CdSeTe photovoltaic devices with interdigitated back contact architecture
Disclosed herein are CdSeTe photovoltaic devices having interdigitated back contact architecture for use in polycrystalline thin films in photovoltaic devices.
1. A method for making a polycrystalline CdSeTe device comprising an interdigitated back contact architecture wherein the CdSeTe device comprises a CdSeTe film and wherein the CdSeTe device exhibits a minority carrier lifetime of at least 100 ns.
2. The method of claim 1 wherein the CdSeTe device exhibits a lateral diffusion length of at least 5 μm.
3. The method of claim 1 wherein the CdSeTe device exhibits a minority carrier lifetime of at least 100 ns and a lateral diffusion length of at least 5 μm.
4. A method for making a polycrystalline CdSeTe device comprising an interdigitated back contact architecture wherein the method comprises a first step of a deposition of a first metal layer to a thickness of from about 100 to about 500 nm onto a substrate; and a second step of a deposition of an electrically insulating layer onto a metal/metal oxide layer; and a third step of a deposition of a 100 nm to 500 nm metal contact layer; and a fourth step of cutting through a top metal/metal oxide and insulating layers to expose a bottom metal/metal oxide layer.
5. The method of claim 4 wherein the CdSeTe device comprises a CdSeTe film.
6. The method of claim 5 wherein the CdSeTe device exhibits a minority carrier lifetime of at least 100 ns.
7. The method of claim 5 wherein the CdSeTe device exhibits a lateral diffusion length of at least 5 μm.
8. The method of claim 5 wherein the CdSeTe device exhibits a minority carrier lifetime of at least 100 ns and a lateral diffusion length of at least 5 μm.
9. A method for making a polycrystalline CdSeTe device comprising an interdigitated back contact architecture wherein the method comprises, a first step of a vacuum deposition of Cd(Se x Te 1-x ) onto an interdigitated back contact structure heated to about 450° C.; and a second step of annealing the interdigitated back contact and Cd(Se x Te 1-x ) structure at 500-600° ° C. while suspended over a powder comprising Cd(Se x Te 1-x ) wherein x is from zero to 0.4; and a third step of annealing the interdigitated back contact and Cd(Se x Te 1-x ) structure at from about 450 to about 525° C. while suspended over a CdCl 2 containing powder in an inert gas atmosphere for about 10 to 20 minutes; and a fourth step of coating the interdigitated back contact and Cd(Se x Te 1-x ) structure with a transparent passivation Al 2 O 3 layer of from about 20 nm to about 100 nm thickness; and a fifth step of treating the resulting device structure to a CdCl 2 anneal at a temperature of between about 400 and about 450° C.
10. The method of claim 9 wherein the fifth step of treating the resulting device structure to a CdCl 2 anneal at a temperature of between about 400 and about 450° C. occurs in an atmosphere containing oxygen.
11. The method of claim 9 wherein the fifth step of treating the resulting device structure to a CdCl 2 anneal at a temperature of between about 400 and about 450° C. occurs in an atmosphere lacking oxygen.
12. The method of claim 9 wherein the second step of annealing the interdigitated back contact and Cd(Se x Te 1-x ) structure at 500-600° C. while suspended over a powder comprising Cd(Se x Te 1-x ) wherein x is from zero to 0.4 results in an increase in the density of the Cd(Se x Te 1-x ).
13. The method of claim 9 wherein the CdSeTe device further comprises a CdSeTe film.
14. The method of claim 13 wherein the CdSeTe device exhibits a minority carrier lifetime of at least 100 ns and a lateral diffusion length of at least 5 μm.
15. A method for making a polycrystalline CdSeTe device comprising an interdigitated back contact architecture wherein the method comprises a first step of a non-vacuum deposition of colloidal nanocrystalline Cd(Se x Te 1-x ) onto an interdigitated back contact structure.
16. The method of claim 15 wherein the interdigitated back contact structure is made by a method comprising a first step of depositing colloidal Cd(Se x Te 1-x ) nanocrystals through layer-by-layer spincoating on interdigitated back contact substrates; and a second step of drying Cd(Se x Te 1-x ) films at about 150° C.; and a third step of dipping the interdigitated back contact and Cd(Se x Te 1-x ) structure in a saturated solution of CdCl 2 in methanol and rinsing with isopropanol; and a fourth step of sintering nanocrystalline films through thermal annealing at about 350° C. for about 20 to about 30 seconds; and repeating the first step, the second step, the third step and the fourth step until the deposited layer is from about 1 μm to about 2 μm; and a final step of coating the interdigitated back contact and Cd(Se x Te 1-x ) structure with a transparent passivation Al 2 O 3 layer of from about 20 nm to about 100 nm thickness.
17. The method of claim 16 wherein the first step of depositing colloidal Cd(Se x Te 1-x ) nanocrystals is through layer-by-layer bladecoating on interdigitated back contact substrates.
18. The method of claim 16 wherein the CdSeTe device further comprises a CdSeTe film and wherein the CdSeTe device exhibits a minority carrier lifetime of at least 100 ns and a lateral diffusion length of at least 5 μm.