Photocatalytic Au-Bi2S3 heteronanostructures.

Au-Bi2S3 heteronanostructure photocatalysts were designed in which the coupling of a metal plasmon and a semiconductor exciton aids the absorption of solar light, enhances charge separation, and results in improved catalytic activity. Furthermore, these nanostructures show a unique pattern of structural combination, with Au nanoparticles positioned at the center of Bi2S3 nanorods. The chemistry of formation of these nanostructures, their epitaxy at the junction, and their photoconductance were studied, as well as their photoresponse properties.

Ag2S-AgInS2: p-n junction heteronanostructures with quasi type-II band alignment.

We report here the fabrication of a p-n junction diode in a single nanostructure by synthesizing a heterostructure involving n-type AgInS2 and p-type Ag2S. The quasi type-II band alignment between these ternary-binary semiconductors in the p-n junction heterostructures also slows down the carrier recombination rate and the heterostructures show rectification behavior. Hence, they can be used as an active material for fabrication of bulk heterojunction photovoltaic devices without any additional semiconductor material or dye required for charge separation or formation of a p-n junction.

Au-thiol interaction chemistry to influence the structural transformation of semiconductor nanocrystals and formation of giant nanostructures.

Giant nanostructures which are difficult to design by the classical growth process can be fabricated in a facilitated and well programmed surface ligand removal protocol employing the thiol-gold strong interaction chemistry. When thiol capped small ZnSe seed nanocrystals are treated with amine capped gold particles, gold snatches the thiol ligands from ZnSe and forces them to agglomerate leading to the giant crystalline ZnSe nanostructures.

Tuning the emission colors of semiconductor nanocrystals beyond their bandgap tunability: all in the dope.

Adopting the concept of one dopant for one color, all the prominent emitting colors in the visible windows are obtained by doping selective dopants (Ag, Cu, Ni, and Cu) in an appropriate host (alloy of Cdx Zn1-x S) with fixed size/composition and bandgap. Analyzing the origin of these emissions the relative position of respective dopant states are correlated.

Mn-Doped Multinary CIZS and AIZS Nanocrystals.

Multinary nanocrystals (CuInS2, CIS, and AgInS2, AIS) are widely known for their strong defect state emission. On alloying with Zn (CIZS and AIZS), stable and intense emission tunable in visible and NIR windows has already been achieved. In these nanocrystals, the photogenerated hole efficiently moves to the defect-induced state and recombines with the electron in the conduction band.