A novel thiophene‐thienylenevinylene copolymer is synthesized and evaluated for use in organic field‐effect transistors and organic solar cells. PETV12T shows good solution processability and high structural organization after annealing. Organic thin‐film transistors based on the polymer exhibit high mobility and a high resistance to oxidation. In addition, PETV12T shows potential as an electron donor in bulk heterojunction solar cells.

We present a high speed optical modulation using carrier depletion effect in an asymmetric silicon p-n diode resonator. To optimize coupling efficiency and reduce bending loss, two-step-etched waveguide is used in the racetrack resonator with a directional coupler. The quality factor of the resonator with a circumference of 260 um is 9,482, and the DC on/off ratio is 8 dB at -12V. The device shows the 3dB bandwidth of approximately8 GHz and the data transmission up to 12.5Gbit/s.

The CO2-, CH4-, and CO2/CH4-loaded β-form hydroquinone (HQ) clathrates were synthesized by the gas-phase reaction between α-form HQ and high pressure gases. Temperature-dependent Raman spectra of guest-free, CO2-loaded, CH4-loaded, and CO2/CH4-loaded β-form HQ clathrates were measured in the temperature range 300–385 K at increments of 5 K. The CH4 molecules rapidly escaped from the β-form HQ clathrate in the temperature range 360–380 K, whereas the CO2 molecules were gradually released from the β-form HQ clathrate framework in the wide temperature range 300–380 K. It was also found that both CO2 and CH4 molecules were rapidly released from the CO2/CH4-loaded β-form HQ clathrate framework in the temperature range 360–380 K. However, all of the guest-free and guest-loaded β-form HQ clathrates were fully converted to the α-form HQ at the same temperature of 385 K. These results demonstrate the strong effect of temperature on both guest–host interactions and the stability of the framework structure.

The crystallization behavior of nitrogen-doped amorphous Ge 2 Sb 2 Te 5 -(N) phase-change thin films was studied by utilizing differential scanning calorimetry, in situ ellipsometry and in situ transmission electron microscopy. The combined analysis of in situ ellipsometry isotherms of amorphous Ge 2 Sb 2 Te 5 -(N) films and the Johnson-Mehl-Avrami equation revealed that the crystallization process of amorphous Ge 2 Sb 2 Te 5 -(N) films changes depending on the nitrogen content. The crystallization behavior of Ge 2 Sb 2 Te 5 film revealed a two-step process that includes spherical-nucleation and disc-shaped grain growth. In contrast, nitrogen-doping into Ge 2 Sb 2 Te 5 thin films suppresses the second step and the crystallization of Ge 2 Sb 2 Te 5 -(N) becomes a onestep process that is the primary nucleation process. The number of nucleation sites during the crystallization of amorphous Ge 2 Sb 2 Te 5 -(N) films, increased markedly with the annealing temperature in the spherically shaped nuclei and eventually saturated. The effective crystallinity of Ge 2 Sb 2 Te 5 -(N) alloy films decreased with the increase in nitrogen content, mainly due to the grain-size refinement.