Endohedral metallofullerenes have a electric dipole moment due to the exchange of electrons between the encapsulated metal atom and a fullerene cage. To realize molecular orientation switching device by using endohedral metallofullerene, it needs to clarify the switching mechanism. Here, we demonstrate molecular resolution scanning tunneling microscopy (STM) image and current imaging tunneling spectroscopy (CITS) of Lu@C_<82> on octanthtiol self assembled monolayer (SAM) before and after applying sample voltage, and compare these STM images and CITS with density functional theory (DFT) calculation of Lu@C_<82>. We demonstrate change in the molecular orientation of Lu@C_<82>.
In this work, we demonstrate a novel dopamine sensor using multimode surface plasmon excitations by irradiating white light source on metallic diffraction gratings/plastic substrates. Since the grating pitch is larger than commonly used diffraction gratings, multiple surface plasmon resonance excitations due to several diffraction orders were observed at same time. Layer-by-layer ultrathin films prepared from iron containing bis (terpyridine) polymer (Fe(II)-BTP) and poly (ethylene dioxythiophene): poly (styrene sulfonate) (PEDOT: PSS) were used as an electrochemical mediator for sensing the dopamine. Large changes in grating coupling surface plasmon dips were obtained upon an injection of the dopamine on the LbL/metallic grating surface.
Due to recent demands of improving the contrast and brightness in LC projection displays, the vertical alignment display mode with inorganic alignment films has been gradually used in the projection displays. In this study, we mainly focus on the vertical LC alignment control on inorganic films for LC projection displays. Two types of inorganic films of SiOx and F-DLC, which are respectively deposited with a reactive RF sputtering method and a PBII & D method, are characterized using various methods. From the study, we clarify the advantage and disadvantage of using the two inorganic films as vertical alignment layers of LCs
We have fabricated the photovoltaic devices consisting of ITO/hole extraction layer/H_2TPP/C_<60>/BCP/Al structures. Open circuit voltage (V_<OC>) markedly increased when H_2TPP was used as p-type semiconductor instead of copper pthalocyanine. Both fill factor and V_<OC> further increased with the insertion of NiO or MoO_3 layer due to the increment of built-in potential. However, photovoltaic properties of the device with MoO_3 was markedly degraded by heat-treatment. It was ascribed to the change of work-function of MoO_3 and the electric field at H_2TPP/MoO_3 interface by surface potential measurement.
Temperature dependence of electron and hole mobility were investigated for (BEDT-TTF) (TCNQ) crystalline field effect transistors. The field-effect electron and hole mobility abruptly increased at 280K, which will due to a phase transition occuring at the channel region of the field-effect transistor. In addition, ferroelectricity-like behavior was observed below 280K.
It has been taken for granted that molecules in organic vacuum-deposited amorphous films are randomly oriented and the films themselves are isotropic. Here, however, the authors demonstrate horizontal orientation of long or planar molecules in organic amorphous films using variable angle spectroscopic ellipsometry and cutoff emission measurement. The molecular orientation was observed in films on many kinds of underlying layers and even in doped films. It was found that there is a correlation between molecular structures and orientation order parameters and that the orientation affects electrical characteristics of the films. The horizontal molecular orientation can be utilized to improve light out-coupling efficiencies and carrier transport characteristics of OLEDs.
The theoretical equations for I-V characteristics in an organic semiconductor was derived according to the internal carrier emission equation based on a diffusion model at Schottky barrier contact and the mobility equation based on the Pool-Frenkel model. The validity of this equation was confirmed by comparing with the results from the device simulation where the same models and parameters were employed. When the barrier height is high enough, the electric field get to be constant because of no space-charge effect, but the field distribution has to be considered in case of low barrier height. There is, however, no zero-field region even in case of extremely low barrier height, which suggests the difference from the ordinal space-charge limited current.