Photovoltaic device using single wall carbon nanotubes and method of fabricating the same
View Patent ↗A photovoltaic device and methods for forming the same. In one embodiment, the photovoltaic device has a silicon substrate, and a film comprising a plurality of single wall carbon nanotubes disposed on the silicon substrate, wherein the plurality of single wall carbon nanotubes forms a plurality of heterojunctions with the silicon in the substrate.
1. A method of forming a heterojunction structure, comprising the steps of:
(a) preparing a silicon substrate; and
(b) depositing a film on the silicon substrate, the film comprising a plurality of single wall carbon nanotubes, whereby forming a plurality of heterojunctions between the single wall carbon nanotubes and silicon by elevating temperature to about 150° C., such that no reaction occurs at each heterojunction to form SiC.
2. The method of claim 1 , wherein the step of depositing comprises the steps of:
(b1) preparing a solution of single wall carbon nanotubes dissolved in a solvent; and
(b2) spraying the solution of single wall carbon nanotubes on the silicon substrate using a carrier gas.
3. The method of claim 2 , wherein the carrier gas is dry air.
4. The method of claim 2 , wherein the solvent is dimethylformamide (DMF).
5. The method of claim 2 , further comprising the step of heating the silicon substrate and the film to an elevated temperature following the step of spraying to evaporate the solvent.
6. The method of claim 5 , wherein the heating temperature is about 150° C.
7. The method of claim 2 , further comprising the step of spraying the solution of single wall carbon nanotubes on the silicon substrate using a carrier gas at least one more time following the step of spraying to change the thickness of the film.
8. The method of claim 1 , further comprising the step of treating the film of single wall carbon nanotubes with thionyl chloride (SOCl 2 ).
9. The method of claim 8 , wherein the step of treating comprises the step of applying droplets of SOCl 2 onto the film of single wall carbon nanotubes.
10. The method of claim 1 , wherein the plurality of single wall carbon nanotubes forms a randomly distributed porous network.
11. The method of claim 10 , wherein the film of single wall carbon nanotubes has a thickness in the range between about 20 nm and 300 nm.
12. The method of claim 11 , wherein the film of single wall carbon nanotubes has an optical transmittance in the range between about 45% and 90% for 550 nm wavelength light.
13. The method of claim 12 , wherein the film of single wall carbon nanotubes has an optical transmittance of about 60% for 550 nm wavelength light.
14. The method of claim 1 , wherein the substrate comprises n-type silicon.
15. The method of claim 1 , wherein the substrate comprises p-type silicon.
16. The method of claim 1 , wherein the substrate comprises crystalline silicon.
17. The method of claim 1 , wherein the substrate comprises polycrystalline silicon in thin-film form.
18. An article of manufacture made by the method of claim 1 .
19. A method of forming a heterojunction structure, comprising the steps of:
(a) preparing a silicon substrate;
(b) preparing a solution of single wall carbon nanotubes dissolved in a solvent;
(c) spraying the solution of single wall carbon nanotubes on the silicon substrate to form a film of single wall carbon nanotubes; and
(d) heating the silicon substrate and the film to an elevated temperature about 150° C. to evaporate the solvent such that a film is deposited on the silicon substrate, the film comprising a plurality of single wall carbon nanotubes, wherein a plurality of heterojunctions between the single wall carbon nanotubes and silicon is formed.
20. The method of forming a heterojunction structure, wherein the plurality of heterojunctions between the single wall carbon nanotubes and silicon is formed without reaction occuring at each heterojunction to form SiC.