiencies, the thickness of Pt and PEDOT, as well as the structure of composite films are regulated. The results show that PEDOT/Pt and PEDOT-Pt films demonstrate, respectively, the best and worst cell efficiencies. The X-ray diffraction and X-ray photoelectron spectroscopy analysis indicate that PEDOT and Pt have slight interaction in the PEDOT/Pt film, and the Pt preserves a crystalline structure. On the contrary, the interaction of PEDOT and Pt in the PEDOT-Pt film is high, resulting in an amorphous Pt structure. The crystalline Pt and its interaction with PEDOT are considered to be the main reason resulting in the high efficiencies of the corresponding cells. By applying this PEDOT/Pt counter electrode on DSSCs, the charge transfer at the counter electrode/electrolyte interface is significantly increased, and the cells can achieve efficiencies as high as 8.97% and 15.35%, respectively, under one-sun and room-light (200 lux) conditions. • PEDOT/Pt counter electrodes (CEs) is prepared using electrochemical methods. • This CE has the uniform layer of PEDOT/Pt and high surface area. • The PEDOT/Pt CE has high electrocatalytic activity towards I 3 − ions reduction. • The DSSCs using the PEDOT/Pt CE achieves an efficiency of 15.35%. • The cells using the PEDOT/Pt CE has high stability.

Interface architecture of low-cost and stable three-dimensional composite counter electrodes for QDSCs

CuS or nanographite as active sites were loaded into acidized MWCNT to build 3D CEs used in QDSCs. The interface and microstructure were modified for faster electron transfer on electrolyte/CE interface by modifying the preparation routes.

A new research perspective: The application of potassiated alloy/carbon composite counter electrode in fundamental and practical research of K-ion batteries

Many efforts were made to modify cathode materials for K-ion batteries to improve their performance. However, the improvements are not so significant. Herein, we show that the performance of host materials are limited by metal K counter electrode, which leads to underestimation of materials. With a potassiated alloy/carbon composite counter electrode, the Prussian blue analogue cathode can show outstanding rate capability at 5000 mA g−1 and operate 1000 cycles without capacity fading. Besides, when the anode utilization increased to 72.7%, the battery parameters, such as lifespan, energy and power density, were also promising. This work offers a new perspective for both fundamental and practical research of K-ion batteries.

Screen-printed carbon black/SiO2 composite counter electrodes for dye-sensitized solar cells

Platinum (Pt)-based counter electrodes (CEs) are promising electrocatalysts for dye-sensitized solar cells (DSSCs). However, replacing the expensive Pt with low-cost materials and comparable catalytic activity still a big challenge. Here, we prepared CB-SiO2 composites by blending various weights of SiO2 (1, 3, and 5 wt%) with carbon black (CB), followed by screen printed onto the FTO substrate to utilized as CEs for DSSCs. In comparison with pure CB, CB-SiO2 composite CEs showed higher transferability and higher electrocatalytic activity toward I3-/I- redox couple. Among all, CB-SiO2-1% composite CE with 4 µm showed the best catalytic performance, and the related DSSC showed a power conversion efficiency of 6.38%. Increasing the CE thickness significantly enhances the catalytic ability and the total performance of the assembled devices, whereas the power conversion efficiency of the DSSC with CB-SiO2-1% composite CE in 8 µm thick was 7.99%, which is close to that achieved by Pt-based device under the same conditions.

Low cost, platinum free counter electrode with reduced graphene oxide and polyaniline embedded SnO2 for efficient dye sensitized solar cells

