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Pt is a classical catalyst that has been extensively used in fuel cell and solar cell electrodes, owing to its high catalytic activity, good conductivity, and stability. In conventional fiber-shaped solar cells, solid Pt wires are usually adopted as the electrode material. Here, we report a Pt nanoparticle-adsorbed carbon nanotube yarn made by solution adsorption and yarn spinning processes, with uniformly dispersed Pt nanoparticles through the porous nanotube network. We have fabricated TiO(2)-based dye-sensitized fiber solar cells with a Pt-nanotube hybrid yarn as counter electrode and achieved a power conversion efficiency of 4.85% under standard illumination (AM1.5, 100 mW/cm(2)), comparable to the same type of fiber cells with a Pt wire electrode (4.23%). Adsorption of Pt nanoparticles within a porous nanotube yarn results in enhanced Pt-electrolyte interfacial area and significantly reduced charge-transfer resistance across the electrolyte interface, compared to a pure nanotube yarn or Pt wire. Our porous Pt-nanotube hybrid yarns have the potential to reduce the use of noble metals, lower the device weight, and improve the solar cell efficiency.

No abstract

Tandem cells are solar cells made of multiple junctions with tunable absorbing materials, which aim to overcome the Shockley–Queisser limit of single junction solar cells. Recently, organic–inorganic hybrid perovskite solar cells have stirred enormous interest as ideal candidates for tandem cells, due to high open circuit voltage, relatively wide optical bandgap, and low temperature solution processibility. So far, a great number of review papers have been focused on the development of a single junction, in the context of the investigation of operational principles, the materials growth/understanding, and interface engineering. Here, we have provided a summary of the recent developments in the realization and understanding of perovskite‐based tandem cells. The optical simulations for the design of perovskite‐based tandem cells are first presented in order to optimize the device architecture in theoretical perspective. Then, an overview of the recent progress in silicon–perovskite, perovskite–perovskite, and others–perovskite tandem cells is highlighted. Specifically, we will focus on the key issues for high efficiency tandem cells, e.g., transparent electrodes, intermediate layers, and bandgap engineering. Suggestions with respect to the further improvement toward perovskite tandem optoelectronics are discussed based on the available literature.

A composite (Ag-g-CNQDs) was prepared from graphitic carbon nitride quantum dots and silver nanoparticles by water phase synthesis. Aided by metal-enhanced fluorescence, the composite exhibits excitation-dependent red emission with a peak at 600 nm with a quantum yield of 21%. If the composite is coated with polyethylenimine (PEI) to form the Ag-g-CNQD/PEI complexe, fluorescence is strongly reduced. Upon addition of heparin, the fluorescence of the system is enhanced because PEI has a higher affinity for heparin than Ag-g-CNQDs. The effect was used to design a fluorometric  assay for heparin. The emission at 600 nm increases linearly in the 0.025 to 2.5 μM heparin concentration range, with a 8.2 nM limit of detection. Graphical abstract Schematic illustration for fabricating a composite consisting of silver nanoparticles and graphitic carbon nitride quantum dots (Ag-g-CNQDs). Its red fluorescence is weak in presence of polyethyleneimine but restored on addition of heparin. This forms the basis for a new method for heparin detection.