Structures, fundamental properties, and potential applications of low-dimensional C polymers and other nanocarbons: a review.

Since carbon (C) atom has a variety of chemical bonds hybridization between s and p atomic orbitals, it is well known that there are robust carbon materials. In particular, discovery of C has been an epoch making to cultivate nanocarbon fields. Since then, nanocarbon materials such as nanotube and graphene have been reported.

Micro-/macroscopic and density functional studies of the interactions between molybdenum trioxide and C molecule.

We have investigated the interactions between C and (MoO) using scanning tunneling microscopy with spectroscopy (STM/STS) and ex situ ultraviolet-visible-near-infrared (UV-vis-NIR) spectroscopy in combination with density functional theory (DFT) calculations. The formation of (MoO) chemically bound to C is energetically favorable due to ΔG < 0 for n = 1, 2, 4, 6, 8, and 9, and they well reproduced the histogram of the height of (MoO) on the C (111) terrace obtained by a STM height-profile. STS results demonstrated the upward energy shift of both highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of C in the vicinity of (MoO) (n = 6 or 9), which is consistent with the previous results of the co-deposited C/MoO film obtained using photoemission and inverse photoemission spectroscopy [Wang and Gao, Appl.

Unraveling the reasons behind lead phthalocyanine acting as a good absorber for near-infrared sensitive devices.

Lead phthalocyanine (PbPc) is well known to be used as a good near-infrared (NIR) light absorber for organic solar cells (OSCs) and photodetectors. The monoclinic and triclinic phases have been understood to absorb the visible and NIR regions, respectively, so far. In the present study, we demonstrated from the absorption spectra and theoretical analysis that the visible band considerably originates from not only the monoclinic but also the amorphous and triclinic phases, and revealed the exciton dynamics in the PbPc film from static/time-resolved photoluminescence (PL), which are first reported.

The uptake mechanism of palladium ions into Prussian-blue nanoparticles in a nitric acid solution toward application for the recycling of precious metals from electronic and nuclear wastes.

We have investigated the uptake mechanism of palladium (Pd: one of the most important elements in industry used as a catalyst) ions into Prussian-blue nanoparticles (PBNPs) in a nitric acid solution high-resolution electron transmission microscopy, inductively coupled plasma atomic emission spectroscopy, powder X-ray diffraction, and ultraviolet-visible-near infrared spectroscopy in combination with first principles calculations. Comparison of the structural and electronic properties of PBNPs between before and after a 24 h sorption test reveals that the Pd ions incorporated into PBNPs by the substitution of Fe ions of the PB framework while maintaining the crystal structure, and the substitution efficiency is estimated to be 87% per PB unit cell. This implies that 0.

The uptake characteristics of Prussian-blue nanoparticles for rare metal ions for recycling of precious metals from nuclear and electronic wastes.

We have examined the uptake mechanisms of platinum-group-metals (PGMs) and molybdenum (Mo) ions into Prussian blue nanoparticles (PBNPs) in a nitric acid solution for 24-h sorption test, using inductively coupled plasma atomic emission spectroscopy, powder XRD, and UV-Vis-NIR spectroscopy in combination with first-principles calculations, and revealed that the Ru and Pd ions are incorporated into PBNPs by substitution with Fe and Fe ions of the PB framework, respectively, whereas the Rh ion is incorporated into PBNPs by substitution mainly with Fe and minorly with Fe ion, and Mo ion is incorporated into PBNPs by substitution with both Fe and Fe ions, with maintaining the crystal structure before and after the sorption test. Assuming that the amount of Fe elusion is equal to that of PGMs/Mo substitution, the substitution efficiency is estimated to be 39.0% for Ru, 47.

Thermally Stable Array of Discrete Cs on a Two-Dimensional Crystalline Adlayer of Macrocycles both in Vacuo and under Ambient Pressure.

A periodic monolayer array of discrete Cs was generated on an atomically flat Au(111) surface with the aid of a template adlayer. The template was a two-dimensional (2D) array of molecular pits prepared on an Au(111) surface through 2D crystallization of shape-persistent macrocycles composed of four carbazole and four salphens/Ni-salphens with a 1 nm hollow. Scanning tunneling microscopy imaging under ultra-high vacuum revealed that the square-shaped macrocycles, with 1.

Resolving Site-Specific Energy Levels of Small-Molecule Donor-Acceptor Heterostructures Close to Metal Contacts.

The active material of optoelectronic devices must accommodate for contacts which serve to collect or inject the charge carriers. It is the purpose of this work to find out to which extent properties of organic optoelectronic layers change close to metal contacts compared to known properties of bulk materials. Bottom-up fabrication capabilities of model interfaces under ultrahigh vacuum and single-atom low temperature (LT)-STM spectroscopy with density functional theory (DFT) calculations are used to detect the spatial modifications of electronic states such as frontier-orbitals at interfaces.