A composite consisting of Reduced Graphene Oxide (RGO), Tin Oxide (SnO2) nanoparticles and Polyaniline (PANI) conducting polymer was studied as a potential counter electrode material for Dye Sensitized Solar Cells (DSSCs). This RGO/SnO2/PANI composite CE was fabricated by spray method and used as an alternative to Platinum (Pt) counter electrode (CE). In the fabrication of RGO/SnO2/PANI composite CEs, several optimizations were carried out to obtain the optimum RGO sintering temperature and the optimum amounts of RGO, SnO2 and PANI. The photovoltaic performance of the DSSCs based on the newly prepared CEs was studied by using I-V measurements. The efficiency of the DSSC with the CE with optimized RGO/SnO2/PANI composition having 9.8 μm thickness was 7.92% under the 100 mW cm−2 (1.5AM) light illumination. After the TiCl4 treated TiO2 photoanode was used, the maximum power conversion efficiency of the DSSC based on the RGO/SnO2/PANI composite CE was increased to 8.68%, which corresponds to an impressive 94% of the efficiency of 9.22% obtained for the control DSSC made with Pt CE and TiCl4 treated photoanode measured under same light illumination. These composite CEs were characterized by X-ray diffraction, Raman spectra, FTIR spectra, SEM and TEM. Cyclic voltammetry (CV) analysis showed the excellent electro-catalytic activity of the composite CE. With high energy conversion efficiency and improved charge-transfer process of DSSCs in combination with simple preparation and relatively low-cost technique, the RGO/SnO2/PANI composite electrode demonstrates the beneficial use of this novel composite material as CEs in DSSCs.

Highly-dispersed CoS2/N-doped carbon nanoparticles anchored on RGO skeleton as a hierarchical composite counter electrode for quantum dot sensitized solar cells

Hierarchical nanostructures with tailored components and architectures have attracted widespread interest in improving the performance of electrocatalysts, but the construction of exquisite structures with remarkable electrocatalytic performance is still challenging. Herein, the hierarchical CoS2/NC-RGO composite is designed via a delicate yet facile three-step process, including in-situ growth of ZIF-67, carbonization, and vulcanization. The key preparation step is that GO sheets and the O-20 surfactant are introduced simultaneously into the process of ZIF-67 preparation to obtain the precursor of the hierarchical structure. The composite employed as the counter electrode in the polysulfide electrolyte exhibits a low charge transfer resistance of 1.07 Ω, and the CdS/CdSe co-sensitized quantum dot sensitized solar cell obtains a PCE up to 5.14%. The successive cyclic voltammetry test results prove that it exhibits ultrastrong durability in the polysulfide electrolyte. The excellent performance is mainly due to the well-design of the RGO conductive skeleton and the CS/NC nanoparticles that are uniformly and tightly anchored on the RGO surface. This work provides a new perspective for the preparation of novel and high-efficient hierarchical carbonaceous composite CEs for QDSSCs.

Quasi-solid-state dye-sensitized solar cells utilizing TiO2/graphite composite counter electrode and TiO2/N719 sensitizer photoelectrode for low-cost power generation

Quasi-solid-state dye-sensitized solar cells utilizing TiO2/graphite composite counter electrode and TiO2/N719 sensitizer photoelectrode for low-cost power generation

A low-cost, vein graphite/tin oxide nanoparticles based composite counter electrode for efficient dye-sensitized solar cells

Performance of dye sensitized solar cells made with a novel, low cost graphite/SnO2 composite counter electrode is demonstrated. The best performance is exhibited by the composite made with 3.0 ml colloidal SnO2 solution and 0.05 g of graphite powder, sintered at 450 °C. The solar cell efficiency was increased from 6.02% for pure vein graphite to 7.95% for optimized composite graphite/SnO2 electrode, which is 86% of the efficiency of 9.25% obtained for Pt electrode. This impressive 32% increase in efficiency can be associated with highly porous nanostructure of the graphite/SnO2 composite providing more reaction sites for triiodide ion reduction as confirmed by Scanning Electron Microscopy, X-ray diffraction and Raman Spectroscopy. Excellent electrocatalytic activity exhibited by the new counter electrode is confirmed by Electrochemical Impedance Spectroscopy and Cyclic Voltammetry, further supported by Tafel plot analysis. This result provides a cost-effective method to fabricate efficient counter electrodes for dye sensitized solar cells.

