Passivated nanoparticles

A method for fabricating a passivated semiconductor nanocrystal, said method comprising the steps of:

• synthesizing an alloy-gradient nanoparticle, said nanoparticle comprising Cd, S and Se;
• applying a semiconductor coating comprising Zn and S over said alloy-gradient nanoparticle, said coating having a wider band gap than the alloy-gradient nanoparticle to provide a semiconductor coated alloy-gradient nanoparticle;
• coating the surface of the semiconductor coated alloy-gradient nanoparticle by growing monolayers of aluminum on the surface of the semiconductor coated alloy-gradient nanoparticle;
• and
• oxidizing the surface of said aluminum layer by exposure to an ambient environment to form an aluminum oxide layer thereon to provide a passivated semiconductor nanocrystal;
• wherein the semiconductor coated alloy-gradient nanoparticle with the aluminum oxide layer has less of a reduction in fluorescence than a semiconductor coated alloy-gradient nanoparticle not having an aluminum oxide layer.