1/We claim:
1. A semi conductor nanocry stal (100) compri sing:
a core (102) fabricated from a first semiconductor; and a shell (104) enclosing the core (102) non-uniformly, wherein the shell (104) is fabricated from a second semiconductor, wherein the optical cross section of the semiconductor nanocrystal (100) is in a range of 10"17 cm2 - 10"12 cm2 in a 2 - 3 eV region, wherein the core (102) is less than 2 nanometers from an outer surface of the shell (104) in at least one region of the semiconductor nanocrystal (100), and wherein a shape of the semiconductor nanocrystal (100) is elongated.
2. The semiconductor nanocrystal (100) as claimed in claim 1, wherein a core band offset is staggered compared to a shell band offset.
3. The semiconductor nanocrystal (100) as claimed in claim 1, wherein a longest dimension of the semiconductor nanocrystal (100) is in a range of 3 nanometers to 25 nanometers.
4. The semiconductor nanocrystal (100) as claimed in claim 1, wherein a mean aspect ratio of the semiconductor nanocrystal (100) is in a range of 1:1-1:10.
5. The semiconductor nanocrystal (100) as claimed in claim 2, wherein the first semiconductor is selected from the group consisting of CuAlS2, CdSe, CuGaS2, CuInS2, ZnTe, ZnSe, GaN, A1N, GaP, InP, InN, A1P, AlAs, Copper doped ZnS, Copper doped ZnSe, AgAlS, CuAlSe2, CuAlTe2, CuGaSe2, CuGaTe2, AgGaS2. ZnS, SiC, CuFeS2, CdS, CdTe, Ti02, ZnO, AgFeS2, AuFeS2, CuFeSe2, CuFeTe2, CuCoS2, CuCoSe2, CuCoTe2, AgCoS2, AgCoSe2, AgCoTe2, CuCrS2, CuCrSe2, CuCrTe2, aluminium gallium and indium ternary compounds, and the like and alloys, thereof and the second semiconductor is selected from the group consisting of ZnS, CuAlS2, CuGaS2, CuInS2, ZnTe, ZnSe, GaN, A1N, GaP, InP,

InN, A1P, AlAs, Copper doped ZnS, Copper doped ZnSe, AgAlS, CuAlSe2, CuAlTe2, CuGaSe2, CuGaTe2, AgGaS2, SiC, CuFeS2, CdSe, CdS, CdTe, Ti02, ZnO, AgFeS2, AuFeS2, CuFeSe2, CuFeTe2, CuCoS2, CuCoSe2, CuCoTe2, AgCoS2, AgCoSe2, AgCoTe2, CuCrS2, CuCrSe2, CuCrTe2, aluminium gallium and indium based ternary compounds and the like and alloys, thereof.
6. The semiconductor nanocrystal (100) of claim 1, where the core (102) is composed of CuAlS2 or alloys thereof and the shell (104) is composed of ZnS or alloys thereof.
7. A method for preparing a semiconductor nanocrystal (100) comprising:
preparing a core (102), wherein the core (102) is a copper aluminium sulfide core, wherein preparing the core (102) comprises: preparing a core anion precursor; preparing a core cation precursor; and contacting the core anion precursor with the core cation precursor to obtain the core (102); and
preparing a shell (104) enclosing the core (102) non-uniformly, wherein the shell (104) is a zinc sulfide shell, wherein preparing the shell (104) comprises:
heating the core (102) to a temperature in a range of 150-280 0 C; and
contacting the core (102) with shell precursors to obtain the semiconductor nanocrystal (100), wherein the optical cross section of the semiconductor nanocrystal (100) is in a range of 10"17 cm2 - 10"12 cm2 in a 2 - 3 eV region, wherein the core (102) is less than 2 nanometers from an outer surface of the shell (104) in at least one region of the semiconductor nanocrystal (100), and wherein a shape of the semiconductor nanocrystal (100) is elongated.

8. The method as claimed in claim 7, wherein:
preparing the core anion precursor comprises contacting sulfur with a mixture of oleylamine and octadecene in an inert atmosphere at a temperature range of 25°C - 300°C to obtain the core anion precursor;
preparing the core cation precursor comprises contacting a copper salt and aluminium salt with a liquid medium comprising an organic acid in an inert atmosphere at 85-285 °C for a time period of 10-20 minutes to obtain the core cation precursor; and
contacting the core anion precursor with the core cation precursor to obtain the core comprises:
contacting the core cation precursor with an organic thiol to
obtain a first mixture; and
contacting the core anion precursor with the first mixture at a
temperature range of 160-285 °C to obtain the copper aluminium
sulfide core.
9. A method for photosynthesis of organic compounds, the method comprising:
contacting a plurality of semiconductor nanocrystals (100) with a dispersion of salts selected from the group consisting of carbonates, bicarbonates, and carboxylates in water to obtain a first composition, wherein each of the plurality of semiconductor nanocrystals (100) comprises:
a core (102) fabricated from a first semiconductor; and a shell (104) fabricated from a second semiconductor, wherein the optical cross section of the semiconductor nanocrystal (100) is in a range of 10"17 cm2 - 10"12 cm2 in a 2 - 3 eV region, and wherein the core (102) is less than 2 nanometers from an outer surface of the shell (104) in at least one region of the semiconductor nanocrystal (100); and
irradiating the first composition with light to obtain the organic compounds.

10. The method as claimed in claim 9, wherein products of irradiating the first
composition are organic compounds selected from the group comprising
formate, acetate, methanol and butanol.
11. The method as claimed in claim 9, wherein the contacting comprises:
contacting salts with water to obtain the dispersion; and adding the plurality of semiconductor nanocrystals (100) to the dispersion.
12. The method as claimed in claim 9, wherein the contacting comprises:
depositing the plurality of semiconductor nanocrystals (100) on an inner surface of a vessel to obtain a coated vessel;
contacting the salts with water to obtain the dispersion; and adding the dispersion to the coated vessel.
13. The method as claimed in claim 9, wherein concentration of salts in the dispersion is in a range of 1 micromolar to 10 molars.
14. The method as claimed in claim 9, wherein the dispersion comprises a first fraction of salts soluble in water and a second fraction of salts insoluble in water.
15. The method as claimed in claim 9, wherein the method comprises providing the plurality of semiconductor nanocrystals as a plurality of layers on an inert substrate.
16. The method as claimed in claim 15, wherein the inert substrate comprises a granular material with grain size in a range of 50 nm to 1 cm, wherein the inert substrate is selected from the group consisting glass, silicate glass, non-silicate glass, silica, activated silica, zeolite, sapphire, alumina, calcite, calcium fluoride, magnesium fluoride, barium fluoride, mica, teflon, anodized aluminum, ZnO, Ti02, and combinations, thereof.