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Currently, most of CuS counter electrodes (CEs) used in quantum dot-sensitized solar cells (QDSSCs) are provided with a thickness of hundreds of nanometers or even several microns. Considering the CE with low thickness having many advantages, thin CuS films with thickness ranging from 47 nm below to 115 nm have been synthetized in this paper via chemical bath deposition (CBD) method with different bath concentrations. A power conversion efficiency (PCE) of 3.25% has been achieved utilizing CuS thin films a thickness of only 64 nm as CEs in QDSSCs without any structural optimization, which is higher than the value of the cell employing CuS CE with thickness of 2.8 μm. Electrochemical impedance spectroscopy, Tafel polarization, and two-point current-voltage measurements are used to investigate the electrocatalytic and conductive performance of CuS CEs with different thickness. Owing to the highest electrocatalytic capacity and good conductivity of the 64 nm-thick CuS CE, QDSSC assembled with this CE has reached relatively high PCE under one sun illumination (100 mW cm −2 , AM 1.5). In addition, cyclic voltammetry measurements indicate that the thin CuS CE has a good stability against the polysulfide electrolyte. [ABSTRACT FROM AUTHOR]

Vacuum thermal evaporated Cu x S (VTE-Cu x S) film on fluorine-doped tin oxide substrate has been investigated as counter electrode (CE) for quantum dot-sensitized solar cells (QDSCs) with polysulfide electrolyte. The photovoltaic parameters of QDSCs show an obvious dependence on the annealing time of Cu x S film, and the maximum power conversion efficiency of 3.16 ± 0.05% under one sun illumination (100 mW cm −2 , AM 1.5 G) was obtained when the VTE-Cu x S CE was annealed at 270 °C for 300 s (VTE-Cu x S-300s CE). Electrochemical impedance spectroscopy, Tafel polarization, and cyclic voltammetry measurements have been employed to investigate the electrocatalytic activity of VTE-Cu x S-300s CE. The electrocatalytic activity of the VTE-Cu x S-300s CE is much higher than that of Pt CE, and is slightly higher than that of Cu 2 S CE in situ prepared on brass sheet. In particular, VTE-Cu x S-300s CE holds high diffusion velocity of S 2− /S n 2− in polysulfide electrolyte, and the stability of its electrocatalytic activity in polysulfide electrolyte is better than that of Pt and Brass-Cu 2 S CEs obviously. [ABSTRACT FROM AUTHOR]

Abstract: The Cu2ZnSnS4 (CZTS) thin films with uniform and porous surface feature with the pore size of 100-200nm were successfully prepared by pyrolysis procedure using the methanol solution containing copper chloride dihydrate (0.06mol dm−3), zinc chloride (0.03mol dm−3), stannous chloride dihydrate (0.03mol dm−3), thiourea (0.48mol dm−3) and deionized water (1.92mol dm−3) as precursor solution at 380°C in air atmosphere. Electrochemical impedance spectroscopy was applied to evaluate the electrochemical catalytic activity of the pyrolysis CZTS thin films for redox couple of Sn 2-/S2− and the charge transfer resistance was 64.08Ω using the pyrolysis CZTS thin film obtained by repeating the procedure of dipping the FTO substrate into the precursor solution and heating at 380°C for 7 cycles. The assembled quantum dot-sensitized solar cells gave an open-circuit photovoltage of 0.52V, a short-circuit photocurrent density of 12.96mAcm−2, and a fill factor of 0.38, corresponding to the photoelectric conversion efficiency of 2.56%. Because the pyrolysis procedure was a facile, low cost and vacuum-free process, and had the advantage of obtaining various porous microstructure thin films and allowing deposition over large areas, the pyrolysis CZTS thin films can serve as an effective counter electrode for QDSCs. [Copyright &y& Elsevier]

Herein, a facile top-down approach and a post-synthetic etching strategy were reported to prepare high-quality sulfur quantum dots (H-SQDs), which were first discovered with a boosted anodic electrochemiluminescence (ECL) emission in an aqueous solution. Elaborate investigations demonstrated that the significantly improved ECL properties of H-SQDs were attributed to the reduced size for inherent brightness, the highly passivated surface, and enhanced charge injection/transfer capacities after the post-synthetic hydrogen peroxide etching. The underlying anodic ECL mechanism and the redox nature of H-SQDs were studied in detail for the first time, indicating a direct oxidation ECL mechanism with tri-n-propylamine as the "oxidation-reduction" coreactant. Beyond that, the as-obtained H-SQDs also featured low cost, remarkable monodispersity, excellent water-solubility, and good biocompatibility, illustrating their great potential in ECL bioanalysis. As a proof-of-concept, H-SQDs, an emerging ECL emitter with high ECL efficiency, was utilized to construct an "off-on" ECL biosensor for sensitive glutathione (GSH) assay. This work not only promotes the exploration of novel ECL emitters, but also provides a new perspective for the application of SQDs-based ECL biosensor in clinical diagnosis. [ABSTRACT FROM AUTHOR]