R. Gaal

Nanowires of Methylammonium Lead Iodide (CH3NH3PbI3) Prepared by Low Temperature Solution-Mediated Crystallization

We report the synthesis of Methylammonium Lead Iodide (CH(3)NH(3)PbI(3)) nanowires by a low temperature solution processed crystallization using a simple slip-coating method. The anisotropic particle shape exhibits advantages over nanoparticles in terms of charge transport under illumination. These results provide a basis for solvent-mediated tailoring of structural properties like the crystallite size and orientation in trihalide perovskite thin films, which, once implemented into a device, may ultimately result in an enhanced charge carrier extraction.

Microengineered CH3NH3PbI3 Nanowire/Graphene Phototransistor for Low‐Intensity Light Detection at Room Temperature

The first hybrid phototransistors are reported where the performance of a network of photoactive CH3NH3PbI3 nanowires is enhanced by CVD-grown monolayer graphene. These devices show responsivities as high as ≈2.6 × 106 A W-1 in the visible range, showing potential as room-temperature single-electron detectors.

Effect of electron irradiation on the electrical properties of fibers of aligned single-walled carbon nanotubes

We carried out in situ resistivity measurements on macroscopic oriented ropes of single wall carbon nanotubes in a transmission electron microscope. We have found a minimum in the resistivity as a function of irradiation dose. This minimum is interpreted as a result of a twofold effect of the irradiation: the domination of covalent bond formation between tubes in a bundle due to broken bonds in the tube walls and the amorphization of the sample at high dose. Despite this improvement, the temperature dependence of the resistivity remains hopping-like.

Synthesis and manipulation of carbon nanotubes

{\mathrm{Cd}}_{2}{\mathrm{Os}}_{2}{\mathrm{O}}_{7}

Field emission properties of carbon nanohorn films

crystallizes in the pyrochlore structure and undergoes a metal-insulator transition (MIT) near 226 K. We have characterized the MIT in

Continuous-wave far-infrared ESR spectrometer for high-pressure measurements

{\mathrm{Cd}}_{2}{\mathrm{Os}}_{2}{\mathrm{O}}_{7}

Pressure dependence of the large-polaron transport in anatase TiO2 single crystals

using x-ray diffraction, resistivity at ambient and high pressure, specific heat, magnetization, thermopower, Hall coefficient, and thermal conductivity. Both single crystals and polycrystalline material were examined. The MIT is accompanied by no change in crystal symmetry and a change in unit-cell volume of less than 0.05%. The resistivity shows little temperature dependence above 226 K, but increases by 3 orders of magnitude as the sample is cooled to 4 K. The specific heat anomaly resembles a mean-field transition and shows no hysteresis or latent heat.

Electronic and Mechanical Properties of Carbon Nanotubes

{\mathrm{Cd}}_{2}{\mathrm{Os}}_{2}{\mathrm{O}}_{7}

Microwave frequency modulation in continuous-wave far-infrared ESR utilizing a quasi-optical reflection bridge

orders magnetically at the MIT. The magnetization data are consistent with antiferromagnetic order, with a small parasitic ferromagnetic component. The Hall and Seebeck coefficients are consistent with a semiconducting gap opening at the Fermi energy at the MIT. We have also performed electronic structure calculations on