Metal-semiconductor core-shell nanostructures have been synthesized to explore the influence of metal nanostructures on the photoluminescence of semiconductors. Up to 40 times enhancement in the emission intensity was observed in the Au–CdS core-shell nanostructures. The mechanism where the excited electrons on Au surface by surface plasmon wave transfer to the conduction band of the CdS shell and recombine with holes in the valence band was proposed to interpret the enhancement. Our model can also be used to explain the quenched emission in FePt–CdS core-shell nanostructures and Au–CdSe nanodumbbells.

We have presented the voltage-controlled tuning of plasmonic response of absorption spectra of gold nanorods in liquid crystals. We observe that gold nanorods can be aligned along the rubbed polyimide substrate before applying external voltage. It is found that the transverse mode of gold nanorods shows a blueshift or a redshift when rotating the analyzer parallel or perpendicular to the rubbing direction, respectively, while all longitudinal modes display a redshift behavior. This work offers an easy way to tune the transverse and longitudinal modes of gold nanorods simultaneously, which makes it feasible to establish the color tunable devices.

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Optical photoluminescence studies are performed in self-ion (Ga + )-implanted nominally doped n-GaN nanowires. A 50-keV Ga + focused ion beam (FIB) in the fluence range of 1x10 14 -2x10 16 ions cm -2 is used for the irradiation process. A blueshift is observed for the yellow luminescence (YL) band with increasing fluence. Donor-acceptor pair (DAP) model with emission involving shallow donor introduced by point-defect clusters related to nitrogen vacancies and probable deep acceptor created by gallium interstitia l clusters is made responsible for the shift. High temperature annealing in nitrogen ambient restores the peak position of YL band by removing nitrogen vacancies.

Electrical bistable behaviour was demonstrated in memory devices based on n-type FeS2 nanocrystals (NCs) embedded in a p-type poly(3-hexylthiophene) (P3HT) matrix. An organic/inorganic hybrid non-volatile memory device with a type-II band alignment, fabricated by a spin-coating process, exhibited electrical bistable characteristics. The bistable behaviour of carrier transport can be well described through the space-charge-limited current model. The small amount of FeS2 NCs in this device serve as an excellent charge trapping medium arising from the type-II band alignment between FeS2 and P3HT. Our study suggests a new way to integrate non-volatile memory with other devices such as transistor or photovoltaic since the presented FeS2/P3HT offers a type-II band alignment.