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In this study, a newly synthesized macrocyclic copper complex, [Cu(C10H20N8)(C4H8N4)](BF4)2, was used for a reaction with graphene oxide. Macrocyclic copper complex/graphene‐based composite materials were prepared and applied to the counter electrodes (CEs) of dye‐sensitized solar cells (DSSCs). As the level of the macrocyclic copper complex increased, the catalytic sites on the surface of the CE increased. The results showed that the device efficiency of the composite GO/Cu (1:10) CE was 7.61%, which was better than that of the Platinum (Pt) CE (7.04%). The device efficiency of the DSSC was enhanced effectively because the electrocatalytic activity of the CE was enhanced, and the interface impedance of the device was reduced. Therefore, the macrocyclic copper complex/graphene‐based composite materials may have the potential to replace traditional Pt to increase efficiency and reduce the fabrication cost of DSSCs. [ABSTRACT FROM AUTHOR]

Abstract This study focused on synthesizing graphene oxide (GO) and macrocyclic ytterbium (Yb) complexes. The GO/Yb nanocomposite materials were prepared by performing a reaction between the secondary ammonium of macrocyclic ytterbium complexes and the GO surface functional groups (e.g., epoxide and carboxyl groups), thereby inducing the macrocyclic ytterbium complexes to uniformly cover the surface of the GO samples. In this study, different proportions of GO and macrocyclic ytterbium complexes were prepared as counter electrode (CE) materials in DSSCs; the surface morphology of the films, the composition of the structural elements, and their effects on the DSSC efficiency were discussed. The results of different analyses confirmed that a new GO/Yb nanocomposite material has been successfully synthesized in this study. Furthermore, various DSSC CEs were fabricated using different proportions of GO/Yb, and the characteristics of the DSSCs were analyzed. The results showed that the highest efficiency of the devices was 7.90%, which was higher than that of DSSCs with traditional Pt CEs. The GO/Yb nanocomposite materials can replace Pt as a CE material for DSSCs, and among all DSSC CEs prepared in this study, the DSSC with a GO/Yb (1:10) CE was the most efficient. Graphical abstract Image Highlights • Novel RGO/Yb nanocomposite materials were successfully synthesized. • The RGO/Yb composites were used as counter electrodes in DSSCs. • RGO/Yb composites exhibit high conductivity and electrochemical catalysis activity. • The RGO/Yb nanocomposite materials can replace Pt as a CE material for DSSCs. [ABSTRACT FROM AUTHOR]

In this study, macrocyclic Co complexes were successfully grafted onto graphene oxide (GO) to produce GO/Co nanocomposites with a large surface area, high electrical conductivity, and excellent catalytic properties. The novel GO/Co nanocomposites were applied as counter electrodes for Pt-free dye-sensitized solar cells (DSSCs). Various ratios of macrocyclic Co complexes were used as the reductant to react with the GO, with which the surface functional groups of the GO were reduced and the macrocyclic ligand of the Co complexes underwent oxidative dehydrogenation, after which the conjugated macrocyclic Co systems were grafted onto the surface of the reduced GO to form GO/Co nanocomposites. The surface morphology, material structure, and composition of the GO/Co composites and their influences on the power-conversion efficiency of DSSC devices were comprehensively investigated. The results showed that the GO/Co (1:10) counter electrode (CE) exhibited an optimal power conversion efficiency of 7.48%, which was higher than that of the Pt CE. The GO/Co (1:10) CE exhibited superior electric conductivity, catalytic capacity, and redox capacity. Because GO/Co (1:10) CEs are more efficient and cheaper than Pt CEs, they could potentially be used as a replacement for Pt electrodes. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrated that platinum (Pt) counter electrodes (CEs) fabricated using electrochemical deposition and chemical reduction can replace conventional high-temperature thermally decomposed Pt electrodes. In this study, Pt electrodes were fabricated using thermal decomposition, electrochemical deposition, and chemical reduction, and the influence of the different Pt counter electrodes on the efficiency of the dye-sensitized solar cells (DSSCs) was analyzed. The properties of the various Pt CEs were analyzed using scanning electron microscopy (SEM), surface area analysis, X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). DSSCs with various Pt CEs were characterized using current density-voltage (J-V), incident photo-current conversion efficiency (IPCE), and EIS measurements. The results show that the power conversion efficiencies of these three types of DSSC devices were between 7.43% and 7.72%. The DSSCs based on the Pt electrode fabricated through electrochemical deposition exhibited the optimal power conversion efficiency. Because the processes of electrochemical deposition and chemical reduction do not require high-temperature sintering, these two methods are suitable for the fabrication of Pt on flexible plastic substrates. [ABSTRACT FROM AUTHOR]

