Herein, we present the synthesis of CsPbBr 3 quantum dots (QDs) by a ligand-assisted reprecipitation (LARP) technique under an ambient atmosphere. Besides, the optoelectronic properties of CsPbBr 3 QDs were improved through antimony tribromide (SbBr 3 ) post-treatment. Photoluminescence quantum yield (PLQY) was enhanced from 72 to 89% for SbBr 3 post-treated QDs compared to as-synthesized QDs. High-resolution transmission electron microscopy (HR-TEM) analysis shows the formation of uniform-size CsPbBr 3 QDs (9.4 ± 1.3 nm) after SbBr 3 treatment. The X-ray diffraction (XRD) pattern confirms the presence of the cubic phase of CsPbBr 3 QDs before and post-treatment. Moreover, temperature-dependent PL and X-ray photoelectron spectroscopy (XPS) characterizations confirm the effective defect passivation with SbBr 3 post-treatment. The timeresolved PL lifetime of CsPbBr 3 QDs was enhanced from 24.80 ± 0.10 to 37.71 ± 0.09 ns after post-treatment. Finally, the posttreated QD-based self-powered photodetector device showed a high responsivity of 48.1 μA/W compared to the as-synthesized QD device's responsivity of 10.2 μA/W.

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An exponential dependence of conductance on thickness and temperature was found in the low-voltage, Ohmic regime of copper (CuPc) and cobalt (CoPc) phthalocyanine, sandwiched between palladium and gold electrodes unlike ever claimed in organic materials. To assure cleanliness and integrity of the electrode-phthalocyanine interface, the devices were prepared in situ, using organic molecular beam deposition with a floating shadow mask. The dc transport measurements in a wide temperature and thickness range show that (i) the low-voltage J-V curve is linear, with current increasing sharply at higher voltages, (ii) the low-voltage conductance increases exponentially with temperature, and (iii) it decreases exponentially with film thickness. A comparison with conventional models fails to explain all the data with a single set of parameters. On the other hand, a model outlined here, which incorporates tunneling between localized states with thermally induced overlap, agrees with the data and decouples the contributions to conductance from the electrode-film interface and the bulk of the film.

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Carbon nanotubes (CNTs) were synthesized by Chemical Vapor Deposition (CVD) from the pyrolytic decomposition of Iron Phthalocyanine (FePc) molecules, on SiO2/Si(111) substrates in the presence of a hydrogen flow. FePc molecules contribute simultaneously both to the formation of the precursor Fe nanoparticles and also as a Carbon source. Different experimental conditions were examined. Samples were characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and inverse photoemission. The resulting samples are highly oriented multiwall carbon nanotubes films, with heights in the range between: 4 and 20 microm. The tubes diameter is strongly dependent on growth temperature. Our experimental results show evidence of a transition in the growth mechanism, from a tip growth to a base growth mode, as the decomposition temperature is increased. Preliminary spectroscopic measurements performed on these MWCNTs, show the unoccupied density of states has several resonances close to Fermi level, related both to the graphene electronic structure and the formation of the tube.

Hybrid nanostructured arrays based on carbon nanotubes (CNT) and palladium or titanium dioxide materials have been synthesized using self-supported and silicon-supported anodized aluminum oxide (AAO) as nanoporous template. It is well demonstrated that carbon nanotubes can be grown using these membranes and hydrocarbon precursors that decompose at temperatures closer to 600°C without the use of a metal catalyst. In this process, carbonic fragments condensate to form stacked graphitic sheets, which adopt the shape of the pores, yielding from these moulds' multi-walled carbon nanotubes. After this process, the ends of the tubes remain open and accessible to other substances, whereas the outer walls are protected by the alumina. Taking advantage of this fact, we have performed the synthesis of palladium and titanium dioxide nanostructures selectively inside carbon nanotubes using these CNT-AAO membranes as nanoreactors.

Carbon nanostructures were synthesized by decomposition of different carbon sources over an alumina supported palladium catalyst via Chemical Vapor Deposition (CVD). Several experimental conditions were varied to verify their influence in the synthesis products: temperature ramping rate, pre-annealing conditions, hydrogen pre-treatment, synthesis temperature and time, together with the use of different carbon sources. Depending on the experimental conditions carbon nanotubes and nanofibers with different shapes and structural characteristics were obtained. Straight, coiled and branched morphologies are the most common. Among our findings, the addition of hydrogen plays a significant role in the structure of the carbonaceous products. For example, the decomposition of acetylene on palladium catalysts at 800 degrees C in the absence of hydrogen produces only carbon micro- spheres as synthesis products. The incorporation of increasing amounts of hydrogen modifies the outcome, from thick fibers to carbon nanotubes. To verify the level of graphitization of the synthesis products we have used high resolution transmission electron microscopy (HRTEM) in addition to Raman spectroscopy. Our results, based on these complementary techniques, indicate the decomposition of acetylene on a palladium based catalyst, produces the best degree of graphitization in carbon nanotubes for a temperature of 800 degrees C and 100 cc/min of hydrogen flow. Similar hydrogen flows on the same catalyst, produced highly graphitized nanofibers by the decomposition of methane at 850 degrees C.