High-efficiency solar cell structures and methods of manufacture
View Patent ↗Solar cells of varying composition are disclosed, generally including a central substrate, conductive layer(s), antireflection layers(s), passivation layer(s) and/or electrode(s). Multifunctional layers provide combined functions of passivation, transparency, sufficient conductivity for vertical carrier flow, the junction, and/or varying degrees of anti-reflectivity. Improved manufacturing methods including single-side CVD deposition processes and thermal treatment for layer formation and/or conversion are also disclosed.
1. A method of fabricating a solar cell, comprising:
providing a substrate;
providing an interface passivation layer over the substrate;
providing a passivating film over the interface passivation layer, the passivating film comprising a passivating material and a conductive dopant;
wherein providing the interface passivation layer and providing the passivating film comprise:
providing an amorphous silicon-containing compound over an upper surface of the substrate, the compound comprising oxygen dopant and the conductive dopant;
thermally treating the amorphous silicon-containing compound to diffuse the oxygen dopant, at least in part, into the upper surface of the substrate to form an oxide layer over the substrate, the oxide layer defining the interface passivation layer; and
wherein remaining amorphous silicon-containing compound above the oxide layer defines the passivating film; and
wherein the thermally treating also diffuses at least a portion of the conductive dopant throughout the interface passivation layer to facilitate electrical connection to the substrate; and
providing at least one electrode over the passivating film, wherein the conductive dopant within the passivating film and throughout the interface passivation layer provides direct electrical connection between the at least one electrode and the substrate.
2. The method of claim 1 , wherein the thermally treating crystallizes, at least in part, the passivating film to establish a crystallized passivating film.
3. The method of claim 2 , wherein the crystallized passivating film is a transparent film.
4. The method of claim 2 , wherein the crystallization of the passivating film improves a passivation of the passivating film.
5. The method of claim 2 , wherein the interface passivation layer protects the substrate from crystallization or re-crystallization during the thermally treating and crystallization of the passivating film.
6. The method of claim 1 , wherein the interface passivation layer has a thickness selected to permit tunneling of electrical carriers through the interface passivation layer into the substrate.
7. The method of claim 1 , wherein the thermally treating diffuses a portion of the conductive dopant through the interface passivation layer into the substrate.
8. The method of claim 1 , further comprising providing an anti-reflective film over the conductive upper surface of the passivating film.
9. The method of claim 1 , wherein the at least one electrode only electrically connects to the substrate through the passivating film via the conductive dopant.