Lithium‐Ion Endohedral Fullerene (Li+@C60) Dopants in Stable Perovskite Solar Cells Induce Instant Doping and Anti‐Oxidation

Herein, we report use of [Li⁺@C₆₀]TFSI^? as a dopant for spiro‐MeOTAD in lead halide perovskite solar cells. This approach gave an air stability nearly 10‐fold that of conventional devices using Li⁺TFSI^?. Such high stability is attributed to the hydrophobic nature of [Li⁺@C₆₀]TFSI^? repelling moisture and absorbing intruding oxygen, thereby protecting the perovskite device from degradation. Furthermore, [Li⁺@C₆₀]TFSI^? could oxidize spiro‐MeOTAD without the need for oxygen. The encapsulated devices exhibited outstanding air stability for more than 1000 h while illuminated under ambient conditions.     

Studies of degradation behaviors of poly (3‐hexylthiophene) layers by X‐ray photoelectron spectroscopy

Degradation behaviors of poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) layers on NiO in the presence of H₂O at ambient pressure and dark conditions were studied using X‐ray photoelectron spectroscopy (XPS). Upon H₂O exposure at 120 °C, partial oxidation of P3HT together with molecular water incorporation, but with the maintained local ring‐structure, were deduced by XPS. Valence band spectra of XPS evidenced that the partial oxidation of P3HT local structure could alter π‐conjugation systems of P3HT layers, forming additional electronic states close to its original highest occupied molecular orbital. For comparison, P3HT surface was also exposed to O₂, and no change in the S 2p and C 1s spectra was found by O₂ exposure at 120 °C, implying that H₂O plays a major role at the initial stage of P3HT oxidation. Copyright © 2014 John Wiley & Sons, Ltd.     

Effect of Thermal Treatment on Preshaped Ionic Polymer Metal Composite (IPMC) Actuators

A new method to fabricate ionic polymer metal composite (IPMC) actuators with a 3-dimensional preshaped form by a simple thermal treatment process is demonstrated. The effects of the thermal treatment process on the properties of the actuator are analyzed and the characteristics of the actuator, such as stiffness, displacement and resonance, generating force, and repeated motions, are compared with those of unheated IPMC actuators. The experimental results show that thermal-treated IPMC actuators have improved generating force as well as preshaping of the 3-dimensional form.     

Metrological orientation-confirmation of Si(h h k) using scanning tunneling microscopy

For the periodicity-modulation of the Si(h h k) template between (0 0 1) and (1 1 1), it is necessary to prepare the surface with any orientation within this range, most especially for fabricating useful one-dimensional nanostructures. Especially, when there are no strong X-ray signals using the standard Cu K-α source in the vicinity of any arbitrarily chosen (H H K), it turns out that the line-profile analysis on the topographic image of scanning tunneling microscopy can be a unique way for confirming the orientation of the prepared surface. Though there are a number of small-width facets on the reconstructed surface, if any of well-defined facets, such as (1 1 1), (3 3 7), (1 1 2), and (3 3 5), are included in these facets it is possible to determine the orientation using the weighted-average method.     

Performance studies of a full-length prototype for the CASTOR forward calorimeter at the CMS experiment

The Time-Of-Flight detector (TOF) of the ALICE experiment at the CERN LHC is based on Multi-gap Resistive Plate Chambers (MRPCs). The TOF detector consists of 152928 readout channels covering a total area of 141 m². In this paper the results of the calibration with cosmic-ray data collected during 2009 are presented.     

Spectroscopic investigation on the electronic structure of a 5d band insulator SrHfO3 in proximity to ferroelectric instability: Comparison with SrTiO3 and SrZrO3

We investigated the high-energy electronic structure of a 5d perovskite SrHfO₃ by using optical spectroscopy and O 1s x-ray absorption spectroscopy. From the combined spectra the values of electronic structure parameters are estimated properly. In particular, the crystal field splitting energy, which is closely associated with the p–d hybridization strength, is as high as ～5 eV, and the Sr 4d bands appear to be strongly mixed with the Hf 5d bands. These findings are discussed in relation to a possible ferroelectric instability in SrHfO₃, and are compared with electronic properties of similar compounds, 3d SrTiO₃ and 4d SrZrO₃.     

Spectroscopic investigations of 1.06 μm emission in Nd-doped alkali niobium zinc tellurite glasses

Thermal, structural and optical properties of Nd³⁺ ions in tellurite glass (TeO₂-ZnO-Na₂O-Li₂O-Nb₂O₅) have been investigated. Differential thermal analysis revealed reasonably good forming tendency of the glass composition. FTIR spectra were used to analyze the functional groups present in the glass. Judd-Ofelt intensity parameters were derived from the absorption spectrum and used to calculate the radiative lifetime, branching ratio and stimulated emission cross-section of the ⁴F_3/2→⁴I_9/2, _{11/2, 13/2} transitions. The quantum efficiency of the ⁴F_3/2 level is comparable as well as higher than the typical value of the other tellurite based glasses. The decay from the ⁴F_3/2 level is found to be single exponential for different concentrations of Nd³⁺ ions with a shortening of lifetime with increasing concentration. The experimental values of branching ratio and saturation intensity of ⁴F_3/2→⁴I_11/2 transition indicate the favourable lasing action with low threshold power.