An overview of the preparation and application of counter electrodes for DSSCs

Dye-sensitized solar cells (DSSCs) are potential products for the next generation of photovoltaic technology, which is one of the research hotspots in photovoltaics. The counter electrode in DSSCs collects electron in the external circuit and catalyzes the reduction of the redox electrolyte and hole transport in the solid electrolyte. Thus, it undoubtedly has an important impact on the photovoltaic performance, long-term stability, and cost of DSSCs. In this work, the materials of counter electrodes are classified into metals, carbon materials, conductive polymers, and inorganic compounds. The preparation, mechanism, conversion efficiency, and properties of counter electrodes are reviewed.

Emergence of Ni-Based Chalcogenides (S and Se) for Clean Energy Conversion and Storage

Nickel chalcogenide (S and Se) based nanostructures intrigued scientists for some time as materials for energy conversion and storage systems. Interest in these materials is due to their good electrochemical stability, eco-friendly nature, and low cost. The present review compiles recent progress in the area of nickel-(S and Se)-based materials by providing a comprehensive summary of their structural and chemical features and performance. Improving properties of the materials, such as electrical conductivity and surface characteristics (surface area and morphology), through strategies like nano-structuring and hybridization, are systematically discussed. The interaction of the materials with electrolytes, other electro-active materials, and inactive components are analyzed to understand their effects on the performance of energy conversion and storage devices. Finally, outstanding challenges and possible solutions are briefly presented with some perspectives toward the future development of these materials for energy-oriented devices with high performance.

Optimizing graphene content in a NiSe/graphene nanohybrid counter electrode to enhance the photovoltaic performance of dye-sensitized solar cells

Nickel selenide (NiSe) nanoparticles were grown on graphene nanosheets (GN) with different mass ratios to obtain their corresponding NiSe/GNx (x = 0.25 to 1.00) nanohybrids by a facile in situ hydrothermal process to integrate the advantages of the high specific surface area of graphene and the homogeneously immobilized catalytic sites of NiSe. The nanohybrid with a mass ratio of 1 : 0.50 (i.e., NiSe/GN0.50) exhibited higher electrocatalytic activity and electrolyte diffusion. Thus, NiSe/GN0.50 exhibited an improved photo-conversion efficiency (PCE) of 12% (η = 8.62%) compared to a standard Pt (η = 7.68%)-based dye-sensitized solar cell (DSSC). This improved PCE mainly originated from the catalytic ability of NiSe and the multiple interfacial electron transfer pathways of graphene, resulting in enhanced charge transfer and fast tri-iodide reduction kinetics at the counter electrode/electrolyte interface. The results obtained from the cyclic voltammetry (CV), electrochemical AC-impedance (EIS) and Tafel polarization studies validated the synergistic effects of NiSe and GN and the high potential of this nanohybrid as an efficient counter electrode (CE) for DSSCs.

High Performance of 3D Symmetric Flowerlike Sb2 S3 Nanostructures in Dye-Sensitized Solar Cells

Antimony sulfide (Sb₂ S₃ ) is an important chalcogenide belonging to Group V-VI that is suitable for application as a photoelectric material in the fields of photocatalysis, photoconductive detectors, ion conductor materials, and solar energy conversion materials. Herein, a facile, one-step hydrothermal method is used to synthesize a 3D, symmetric, flowerlike Sb₂ S₃ nanostructure. The structure was composed of numerous nanoneedles, which provided a large void fraction and specific surface area. Characteristic mesoporous structures of the samples contribute to excellent performance. If they were used as counter electrode materials in dye-sensitized solar cells, the photoelectric conversion efficiency was as high as 7.12 %, whereas the photoelectric conversion efficiency of platinum was only 6.46 %. Furthermore, according to the results of cyclic voltammetry, electrochemical impedance spectra, and Tafel polarization testing, the obtained Sb₂ S₃ samples have better electrocatalytic activity and charge-transfer ability than that of Pt, and thus, can be regarded as good substitutes for precious metals.