Sb2S3 entrenched MWCNT composite as a low-cost Pt-free counter electrode for dye-sensitized solar cell and a viewpoint for a photo-powered energy system

The current research interest is to use Sb2S3 entrenched Multi-Walled Carbon Nanotubes (MWCNT) composite as Pt-free counter electrode in dye-sensitized solar cells (DSSCs) and also to test its usage as a supercapacitor. Hence here, Sb2S3 nanorods with different concentrations of MWCNT have been synthesized by facile microwave irradiation technique and are used as a counter electrode in Pt-free DSSCs and also tested for supercapacitance. Crystalline structure, shape, and quantum states have been elucidated using XRD, TEM, and XPS spectra, respectively. Among all, Sb2S3/CNT30 composite counter electrode delivers the highest Power Conversion Efficiency (PCE) of 5.02% with a short circuit current (JSC) of 12.68 mA cm−2 and open-circuit voltage (VOC) of 0.68 V. The improvement observed is due to the lower peak-to-peak separation (Epp), higher exchange current density (J0) and lower charge transfer resistance (RCT). The obtained PCE is compared with the standard Pt-based counter electrode (PCE~5.8%) and discussed. This composite is also found to be a suitable material for the supercapacitor. Among the electrodes, Sb2S3/CNT100 exhibits the highest specific capacity of 228 C g−1 with 1 Ag−1 with the capacitive retention of ~92.5% over 1000 charge-discharge cycles, which also reveals its ability for energy storage. The excellent capacitive and photovoltaic output highlights the promise of Sb2S3/MWCNT for photo-supercapacitor devices.

CdS nanosheets as electrode materials for all pseudocapacitive asymmetric supercapacitors

Metal sulphides have recently been explored as a very promising pseudocapacitor electrode, owing to their unique physical, electronic and electrochemical properties. This study reports the synthesis and pseudocapacitor applications of 2D cadmium sulphide (CdS) nanosheets deposited on Ni foam via electrophoretic deposition method. Comprehensive morphological and electrochemical analyses were performed to elucidate the correlation between the structural features of CdS and their charge storage properties. The single electrode characterizations of CdS could exhibit a specific capacitance as high as 1165 F g–1 at 2 mV s–1. An asymmetric supercapacitor prototype was also fabricated using the CdS nanosheets with ceria–titania nanotube composite (CeO2–TNT) counter electrode. The device could exhibit an energy density as high as 14.58 Wh kg–1 at a power density of 1.9 kW kg–1. At the end of 2000 cycles, the device could retain 100% of its initial capacitance.

Design and fabrication of Pt-free FeNi2S4/rGO hybrid composite thin films counter electrode for high-performance dye-sensitized solar cells

In this work, we synthesized FeNi2S4/rGO composites as Pt-free counter electrode (CE) by one step hydrothermal method. Complete investigations of phase evolutions by XRD patterns and TEM indicate spinel structure with nanosheets and nanospherical morphologies. The individual spherical-shaped nanoparticles (30–35 nm) of FeNi2S4 were exploited on the 2D ultrathin rGO nanosheets surface. This is useful for the provision of further electrolyte adsorptions and responsive electrocatalytic sites. The DSSC constructed with FeNi2S4/rGO hybrid composite CE showed a conversion efficiency of 9.98%, better than that by FeNi2S4 CE (4.87%) and also commercial Pt (6.21%). The outstanding efficiency of the FeNi2S4/rGO hybrid composite CE is even better than commercial Pt and is an effective alternative to Pt CE in the DSSCs.

Study of Microwave-Assisted MoS2 and Graphene Composite Counter Electrode for Dye-Sensitized Solar Cells

Graphene-MoS2 composites were synthesized via one-step microwave-assisted chemical bath deposition and used as counter electrodes for dye-sensitized solar cells, instead of traditional Pt film which has high cost and poor stability. The effects of graphene additive amount on the performance of cells were studied. The results reveal that sheet porous structure graphene and MoS2 particles has been incorporated tightly, which is the benefit of electrical conductivity and catalysis ability. A maximum efficiency of 6.3% has been achieved under 100 mW cm−2 illumination when the Mo:C is 1:1.

