Metal chalcogenide composite nano-particles and layers therewith

1. 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.

2. 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, and wherein a stoichiometric deficit of the chalcogenide in said metal chalcogenide composite nano-particle is present.

3. The metal chalcogenide composite nano-particle according to claim 2 , wherein said metal chalcogenide composite nano-particle comprises a p-type semiconducting metal chalcogenide phase and a n-type semiconducting chalcogenide phase, and wherein the concentration of said p-type semiconducting metal chalcogenide in said metal chalcogenide composite nano-particle is at least 5 mole percent and is less than 50 mole percent.

4. The metal chalcogenide composite nano-particle according to claim 2 , wherein said metal chalcogenide composite particle is a coprecipitated particle.

5. The metal chalcogenide composite nano-particle according to claim 2 , wherein said metal chalcogenide composite particle is a metal sulphide composite particle.

6. The metal chalcogenide composite nano-particle according to claim 2 , wherein said metal capable of forming n-type semiconducting chalcogenide nano-particles is selected from the group consisting of zinc, bismuth, cadmium, mercury, indium, tin, tantalum and titanium.

7. The metal chalcogenide composite nano-particle according to claim 6 , wherein said metal capable of forming p-type semiconducting chalcogenide nano-particles is selected from the group consisting of copper, chromium, iron, lead and nickel.

8. The metal chalcogenide composite nano-particle according to claim 7 , 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, and wherein said metal capable of forming spectrally sensitizing chalcogenide nano-particles is selected from the group consisting of silver, lead, copper, bismuth, vanadium and cadmium.

9. The metal chalcogenide composite nano-particle according to claim 2 , wherein said metal capable of forming p-type semiconducting chalcogenide nano-particles is selected from the group consisting of copper, chromium, iron, lead and nickel.

10. The metal chalcogenide composite nano-particle according to claim 2 , 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.

11. The metal chalcogenide composite nano-particle according to claim 10 , wherein said metal capable of forming spectrally sensitizing chalcogenide nano-particles is selected from the group consisting of silver, lead, copper, bismuth, vanadium and cadmium.

12. 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, and wherein said metal capable of forming p-type semiconducting chalcogenide nano-particles is selected from the group consisting of copper, chromium, iron and nickel.

13. The metal chalcogenide composite nano-particle according to claim 12 , wherein said metal chalcogenide composite nano-particle comprises a p-type semiconducting metal chalcogenide phase and a n-type semiconducting chalcogenide phase, and wherein the concentration of said p-type semiconducting metal chalcogenide in said metal chalcogenide composite nano-particle is at least 5 mole percent and is less than 50 mole percent.

14. The metal chalcogenide composite nano-particle according to claim 12 , wherein said metal chalcogenide composite particle is a coprecipitated particle.

15. The metal chalcogenide composite nano-particle according to claim 12 , wherein said metal chalcogenide composite particle is a metal sulphide composite particle.

16. The metal chalcogenide composite nano-particle according to claim 12 , wherein said metal capable of forming n-type semiconducting chalcogenide nano-particles is selected from the group consisting of zinc, bismuth, cadmium, mercury, indium, tin, tantalum and titanium.

17. The metal chalcogenide composite nano-particle according to claim 16 , 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, and wherein said metal capable of forming spectrally sensitizing chalcogenide nano-particles is selected from the group consisting of silver, lead, copper, bismuth, vanadium and cadmium.

18. The metal chalcogenide composite nano-particle according to claim 12 , 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.

19. The metal chalcogenide composite nano-particle according to claim 18 , wherein said metal capable of forming spectrally sensitizing chalcogenide nano-particles is selected from the group consisting of silver, lead, copper, bismuth, vanadium and cadmium.

20. 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, wherein said metal capable of forming p-type semiconducting chalcogenide nano-particles is selected from the group consisting of copper, chromium, iron, lead and nickel, 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, and wherein said metal capable of forming spectrally sensitizing chalcogenide nano-particles is selected from the group consisting of silver, lead, copper, bismuth, vanadium and cadmium.

21. A dispersion comprising 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.

22. A layer comprising metal chalcogenide composite nano-particles 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.

23. The layer according to claim 22 , wherein said layer further contains at least one spectral sensitizer for said metal chalcogenide composite nano-particles.

24. The layer according to claim 23 , wherein said at least one spectral sensitizer is selected from the group consisting of metal chalcogenide nano-particles with a band-gap between 1.0 and 2.9 eV, organic dyes, and metallo-organic dyes.

25. The layer according to claim 22 , wherein said layer further comprises a binder.

26. The layer according to claim 25 , wherein said binder is poly(vinyl pyrrolidone).

27. A photovoltaic device comprising a layer comprising metal chalcogenide composite nano-particles 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.