Quantum dots(QDs) with their tunable luminescence properties are uniquely suited for use as lumophores in light emitting device. We investigate the microstructural effect on the electroluminescence(EL). Here we report the use of inorganic semiconductors as robust charge transport layers, and demonstrate devices with light emission. We chose mechanically smooth and compositionally amorphous films to prevent electrical shorts. We grew semiconducting oxide films with low free-carrier concentrations to minimize quenching of the QD EL. The hole transport layer(HTL) and electron transport layer(ETL) were chosen to have carrier concentrations and energy-band offsets similar to the QDs so that electron and hole injection into the QD layer was balanced. For the ETL and the HTL, we selected a 40-nm-thick ZnSnOx with a resistivity of 10Ω·cm, which show bright and uniform emission at a 10 V applied bias. Light emitting uniformity was improved by reducing the rpm of QD spin coating.At a QD concentration of 15.0 mg/mL, we observed bright and uniform electroluminescence at a 12 V applied bias. The significant decrease in QD luminescence can be attributed to the non-uniform QD layers. This suggests that we should control the interface between QD layers and charge transport layers to improve the electroluminescence.

In this work, fabrication and electrochemical analysis of an individual multi-walled carbon nanotube (MWNT) electrode are carried out to confirm the applicability of electrochemical sensing. The reactive ion etching (RIE) process is performed to obtain sensitive MWNT electrodes. In order to characterize the electrochemical properties, an individual MWNT is cut by RIE under oxygen atmosphere into two segments with a small gap: one segment is applied to the working electrode and the other is used as a counter electrode. Electrical contacts are provided by nanolithography to the two MWNT electrodes. Dopamine is specially selected as an analytical molecule for electrochemical detection using the MWNT electrode. Using a quasi-Ag/AgCl reference electrode, which was fabricated by us, the nanoelectrodes are subjected to cyclic voltammetry inside a 2μL droplet of dopamine solution. In the experiment, RIE power is found to be a more effective parameter to cut an individual MWNT and to generate "broken" open state, which shows good electrochemical performance, at the end of the MWNT segments. It is found that the pico-molar level concentration of analytical molecules can be determined by an MWNT electrode. We believe that the MWNT electrode fabricated and treated by RIE has the potential for use in high-sensitivity electrochemical measurement and that the proposed scheme can contribute to device miniaturization.

Lithium dihydrogen phosphate (LiH2PO4) powder was purchased from Aldrich Chemical Co. Fromthe scanning electron microscope (SEM) observation, these polycrystals have dimensions in the range of 25-250µm. The electrical conductivity was measured at a measuring frequency of 1 kHz on heating polycrystallinelithium dihydrogen phosphate (LiH2PO4) from room temperature to 493 K. Two anomalies appeared at 451K (Tp1) and 469 K (Tp2). The electrical conductivity reached the magnitude of the superprotonic phases: 3×10-2Ω-1cm-1 at 451 K (Tp1) and 1.2×10Ω-1cm-1 at 469 K (Tp2). It is uncertain whether the superprotonic phasetransformations are due to polymorphic transitions in the bulk, surface transitions, or chemical reactions(thermal decomposition) at the surface. Considering several previous thermal studies (differential scanningcalorimetry and thermogravimetry), our experimental results seem to be related to the last case: chemicalreactions (thermal decomposition) at the surface with the progressive solid-state polymerization.

Multi-walled carbon nanotubes (MWNTs) were synthesized on different substrates (bare Si and SiO2/Si substrate) to investigate dye-sensitized solar cell (DSSC) applications as counter electrode materials. The synthesis of MWNTs samples used identical conditions of a Fe catalyst created by thermal chemical vapor deposition at 900˚C. It was found that the diameter of the MWNTs on the Si substrate sample is approximately 5~10nm larger than that of a SiO2/Si substrate sample. Moreover, MWNTs on a Si substrate sample were well-crystallized in terms of their Raman spectrum. In addition, the MWNTs on Si substrate sample show an enhanced redox reaction, as observed through a smaller interface resistance and faster reaction rates in the EIS spectrum. The results show that DSSCs with a MWNT counter electrode on a bare Si substrate sample demonstrate energy conversion efficiency in excess of 1.4 %.