Phase transition properties of the copolymer films of polyvinylidene fluoride (PVDF) and trifluoroethylene(TrFE), P(VDF-TrFE), were studied with X-ray diffraction (XRD) and polarization modulated ellipsometry (PME). XRD studies on both Langmuir-Blodgett (LB) films and spin coated films exhibit conversions from ferroelectric phase to paraelectric phase at 108±2℃ on heating and paraelectric phase to ferroelectric phase at 78±2℃ on cooling. The presence of the ferroelectric-paraelectric phase transition is also confirmed by the PME technique for the first time in this study. PME was proved to be a very sensitive tool in the measurement of the structural changes at the nano-thickness films.

In this paper, we analyzed the effects of the number of TIPS-pentacene droplets and also the substrate temperature on the performance of OTFTs As the number of the droplets increased, the mobility increased and reached the perk value and then reduced at all temperatures. The peak mobility was 0.14 ± 0.03 cm²/V sec at 3 droplets and 41℃, 0.19 ± 0.02 cm²/V.sec at 4 droplets and 46℃,and 0.35 ± 0.10 cm²/V sec at 7 droplets and 51℃. The reason of existence of peak mobility can be found in matching the evaporation of solvent with the velocity of crystal formation. When two parameters were properly matched, the mobility produced the highest.

Hydrogenated amorphous silicon (а-Si:H) layers deposited by plasma enhanced chemical vapor deposition (PECVD) are investigated for use in silicon hetero-junction solar cells employing n-type crystalline silicon (c-Si) substrates. The optical and structural properties of silicon hetero-junction devices have been characterized using spectroscopy ellipsometry and high resolution cross-sectional transmission electron micrograph (HRTEM). In addition, the effective carrier lifetime is measured by the quasi-steady-state photocoductance (QSSPC) method. We have studied on the correlation between the order of а-Si:H and the passivation quality at the interface of а-Si:H/c-Si. Base on the result, we have fabricated a silicon hetero-junction solar cell incorporating the а-Si:H passivation layer with on open circuit voltage (Voc) of 637 mV.