Carbon black/SnSe composite: a low-cost, high performance counter electrode for dye sensitized solar cells

Platinum (Pt) has long been used as the most dominant counter electrode (CE) in dye-sensitized solar cells (DSSCs). Yet, its high price is a challenging factor for realizing the DSSCs practical applications. In this study, we propose a CE that is based on the composite of low-cost carbon black and thin selenide materials We synthesized the SnSe nanoparticles using the facile hydrothermal method and prepared a composite with commercial carbon black nanoparticles. We show that the composite which is used as the CE in TiO2-based DSSCs has a performance comparable to that of Pt CEs. The good performance of the composite is achieved through the adjustment of the CE porosity which utilizes the redox process with the electrolyte. Our best cell with a composite CE showed an efficiency of 5.0% with open circuit voltage of 660 mV, short circuit current density of 12.4 mA/cm2 and fill factor of 62% which was very competitive with traditional Pt CE with 5.7% efficiency.

MoS2/ZIF-8 derived nitrogen doped carbon (NC)-PEDOT: PSS as optically transparent counter electrode for dye-sensitized solar cells

A few-layered MoS2 successfully grown on the nitrogen-doped carbon (NC) derived from zeolitic imidazolate framework (ZIF-8) via the hydrothermal method. A small portions of the obtained MoS2/NC composite blended with Poly (3, 4-ethylenedioxythiophene poly styrene sulfonic acid)PEDOT: PSS(as a conductive binder and utlized as counter electrode (CE) for dye-sensitized solar cells (DSSCs). The spin-coated MoS2/NC-PEDOT: PSS composite on Fluorine-doped Tin Oxide (FTO) glass not only possesses promissing catalytic ability toward the I3-/I-and [Co(bpy)3]2+/3+ redox mediators but also displayed considerable optical transparency in the visible range thus used to fabricate bi-facial DSSCs. The assembled bi-facial devices with MoS2/NC-PEDOT: PSS composite CEs showed an excellent power conversion efficiency (PCE) under both the front and the rear irradiations. The PCE of the device with 5% MoS2/NC-PEDOT: PSS composite CE and I3-/I- redox couple are 7.67 and 4.54%, under the front and rear irradiation respectively. Also, the values of the device with the same composite CE and [Co(bpy)3]2+/3+ redox mediator are 7.87 and 5.34% under the front and rear irradiation, respectively. The optimum performance of the devices with the prepared CEs and both redox systems are comparable with Pt-based devices. Thus, the MoS2/NC-PEDOT: PSS composite CEs are recommend being a promising Pt-free CEs for DSSCs.

Bifacial DSSC fabricated using low-temperature processed 3D flower like MoS2 - high conducting carbon composite counter electrodes

3D flower-like MoS2 nanostructures are synthesised using hydrothermal method at different S:Mo ratios. The grown MoS2 nanostructures exhibit 2H-MoS2 phase with P63/mmc space group, which can be inferred from XRD results. The calculated lattice parameters and inter planar spacing values are in good agreement with the literature. FESEM images show flower like morphology of the grown nanostructures. HRTEM micrographs are used to examine microstructural properties and to determine the interplanar spacing (d). The peaks observed in Raman spectra at ∼380 and ∼404 cm−1 are designated to E2 g1 mode and A1g mode respectively. Elemental analysis is carried out using XPS analysis. Counter electrodes (CE) for dye sensitised solar cells (DSSC) are fabricated using MoS2-high conductive carbon paste (HCP) composite. Simple spin coating method is used to deposit CE with a low annealing temperature of 80 °C which is suitable for even plastic substrates. Using Nyquist and Bode plot, series resistance (9.02 Ω cm2), charge transfer resistance (17.48 Ω cm2) and electron lifetime (63 ms) is calculated. The fabricated DSSC shows a power conversion efficiency of 4.50 % when illuminated from the front side whereas 2.40 % in the case of rear illumination.

Investigating the Performance of Carbon Black/Tin Selenide Composite As the Counter Electrode in Dye Sensitized Solar Cells

The counter electrode (CE) is an essential component of dye sensitized solar cells (DSSC). Currently, platinum (Pt) is the most widely used CE in DSSCs but it is an expensive material and new lower cost materials are required to replace Pt. In this study, we prepare different carbon black/tin selenide composite CEs using a facile hydrothermal method and employ them in TiO2-based DSSCs. It is shown that the low-cost composite CEs demonstrate very promising electrocatalytic and charge transport properties, and a carbon black/SnSe CE with the weight ratio of 80% can achieve an open circuit voltage of 660 mV and short circuit current density of 12.4 mA/cm3 with a fill factor of 62% which gives an efficiency of 5% that is comparable to that of Pt DSSCs. The results of this paper are confirmed via XRD, FESEM, EDS, cyclic voltammetry, J-V measurement and IPCE analyses.

