Solar device fabrication limiting power conversion losses
Separation of individual strips from a solar cell workpiece, is accomplished by excluding a junction (e.g., a homojunction such as a p-n junction, or a heterojunction such as a p-i-n junction) from regions at which separation is expected to occur. According to some embodiments, the junction is excluded by physical removal of material from inter-strip regions of the workpiece. According to other embodiments, exclusion of the junction is achieved by changing an effective doping level (e.g., counter-doping, deactivation) at inter-strip regions. For still other embodiments, the junction is never formed at inter-strip regions in the first place (e.g., using masking during original dopant introduction). By imposing distance between the junction and defects arising from separation processes (e.g., backside crack propagation), losses attributable to electron-hole recombination at such defects are reduced, and collection efficiency of shingled modules is enhanced.
1. A method comprising:
forming a solar cell workpiece comprising a p-n junction;
excluding the p-n junction from an inter-strip region; and
separating a strip from the solar cell workpiece in the inter-strip region by application of stress along a scribing path to create a mechanical cleavage which propagates to a front side of the solar cell workpiece.
2. A method as in claim 1 wherein the strip comprises a Passivated Emitter Rear Contact (PERC) solar device.
3. A method as in claim 1 wherein the strip comprises a Tunnel Oxide Passivated Contact (TOPCon) solar device.
4. A method as in claim 1 wherein the strip is selected from the group comprising:
Poly-Silicon-On-Oxide (POLO) solar device;
Passivated Emitter Rear Totally-Diffused (PERT) solar device;
Passivated Emitter Rear Locally-Diffused (PERL) solar device.
5. A method as in claim 1 wherein excluding the p-n junction comprises removing material from the solar cell workpiece.
6. A method as in claim 5 wherein removing material from the solar cell workpiece comprises ablation.
7. A method of claim 6 wherein the ablation is caused by a laser.
8. A method of claim 5 further comprising forming a passivation layer where the material has been removed.
9. A method of claim 8 wherein the passivation layer comprises a functional layer.
10. A method as in claim 1 wherein excluding the p-n junction comprises changing a level of dopant.
11. A method as in claim 10 wherein changing the level of dopant comprises introducing a counter-dopant.
12. A method as in claim 11 wherein introducing the counter-dopant comprises diffusion.
13. A method as in claim 11 wherein introducing the counter-dopant comprises implantation.
14. A method as in claim 10 wherein changing the level of dopant comprises deactivation.
15. A method as in claim 1 wherein excluding the p-n junction comprises blocking dopant from entering the inter-strip region.
16. A method as in claim 15 wherein blocking the dopant comprises forming a mask over the inter-strip region.
17. A method as in claim 16 wherein the p-n junction is formed by implantation.
18. A method comprising:
forming a solar cell workpiece comprising a p-i-n junction;
excluding the p-i-n junction from an inter-strip region; and
separating a strip from the solar cell workpiece in the inter-strip region by application of stress along a scribing path to create a mechanical cleavage which propagates to a front side of the solar cell workpiece.
19. A method as in claim 18 wherein excluding the p-i-n junction comprises removing material from the solar cell workpiece.
20. A method as in claim 18 wherein excluding the p-i-n junction comprises blocking dopant from entering the inter-strip region.
21. A method as in claim 20 wherein blocking dopant comprises forming a mask over the inter-strip region.
22. A method as in claim 18 wherein the p-i-n junction is formed by vapor deposition.
23. A method as in claim 18 wherein the strip comprises a Heterojunction (HJT) solar device.
24. A method as in claim 23 wherein the HJT solar device comprises a Transparent Conductive Oxide (TCO) layer.
25. A method as in claim 24 further comprising removing the TCO layer at the inter-strip region by wet etching.
26. A method as in claim 24 further comprising blocking the TCO layer from being formed in the inter-strip region using a mask.
27. A method comprising:
forming a solar cell workpiece comprising a Transparent Conducting Oxide (TCO) layer;
excluding the TCO layer from an inter-strip region; and
separating a strip from the solar cell workpiece in the inter-strip region to form a Heterojunction (HJT) solar device by application of stress along a scribing path to create a mechanical cleavage which propagates to a front side of the solar cell workpiece.
28. A method as in claim 27 wherein excluding the TCO layer comprises blocking the TCO layer from being formed in the inter-strip region using a mask.
29. A method as in claim 27 wherein excluding the TCO layer comprises removing the TCO layer at the inter-strip region.