Nanostructured thin film inorganic solar cells
Inorganic solar cells having a nano-patterned p-n or p-i-n junction to reduce electron and hole travel distance to the separation interface to be less than the magnitude of the drift length or diffusion length, and meanwhile to maintain adequate active material to absorb photons. Formation of the inorganic solar cells may include one or more nano-lithography steps.
1 . An inorganic solar cell, comprising:
a patterned p-type material layer formed of inorganic semi-conducting material, the p-type material layer having a first set of protrusions and a first set of recessions;
an intrinsic layer positioned on the patterned p-type material layer, thickness of the intrinsic layer configured to be less than magnitude of diffusion length for the inorganic semi-conducting material; and,
an n-type material layer positioned on the intrinsic layer.
2 . The inorganic solar cell of claim 1 , wherein at least one protrusion includes a variable width providing a non-vertical wall angle.
3 . The inorganic solar cell of claim 1 , wherein shape of at least one protrusion is selected from a group consisting of circle, square, rectangle, triangle, and polygon.
4 . The inorganic solar cell of claim 1 , wherein thickness of the intrinsic layer is less than a magnitude of drift length for the solar cell.
5 . The inorganic solar cell of claim 1 , wherein the plurality of protrusions and the plurality of recessions of the p-type material layer are formed using an imprint lithography template.
6 . The inorganic solar cell of claim 1 , further comprising:
an electrode layer positioned adjacent to the p-type layer, the electrode layer having a second set of protrusions and a second set of recessions, wherein the p-type material layer forms a conformal layer on the electrode layer such that the first set of protrusions and the first set of recessions are formed.
7 . The inorganic solar cell of claim 6 , wherein at least one protrusion of the second set of protrusions is formed having a variable width providing a non-vertical wall angle.
8 . The inorganic solar cell of claim 6 , wherein shape of at least one protrusion of the second set of protrusions is selected from a group consisting of circle, square, rectangle, triangle, and polygon
9 . The inorganic solar cell of claim 6 , wherein the plurality of protrusions and the plurality of recessions are formed by a metal etchant using an imprinting resist as a mask.
10 . The inorganic solar cell of claim 1 , wherein the inorganic semi-conducting material is selected from a group consisting of amorphous silicon, copper indium gallium selenide, microcrystalline silicone, and nanocrystalline silicon.
11 . A method of forming an inorganic solar cell, comprising:
depositing an intrinsic layer on a patterned p-type material layer formed of inorganic semi-conducting material, the patterned p-type material layer having a first set of protrusions and a first set of recessions; and,
depositing an n-type material layer on the intrinsic layer,
wherein thickness of the intrinsic layer is configured to be less than magnitude of diffusion length for the inorganic semi-conducting material.
12 . The method of claim 11 , further comprising:
depositing p-type material on an electrode layer;
positioning an imprint lithography template in superimposition with the p-type material and reducing a distance between the template and the electrode layer such that p-type material fills a volume between the template and the electrode layer; and,
solidifying the p-type material forming the patterned p-type material layer having the first set of protrusions and the first set of recessions.
13 . The method of claim 11 , further comprising:
depositing p-type material on a patterned electrode layer by conformal deposition forming the patterned p-type material layer, the patterned electrode layer having a second set of protrusions and a second set of recessions.
14 . The method of claim 13 , further comprising:
depositing an organic monomer material layer on an electrode layer, the organic monomer material layer having a series of gaps sized and configured to provide exposed portions of the electrode layer;
exposing the organic monomer material layer and the exposed portions of the electrode layer to an etchant forming the second set of protrusions and the second set of recessions.
15 . The method of claim 14 , wherein the gaps are formed using an imprint lithography process.
16 . The method of claim 14 , wherein the gaps are formed by a break through etch process.
17 . The method of claim 14 , wherein the etchant is a weak acid.
18 . The method of claim 14 , wherein the second set of protrusions and the second set of recessions form concave arc-like structures in the electrode layer.
19 . The method of claim 11 , wherein at least one protrusion has a variable width providing a non-vertical wall angle.
20 . A method of forming an inorganic solar cell, comprising:
depositing electrode material on a substrate;
etching the electrode material forming a patterned electrode layer having a plurality of protrusions and a plurality of recessions;
depositing a conformal layer of inorganic semi-conducting material on the electrode patterned electrode layer forming a patterned p-type material layer;
depositing an intrinsic layer on the patterned p-type material layer; and,
depositing an n-type material layer on the intrinsic layer.
21 . The method of claim 20 , wherein thickness of the intrinsic layer is less than diffusion length for the inorganic semi-conducting material.
22 . An inorganic solar cell, comprising:
a patterned n-type material layer having a first set of protrusions and a first set of recessions;
an intrinsic layer positioned on the patterned n-type material layer; and,
a p-type material layer formed of inorganic semi-conducting material positioned on the intrinsic layer;
wherein thickness of the intrinsic layer is configured to be less than magnitude of diffusion length for the inorganic semi-conducting material.