This study developed an innovative composite material using graphene oxide (GO) and macrocyclic Mn complex, which can be used as a counter electrode (CE) in dye-sensitized solar cells (DSSCs). Varying weight ratios of GO and macrocyclic Mn complex were used, and the GO/Mn composite materials were comprehensively analyzed with scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and cyclic voltammetry. The results indicate that the reaction between the GO and the macrocyclic Mn complex can be used to evenly graft the latter onto the surface of graphene. Furthermore, the redox capacity of the macrocyclic Mn complex, along with the high surface area and highly conductive graphene, can enhance the conductivity and electrochemical catalytic capacity of the CE. This study used several GO/Mn CEs for the DSSC, and the current density-voltage, incident photo-to-current conversion efficiency, and electrochemical impedance spectroscopy results all suggest that the CE made of GO and macrocyclic Mn complex with a weight ratio of 1:10 (GO/Mn (1:10)) has the greatest redox capacity and the highest device efficiency of 7.47%, which is even higher than a DSSC using platinum CE. Evidently, the GO/Mn composite material is successful as a CE for the DSSC, and because of its low cost and excellent performance, it is an ideal substitute for the expensive Platinum CE. [ABSTRACT FROM AUTHOR]

Copper oxide (CuO) and CuO/graphene nanostructured thin films were used as counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). CuO and CuO/graphene pastes were prepared and coated on fluorine-doped tin oxide (FTO) glass substrates using a doctor-blade coating method. The substrates were then sintered at 350 °C for 30 min to form CuO and CuO/graphene nanostructures. The material properties of the CuO and CuO/graphene CEs were analyzed using a scanning electron microscope, transmission electron microscope, energy-dispersive spectrometer, thermogravimetric analysis instrument, X-ray diffractometer, Raman spectroscopy, X-ray photoelectron spectrometer, ultraviolet-visible spectrophotometer, and cyclic voltammetry instrument. The CuO and CuO/graphene CEs were used to fabricate DSSCs, and the device characteristics were analyzed using current density-voltage, incident photo-to-current conversion efficiency, and electrochemical impedance spectroscopy measurements. The results showed that when CuO and CuO/graphene were used as the CEs, the device conversion efficiencies were 2.73% and 3.40%, respectively. CuO is a favorable replacement for expensive platinum (Pt) because it features a simple fabrication process and is inexpensive and abundant. Furthermore, graphene, which exhibits high carrier mobility, may be added to enhance the electrical and catalytic abilities of CuO/graphene CEs. This is the first study to examine the use of CuO and CuO/graphene for developing Pt-free CEs in DSSCs. [ABSTRACT FROM AUTHOR]

A novel series of reduced graphene oxide (RGO)/macrocyclic iron (Fe) complex hybrid materials were synthesized and then used in the production of counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). The electrode properties of various CEs were comprehensively analyzed using scanning electron microscopy, transmission electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, energy dispersive spectroscopy, Raman spectroscopy, X-ray diffraction, and cyclic voltammetry analyses. DSSCs, based on various CEs, were characterized using current density–voltage, incident monochromatic photon-to-current conversion efficiency, and electrochemical impedance spectroscopy measurements. DSSCs fabricated using the RGO/macrocyclic Fe nanocomposite CEs yielded an efficiency of 6.75%. The RGO/Fe CEs exhibited efficient electrocatalytic capability because catalytic Fe particles were uniformly distributed on the surface of RGO. The results indicated that a DSSC with a RGO/Fe CE can exhibit an efficiency comparable to that of a platinum (Pt) CE DSSC and can therefore replace conventional Pt CE DSSCs to lower the cost of solar cells. [ABSTRACT FROM AUTHOR]