Morphological and optical properties of α- and β-phase zinc (∥) phthalocyanine thin films for application to organic photovoltaic cells.

We have investigated the morphological and optical properties of α- and β-phase Zinc Phthalocyanine (ZnPc) thin films for application to organic photovoltaic cells (OPVs). It was found that the α-phase is completely converted to the β-phase by thermal annealing at 220 °C under ultrahigh vacuum conditions. When the α- to β-phase transition takes place, the surface roughness of the ZnPc film became flat uniformly with a nanometer order of unevenness by anisotropic growth of crystalline grains along a lateral direction to substrates.

Low thermal conductivity of peanut-shaped carbon nanotube and its insensitive response to uniaxial strain.

Motivated by the experimental synthesis of peanut-shaped carbon nanotubes (PSNTs) that combine the novel features of fullerene and carbon nanotubes (CNTs), we study the thermal conductivity of a PSNT (1dp08) and its response to different strains by using non-equilibrium molecular dynamics simulations and lattice dynamics together with density functional theory. We find that the thermal conductivity of the PSNT is reduced by more than 90% as compared to that of CNTs, and remains almost the same when different strains applied, exhibiting very different behaviors from that of CNTs, where the thermal conductivity decreases monotonically with the increase of strain. Through phonon mode calculations, we show that the reduced phonon group velocity, phonon lifetime and the vibrational mismatch are responsible for the low thermal conductivity of the PSNT, and the insensitive response of thermal conductivity to strain is due to the insensitivity of its phonon density of states and group velocity to strain.

Spectroscopic and theoretical studies on the structural, electronic, and optical properties of zinc octaethylporphyrin/C co-deposited films.

We have examined the structural, electronic, and optical properties of zinc-octaethylporphyrin [Zn(OEP)]/C co-deposited films to elucidate the donor (D)-acceptor (A) interactions at the D/A interface of heterojunction organic solar cells (OSCs), using Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), ultraviolet-visible (UV-vis) spectroscopy, and photoluminescence (PL) spectroscopy in combination with first-principles and semi-empirical calculations. The FT-IR and XRD results indicated that Zn(OEP) and C were mixed with each other at the molecular level in the co-deposited film. The theoretical calculations suggested that in the interfacial region, it is energetically preferable for the C molecule to face the center of the planar structure of Zn(OEP) at a distance of 2.

Columnar Liquid Crystals from a Giant Macrocycle Mesogen.

Columnar liquid crystals composed of a giant macrocyclic mesogen were prepared. The giant macrocyclic mesogen has a square hollow with a 2.5 nm diagonal, which was bounded by diindolo[3,2-b:2',3'-h]carbazole (diindolocarbazole) moieties as the edges and bis(salicylidene)-o-phenylenediamine (salphen) moieties as the corners.

Basic aspects for improving the energy conversion efficiency of hetero-junction organic photovoltaic cells.

Hetero-junction organic photovoltaic (OPV) cells consisting of donor (D) and acceptor (A) layers have been regarded as next-generation PV cells, because of their fascinating advantages, such as lightweight, low fabrication cost, resource free, and flexibility, when compared to those of conventional PV cells based on silicon and semiconductor compounds. However, the power conversion efficiency (η) of the OPV cells has been still around 8%, though more than 10% efficiency has been required for their practical use. To fully optimize these OPV cells, it is necessary that the low mobility of carriers/excitons in the OPV cells and the open circuit voltage (V OC), of which origin has not been understood well, should be improved.

Dimensional dependence of electronic structure of fullerene polymers.

Fullerene polymers made of C(60) are systematically investigated by means of a first-principles pseudopotential approach within the local density approximation of the density functional theory. We assume 10 different structures of fullerene polymers. The first three are C(60) polymer networks cross-linked by [2+2] cycloadditional four-membered rings, and the other seven are composed of peanut-shaped fused C(60) polymer chains cross-linked by either seven-membered rings or eight-membered rings.

In situ x-ray photoelectron spectroscopic and density-functional studies of Si atoms adsorbed on a C60 film.

The interaction between C(60) and Si atoms has been investigated for Si atoms adsorbed on a C(60) film using in situ x-ray photoelectron spectroscopy (XPS) and density-functional (DFT) calculations. Analysis of the Si 2p core peak identified three kinds of Si atoms adsorbed on the film: silicon suboxides (SiO(x)), bulk Si crystal, and silicon atoms bound to C(60). Based on the atomic percent ratio of silicon to carbon, we estimated that there was approximately one Si atom bound to each C(60) molecule.