Three-dimensional graphitic C3N4/CuS composite as the low-cost and high performance counter electrodes in QDSCs

As an essential working part in quantum dots sensitized solar cells (QDSCs), the counter electrode (CE) performs the function of extracting electrons form external circuit and catalyzing the reduction of electrolyte. To improve photovoltaic performance of cells, a new novel composite CE composed of graphitic C3N4 (g-C3N4) nanosheets and CuS nanoparticles is prepared on FTO glass via chemical bath deposition method. CuS nanoparticles can be successfully deposited on g-C3N4 nanosheets according to XRD, EDX, SEM and TEM results. A fast electron transport network can be constructed in 3D architecture formed with g-C3N4 nanosheets and CuS nanoparticles, which can afford multi-direction channels for electron transport and accessible catalytic active sites for reduction of polysulfide electrolyte. The synergistic effect of composite CE with continuous conductive network structure shows the excellent catalytic activity and fast electron mobilization. Electrochemical impedance spectrum reveals that the electrochemical property of g-C3N4/CuS composite CE in QDSCs has been changed significantly with the different composition of g-C3N4 and CuS, which is utilized to analyze why QDSC based on CN/30CuS CE shows the best photovoltaic properties of PCE of 5.10%. The new g-C3N4/CuS composite CE with the merits of low cost, easy processing and considerable photovoltaic performance is beneficial to large scale commercial use of three-generation solar cells.

A dye-sensitized solar cell based on magnetic CoP@FeP4@Carbon composite counter electrode generated an efficiency of 9.88%

We present a facile systematic hydrothermal-phosphorization processing procedure for in situ growth of CoP@FeP4 on carbon paper, which could be used efficient counter electrodes in DSSCs with enhanced efficiency of 9.88%, much higher than that of the Pt (7.49%) CE.

High Performance Dye-Sensitized Solar Cells Based on Electrospun MoS2-Carbon Nanofiber Composite Counter Electrode

MoS2-carbon nanofiber composites were prepared via electrospun technique with ammonium thiomolybdate(VI) and PVP. The effects of thermal pretreatment on the morphology of material were studied. The results demonstate that the composite nanofiber with pretreatment shows a uniform diameter and lots of small size MoS2 particles inside with porous structure. When the composites was used as counter electrodes in dye-sensitized solar cell, a maximum efficiency of 5.7% has been achieved due to the combination of electrical conductivity and catalysis ability from MoS2-carbon nanofiber composites.

In situ synthesis of ZnFe2O4 rough nanospheres on carbon nanofibers as an efficient titanium mesh substrate counter electrode for triiodide reduction in dye-sensitized solar cells

There is no doubt that counter electrode (CE) plays a vital role in dye-sensitized solar cells (DSSCs). Herein, Zinc Ferrite/carbon nanofibers (ZnFe2O4/CNFs) composite is successfully fabricated by electrospinning and hydrothermal method and coated on titanium (Ti) mesh as an efficient CE material, which is further applied to DSSCs. The Ti mesh has been done as conductive substrate to make the DSSCs have smaller transmission resistance, great stability and sustainable utilization. Via repeated measurements, the ZnFe2O4/CNFs CE which is prepared on Ti mesh exhibits good power conversion efficiency (PCE) of 9.05%, which is higher than commercial Platinum (Pt) fluorine-doped tin oxide (FTO) CE (7.21%) and CNFs Ti mesh CE (7.80%) under the same conditions. Most interestingly, the CNFs CE that prepared on Ti mesh has higher PCE than Pt CE, this is mainly due to the use of Ti mesh which is more conducive to the interface transport of iodine ion and electron transfer rate. All of these results indicate that ZnFe2O4/CNFs composite Ti mesh CE has high electrochemical performance and can be favorable for low-cost efficient DSSCs application.