In this study, the conductive polymer poly(o-methoxyaniline) (POMA) was doped with an organic acid, 1S-(+)-camphorsulfonic acid (CSA), and used to fabricate counter electrodes for dye-sensitized solar cells (DSSCs). The effects of POMA doped with various weight ratios of CSA on the efficiency of DSSCs were investigated. The properties of the POMA and POMA-CSA electrodes were comprehensively analyzed. The POMA-CSA electrodes exhibited increased surface roughness, increased crystallinity, and decreased impedance. The characteristics of DSSCs based on POMA-CSA electrodes were analyzed using photocurrent density–voltage, incident monochromatic photon-to-current conversion efficiency, and electrochemical impedance spectroscopy measurements. The experimental results revealed that the POMA-CSA(16%) electrodes exhibited the optimal electrode characteristics. The DSSC based on POMA-CSA(16%) counter electrodes reached an efficiency of 8.76%, which was higher than that of DSSCs with platinum counter electrodes. [ABSTRACT FROM AUTHOR]

In this study, graphene nanosheets (GNs) were used to fabricate novel counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). The electrode properties of various CEs were comprehensively analyzed using scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectrometry (EDS), and cyclic voltammetry (CV). DSSCs with various GN CEs were characterized using current density–voltage ( J – V ), incident photo-to-current conversion efficiency (IPCE), and electrochemical impedance spectroscopy (EIS) measurements. The results show that GN CEs sintered at 400 °C in a nitrogen atmosphere for 30 min yielded the optimal electrode properties and DSSC efficiency. This study also fabricated GN–Pt composite and GN–Pt stacked CEs for the DSSCs, and the influences of the CEs on the efficiency of the DSSCs were investigated. The results show that the GN–Pt stacked CEs yielded the optimal electrochemical catalytic properties and DSSC efficiency. The power conversion efficiency of the DSSCs based on GN–Pt stacked CEs yielded a 16.7% improvement compared with conventional Pt CEs. [ABSTRACT FROM AUTHOR]

Abstract: We report an effective way to produce nanoporous Pt counter electrodes of dye-sensitized solar cells by the glancing-angle deposition (GLAD) technique. By controlling the orientation of the substrate relative to the incident Pt vapor flux during the deposition, nanoporous films composed of inclined nm-scale columns were produced through the self-shadowing effect. Pt counter electrodes having varied nanoporous structures were characterized for their morphological and electrochemical properties, and were subjected to device studies to establish the correlation with DSSC characteristics/performances. The results suggest that the nanoporous GLAD Pt electrodes can effectively enhance active surface areas, the catalytic ability and charge exchange at the Pt/electrolyte interface of a DSSC. As a result, the quantum efficiency, short-circuit current, and power conversion efficiency of the DSSC can be enhanced by up to 12–13% with using the nanoporous GLAD Pt counter electrodes. [Copyright &y& Elsevier]

Abstract: We report an effective and yet simple way to produce nanotextures in Pt counter electrodes of dye-sensitized solar cells (DSSCs) by simply depositing Pt thin films on convenient textured substrates, and investigate the influences of textures in Pt counter electrodes on characteristics and performances of DSSCs. Pt counter electrodes having varied textures were characterized for their morphological and electrochemical properties, and were subjected to device studies to establish the correlation between Pt textures and DSSC characteristics/performances. The results suggest that the highly textured Pt electrodes can effectively enhance active surface areas and the catalytic ability for ions reduction and charge exchange at the Pt/electrolyte interface of a DSSC. As a result, the quantum efficiency, short-circuit current, and power conversion efficiency of the DSSC were enhanced by 9–10% with using the highly textured, large-roughness, and high-surface-area Pt counter electrodes. [Copyright &y& Elsevier]

