Hsuan-Ching Lin

We present the control of couplings between quantum dots and cavity modes in microdisk microcavities by a stress tuning scheme. The excitonic transitions and cavity modes can be brought into resonance due to their different energy shift rates with the applied strain. Spectral signatures of both strong and weak couplings are clearly observed. The strain tunable device can be used to tune the exciton wavelength bidirectionally at constant temperatures without significantly affecting the emission rate and linewidth of excitons. DOI: http://dx.doi.org/10.1103/PhysRevB.84.201301 ©2011 American Physical Society

In the present study, tungsten oxide nanomaterials were synthesized by a modified plasma arc gas condensation technique. The effects of processing parameters (plasma current ranged from 70∼90 A and chamber pressure ranged from 200∼600 torr) on the preparation of tungsten oxide nanomaterials were investigated. X-ray diffraction results showed that all of the nanomaterials synthesized in the present study exhibited W₅O₁₄ phase. Field emission scanning electron microscopy and transmission electron microscopy examinations revealed that the tungsten oxide nanomaterials were equiaxed when prepared at a relatively low plasma current of 70 A, and turned into rod-like nanoparticles with increasing plasma current (80 or 90 A). Generally, the relative amount, diameter, and length of tungsten oxide nanorods increased with increasing plasma currents or chamber pressures. The aspect ratio of the as-prepared tungsten oxide nanorods reached a maximum of 12.7 when a plasma current of 90 A and a chamber pressure of 400 torr were used. A growth mechanism for tungsten oxide nanorods was proposed.

In this study, Ti-doped W18O49 nanorods were prepared without any templates or catalysts using a modified plasma-arc gas-condensation technique. Structure investigations were conducted and the optical properties of the as-prepared nanorods were characterized by field emission gun scanning electron microscope, high-resolution transmission electron microscope, x-ray diffractometer, x-ray photoelectron spectroscope, micro-Raman, and ultraviolet (UV)-visible spectrometers. The experimental results showed that the diameter and the length of the as-prepared nanorods were approximately 20nm and 3μm, respectively. The as-prepared nanorods exhibited W18O49 structures and characteristic Raman peaks could be observed. UV-visible absorption investigations revealed that Ti-doped W18O49 nanorods exhibited a redshift phenomenon when compared with the pure TiO2 and WO3.

In the present study, non-stoichiometric tungsten oxide (WO _3-x ) nanomaterials synthesized by a modified plasma arc gas condensation technique were added into anatase titanium oxide (a-TiO ₂ ) which was used as photoanode materials in dye-sensitized solar cells (DSSC). The WO _3-x /a-TiO ₂ sample was characterized by FESEM, XRD, HRTEM, XPS and UV-visible spectra techniques. The photovoltaic efficiency of the DSSC fabricated by WO _3-x /a-TiO ₂ was measured under the simulated solar light system with AM1.5 filter. The results showed the enhanced cell performance by incorporation of WO _3-x and the highest efficiency acquired is 6.16 % for DSSC fabricated by 10wt% WO _3-x /TiO ₂ sample. The possible explanation for the efficiency enhancement can be attributed to the additive of WO _3-x nanomaterials to form the defects in the WO _3-x /TiO ₂ lattices and the imperfect structures of WO ₃ , accelerating the electron transport rate.