VERTICAL PILLAR STRUCTURE PHOTOVOLTAIC DEVICES AND METHOD FOR MAKING THE SAME
Thin substrate photovoltaic and methods for making them are disclosed herein. In an embodiment, a photovoltaic device may include a substrate comprising a semiconductor material, one or more core structures, each extending essentially perpendicularly from a first surface of the substrate such that the core structures and the substrate form a single crystal, a shell layer disposed at least on a portion of a sidewall of the core structures and on the first surface, and a conductive layer disposed between adjacent core structures. The conductive layer forms an ohmic contact with the shell layer disposed on the first surface and between the adjacent core structures.
1 . A photovoltaic device comprising:
a substrate comprising a semiconductor material;
one or more core structures, each extending essentially perpendicularly from a first surface of the substrate such that the core structures and the substrate form a single crystal;
a shell layer disposed at least on a portion of a sidewall of the core structures and on the first surface; and
a conductive layer disposed between adjacent core structures,
wherein the conductive layer forms an ohmic contact with the shell layer.
2 . The photovoltaic device of claim 1 , wherein the substrate comprises one or more of a group IV single crystalline semiconductor, a group IV polycrystalline semiconductor, a group IV porous semiconductor, a single crystalline group III-V semiconductor, a single crystalline group II-VI semiconductor, and a single crystalline quaternary semiconductor.
3 . The photovoltaic device of claim 1 , wherein the substrate and at least one of the heavily doped semiconductor shell layer comprise one of the following doping profiles:
(i) the substrate is p type and the shell layer is n+type;
(ii) the substrate is n type and the shell layer is p+type.
4 . The photovoltaic device of claim 1 , wherein the one or more shell layers further comprise an optically transparent clad layer and a first layer.
5 . The photovoltaic device of claim 4 , wherein the each of the one or more core structures, the first layer comprising an intrinsic semiconductor, and the heavily doped semiconductor shell layer form a core-shell hetero-junction.
6 . The photovoltaic device of claim 4 , further comprising a second layer comprising a transparent conducting material disposed prior to disposing the optically transparent clad layer.
7 . The photovoltaic device of claim 1 , further comprising a first electrically conducting material disposed in electrical contact with the heavily doped semiconductor shell layer between neighboring core structures.
8 . The photovoltaic device of claim 1 , further comprising a second electrically conducting material disposed in electrical contact with a second surface of the substrate opposite the first surface.
9 . The photovoltaic device of claim 8 , further comprising a passivation layer disposed on the second surface of the substrate, wherein the passivation layer covers a portion of the second surface of the substrate not in contact with the second electrically conducting material.
10 . The photovoltaic device of claim 1 , wherein the substrate has a thickness of about 0.2 μm to about 50 μm.
11 . The photovoltaic device of claim 1 , wherein an aspect ratio of each of the one or more core structures is greater than one, aspect ratio being defined as a ratio of a dimension perpendicular to the substrate to a dimension parallel to the substrate.
12 . The photovoltaic device of claim 1 , wherein the one or more core structures have a cross-section including one or more of a circle, an ellipse, a convex polygon, and a mesh.
13 . The photovoltaic device of claim 1 , wherein neighboring core structures are separated by a distance of less than about 50 μm.
14 . A method of making a device, the method comprising:
obtaining a plurality of core structures, each extending essentially perpendicularly from a substrate such that the substrate and the plurality of core structures form a single crystal;
disposing a shell layer adjacent at least a portion of a sidewall of each of the plurality of core structures;
disposing a passivation layer substantially encapsulating the shell layer;
disposing a conductive layer between neighboring core structures substantially encapsulating the passivation layer; and
forming an ohmic contact between the conductive layer and the shell layer between the adjacent core structures by ablating the passivation layer using laser ablation.
15 . The method of claim 14 , wherein the substrate comprises one or more of a group IV single crystalline semiconductor, a group IV polycrystalline semiconductor, a group IV porous semiconductor, a single crystalline group III-V semiconductor, a single crystalline group II-VI semiconductor, and a single crystalline quaternary semiconductor.
16 . The method of claim 14 , wherein the substrate and the shell layer comprise one of the following doping profiles:
(i) the substrate is p type and the shell layer is n+type;
(ii) the substrate is n type and the shell layer is p+type.
17 . The method of claim 14 , wherein the substrate has a thickness of about 0.2 μm to about 50 μm.
18 . The method of claim 14 , wherein the shell layer comprises a heavily doped semiconductor shell layer.
19 . The method of claim 14 , wherein an aspect ratio of each of the one or more core structures is greater than one.
20 . The method of claim 14 , wherein the plurality of core structures have a cross-section including one or more of a circle, an ellipse, a convex polygon, and a mesh.
21 . The method of claim 14 , wherein the shell layer further comprises an optically transparent clad layer and a first layer.
22 . A method of making a photovoltaic device, the method comprising:
mounting on a first carrier substrate, a device substrate having a plurality of structures extending essentially perpendicularly from a first surface thereof;
disposing an ultra-violet (UV) removable adhesive on the device substrate such the plurality of structures and the first surface are substantially fully encapsulated by the UV removable adhesive;
contacting a second carrier substrate with the UV removable adhesive at a surface opposite the first surface;
unmounting the device substrate from the first carrier substrate to provide a second surface;
contacting the second surface with a conductive surface of a mounting surface; and
removing the second carrier substrate by exposing the UV removable adhesive to UV radiation.
23 . The method of claim 22 , wherein the second carrier substrate comprises glass.
24 . The method of claim 22 , wherein the device substrate comprises one or more of a group IV single crystalline semiconductor, a group IV polycrystalline semiconductor, a group IV porous semiconductor, a single crystalline group III-V semiconductor, a single crystalline group II-VI semiconductor, and a single crystalline quaternary semiconductor.
25 . The method of claim 22 , wherein each of the plurality of structures comprises a core-shell p-n junction configured to separate charge carriers in response to exposure to electromagnetic radiation.
26 . The photovoltaic device of claim 1 , wherein the shell layer is disposed on the first surface and between the adjacent core structures.
27 . The photovoltaic device of claim 1 , wherein the ohmic contact is between the adjacent core structures.
28 . The photovoltaic device of claim 1 , wherein the ohmic contact is only between the adjacent core structures.