Abstract: We report a method to fabricate nanostructured Pt counter electrodes for DSSCs using self-assembly nanosphere monolayers. The spin-coating in combination with the water transfer technique was adopted to produce low-defect, large-area and close-packed (hexagonal) self-assembly nanosphere monolayers on glass substrates. By vacuum deposition of SiO2 through pores of self-assembly nanosphere monolayers, arrays of SiO2 nanodots were formed on glass substrates. Further blanket deposition of Pt on such nanostructured substrates gave nanostructured Pt counter electrodes for DSSCs. DSSCs using such nanostructured Pt electrodes showed enhanced short-circuit currents, spectral responses, and power conversion efficiencies, compared to DSSCs using unstructured Pt counter electrodes. Investigations by electrochemical impedance spectroscopy revealed the reduction of charge-transfer resistances for the Pt/electrolyte interface in using nanostructured Pt counter electrodes, due to increase of the active surface areas and thus the electro-catalytic ability (activity). [Copyright &y& Elsevier]

Graphene, as one of the carbon-based materials, is considered to be a potential replacement for platinum and has been widely used as a counter electrode in dye-sensitized solar cells to achieve low-cost and high electrocatalytic materials. In this work, we synthesized a nitrogen-sulfur-coordinated iron complex as a source of heteroatoms, and prepared iron-nitrogen-sulfur co-doped reduced graphene oxide (FeNS-rGO) composite material by mixing with different mass ratios of graphene oxide (GO) and thermal annealing under nitrogen at 400 °C. The sintered GO was transformed into rGO, which increased the conductivity of materials, while the doping of nitrogen and sulfur atoms enhanced the carrier mobility and conductivity of the material. The distribution of Fe on graphene also improved the catalytic performance of material. FeNS-rGO (5:1), used as the CE in DSSC, showed superior reduction catalytic activity for I−/I 3 − compared to platinum and demonstrated an excellent power conversion efficiency of 8.17 %, which outperformed platinum. This proves that the graphene composite material doped with iron, nitrogen, and sulfur has excellent performance and can be used as a substitute for platinum. [Display omitted] • A planar nitrogen-sulfur coordinated iron complex as a heteroatom dopant. • The iron-nitrogen-sulfur co-doped reduced graphene oxide (FeNS-rGO) improves the conductivity and catalytic performance. • The FeNS-rGO exhibits excellent electroactivity for the reduction of triiodide ions (I 3 −) in DSSCs. • The DSSCs incorporating the FeNS-rGO as counter electrodes demonstrate high power conversion efficiencies. [ABSTRACT FROM AUTHOR]

Covalent bond–grafted soluble poly( o -methoxyaniline)–functional graphene oxide (POMA-FGO) nanocomposite materials were prepared and doped with 1S-(+)-camphorsulfonic acid (CSA) as counter electrodes (CEs) for realising dye-sensitised solar cells (DSSCs). DSSCs with the POMA-FGO and POMA-FGO-CSA CEs exhibited substantially reduced interfacial impedance, which may be attributed to dual improvement from the well-dispersed FGO and the doping effect of CSA. Therefore, the efficiency levels of the DSSCs fabricated with the POMA-FGO CEs were higher than those of the DSSCs fabricated with the POMA CEs. When CSA was doped with the CEs, the efficiency of the DSSC was further enhanced. In particular, the efficiency of a DSSC based on the POMA-FGO (0.5%)-CSA (16%) CEs reached 8.81%, which was higher than that of a DSSC with a conventional platinum electrode. Therefore, POMA-FGO-CSA–based CEs can serve as a potential alternative to expensive platinum CEs. [ABSTRACT FROM AUTHOR]

Nanocomposites using graphene hybrid with a fully conjugated macrocyclic nickel complex were successfully prepared via a simple redox reaction of graphene oxide and an octaaza-bis-α-diimine macrocyclic nickel complex. The dye-sensitized solar cells fabricated with the graphene/macrocyclic nickel complex-based nanocomposite counter electrode reached a power conversion efficiency of 8.30%, which was higher than that of the platinum counter electrode under the same conditions. The nanocomposites exhibited excellent electrocatalytic performance for the reduction of triiodide due to the well-distributed catalytic nickel center on the graphene surface. [ABSTRACT FROM AUTHOR]