Patent ID: 7468146

Claim:
A metal chalcogenide composite nano-particle comprising a metal capable of forming p-type semiconducting chalcogenide nano-particles and a metal capable of forming n-type semiconducting chalcogenide nano-particles, wherein at least one of said metal chalcogenides has a band-gap between 1.0 and 2.9 eV and the concentration of said metal capable of forming p-type semiconducting chalcogenide nano-particles is at least 5 atomic percent of said metal and is less than 50 atomic percent of said metal, wherein said metal capable of forming n-type semiconducting chalcogenide nano-particles is selected from the group consisting of zinc, bismuth, indium, tin, tantalum and titanium, and wherein said metal chalcogenide composite particle further comprises a metal capable of forming spectrally sensitizing chalcogenide nano-particles with a band-gap between 1.0 and 2.9 eV is selected from the group consisting of silver, lead, copper, bismuth, vanadium and cadmium.