Efficient Black Silicon Photovoltaic Devices With Enhanced Blue Response
First Claim
1. A photovoltaic device with enhanced blue response, comprising:
- a silicon substrate;
an emitter layer on a side of the silicon substrate, the emitter layer having a dopant level providing a sheet resistance of at least 90 ohms/sq; and
an antireflective surface on the emitter layer comprising black silicon.
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Accused Products
Abstract
A photovoltaic (PV) device with improved blue response. The PV device includes a silicon substrate with an emitter layer on a light receiving side. The emitter layer has a low opant level such that it has sheet resistance of 90 to 170 ohm/sq. Anti-reflection in the PV device is provided solely by a nano-structured or black silicon surface on the light-receiving surface, through which the emitter is formed by diffusion. The nano structures of the black silicon are formed in a manner that does not result in gold or another high-recombination metal being left in the black silicon such as with metal-assisted etching using silver. The black silicon is further processed to widen these pores so as to provide larger nanostructures with lateral dimensions in the range of 65 to 150 nanometers so as to reduce surface area and also to etch away a highly doped portion of the emitter.
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Citations
28 Claims
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1. A photovoltaic device with enhanced blue response, comprising:
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a silicon substrate; an emitter layer on a side of the silicon substrate, the emitter layer having a dopant level providing a sheet resistance of at least 90 ohms/sq; and an antireflective surface on the emitter layer comprising black silicon. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 14)
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9. A photovoltaic device, comprising:
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a silicon wafer with a back surface and a front, light-receiving surface; a layer of black silicon, on the front, light-receiving surface, comprising a plurality of nanostructures with lateral structure dimensions greater than 65 nanometers; and an emitter comprising dopant diffused a depth into the front, light-receiving surface through and beyond the layer of the black silicon, wherein a maximum level of the dopant is less than about 3×
1021 cm−
3. - View Dependent Claims (10, 11, 12, 13)
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15. A method of fabricating photovoltaic devices, comprising:
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forming black silicon on a surface of a silicon substrate; forming an emitter in the silicon substrate by diffusing a dopant into the black silicon surface; processing the silicon substrate to remove an outer layer of the black silicon surface to remove a volume of highly doped silicon; forming a surface passivation coating on the black silicon surface; and attaching front and back electrical contacts to the silicon substrate. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22)
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23. A method of making a photovoltaic device, comprising:
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forming a black silicon layer comprising nanostructures on a surface of a silicon substrate; processing the surface of the silicon substrate to remove an outer portion of the black silicon layer to increase the lateral structure dimensions of the nanostructures; forming an emitter in the silicon substrate by diffusing a dopant into the black silicon layer; and forming a surface passivation coating on the black silicon layer. - View Dependent Claims (24, 25, 26, 27)
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28. A method of fabricating a photovoltaic device, comprising:
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forming black silicon on a surface of a silicon wafer; and forming an emitter in the surface of the silicon wafer including diffusing a dopant into the black silicon, wherein the forming of the black silicon includes increasing average lateral structure dimensions of nanostructures in the black silicon to a range of 65 to 200 nanometers, and wherein the emitter has a dopant level providing a sheet resistance of at least about 90 ohm/sq.
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Specification