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We have fabricated highly efficient CdS/CdSe quantum dot-sensitized solar cells (QDSSCs) featuring low-cost cobalt sulfide (CoS) counter electrodes. Under 100 mW cm(-2) irradiation, the CdS/CdSe QDSSC featuring a CoS electrode provided an energy conversion efficiency as high as 3.4%.

Aggregation löscht Fluoreszenz: Mit 11‐Mercaptoundecansäure (11‐MUA) geschützte Goldnanopartikel (11‐MUA‐AuNPs) sind deutlich beständiger und fluoreszieren viel stärker als die nichtmodifizierten AuNPs. Nach der Zugabe von 2,6‐Pyridindicarbonsäure binden die 11‐MUA‐AuNPs hoch empfindlich und selektiv an HgII‐Ionen, die eine Aggregation induzieren, die zur Fluoreszenzlöschung führt.

We report a simple synthesis of Au-Ag core-shell nanorods (NRs) under alkaline conditions (pH 8.0-10.0) from silver and ascorbate ions using gold nanorods (GNRs) as the seeds. The silver ions that are reduced by the ascorbate ions become deposited on the surfaces of the GNRs to form differently dumbbell-shaped Au-Ag core-shell NRs and nanoparticles, depending on the pH and the concentration of silver ions. The longitudinal plasmon absorbance bands of the Au-Ag core-shell NRs are stronger and appear at shorter wavelengths than those for the original GNRs. We confirmed the formation of Au-Ag core-shell NRs by both energy-dispersive X-ray spectrometry and inductively coupled plasma mass spectrometry measurements, which indicate that the 109Ag/197Au ratios are 0.046, 0.085, and 0.097 at pH 8.0, 9.0, and 10.0, respectively. The transmission electron microscopy measurements show that the Au-Ag core-shell NRs are monodispersed (>90%).

The water-immiscible ionic liquid, [C4MIM][PF6], is a solvent medium that allows complete transfer of gold nanoparticles from an aqueous phase into an organic phase. Both spherical and rod-shaped gold nanoparticles are efficiently transferred from an aqueous solution into the organic phase without requiring the use of thiols. The sizes and shapes of the gold nanoparticles were preserved during the phase-transfer process when a surfactant was added to the ionic liquid. This process offers a simple approach for obtaining solutions of differently sized and shaped gold nanoparticles in ionic liquids.

We have demonstrated a simple approach to the synthesis of fluorescent trigonal tellurium (t-Te) nanowires in aqueous solution at room temperature. The t-Te nanowires were prepared from the reduction of tellurium dioxide (TeO 2 ) with concentrated hydrazine solution through deposition of Te atoms that were reduced from telluride ions (Te 2-) and dissolved from amorphous tellurium (a-Te) nanoparticles onto t-Te nanocrystallines. By carefully controlling the growth time from 40 to 120 min, we prepared different sizes of t-Te nanowires; the length changed from 251 to 879 nm, while the diameter only grew from 8 to 19 nm. The absorption wavelength against the diameter of t-Te nanowires displays the diameter dependence of band I (<300 nm). On the other hand, the absorption wavelength against the length of t-Te nanowires displays the length dependence of band II (>600 nm). By increasing the size of t-Te nanowires, their absorption is under a red shift. For example, the maximum wavelengths of the absorption bands for the t-Te nanowires with the lengths of 251 nm are 271 and 602 nm, while those for 879 nm t-Te nanowires are at 280 and 687 nm, respectively. Deconvolution of the photoluminescence profile for t-Te nanowires obtained at 120 min yields four Gaussian peaks centered at 334, 397, 460, and 507 nm.

Quantum dot-sensitized solar cells (QDSSCs) are interesting energy devices because of their (i) impressive ability to harvest sunlight and generate multiple electron/hole pairs, (ii) ease of fabrication, and (iii) low cost. The power conversion efficiencies (η) of most QDSSCs (typically <4%) are, however, less than those (up to 12%) of dye-sensitized solar cells, mainly because of narrow absorption ranges and charge recombination occurring at the QD-electrolyte and TiO(2)-electrolyte interfaces. To further increase the values of η of QDSSCs, it will be necessary to develop new types of working electrodes, sensitizers, counter electrodes and electrolytes. This Feature Article describes the nanomaterials that have been used recently as electronic conductors, sensitizers and counter electrodes in QDSSCs. The nature, size, morphology and quantity of these nanomaterials all play important roles affecting the efficiencies of electron injection and light harvesting. We discuss the behavior of several important types of semiconductor nanomaterials (sensitizers, including CdS, Ag(2)S, CdSe, CdTe, CdHgTe, InAs and PbS) and nanomaterials (notably TiO(2), ZnO and carbon-based species) that have been developed to improve the electron transport efficiency of QDSSCs. We point out the preparation of new generations of nanomaterials for QDSSCs and the types of electrolytes, particularly iodide/triiodide electrolytes (I(-)/I(3)(-)), polysulfide electrolytes (S(2-)/S(x)(2-)), and cobalt redox couples ([Co(o-phen)(3)(2+)/(3+)]), that improve their lifetimes. With advances in nanotechnology, we foresee significant improvements in the efficiency (η > 6%) and durability (>3000 h) of QDSSCs.