Template for three-dimensional thin-film solar cell manufacturing and methods of use
A template 100 for three-dimensional thin-film solar cell substrate formation for use in three-dimensional thin-film solar cells. The template 100 comprises a substrate which comprises a plurality of posts 102 and a plurality of trenches 104 between said plurality of posts 102 . The template 100 forms an environment for three-dimensional thin-film solar cell substrate formation.
1. A structure for use in the fabrication of a photovoltaic solar cell, said structure comprising;
a reusable monocrystalline silicon template;
a substantially conformal sacrificial porous silicon layer coupled to said reusable template; and
an epitaxial three-dimensional monocrystalline silicon thin-film solar cell substrate deposited on said conformal sacrificial porous silicon layer; wherein
said reusable template has an area at least as large as an area of said three-dimensional monocrystalline silicon thin-film solar cell substrate, said three-dimensional monocrystalline silicon thin-film solar cell substrate measuring at least 125 mm×125 mm, said reusable template having an array of structural surface topography features substantially conforming to desired structural surface topography features of said three-dimensional monocrystalline thin-film solar cell substrate; and further wherein
a first subset of said structural surface topography features are positioned at predetermined locations on said template and comprise a plurality of discrete and isolated hexagonal posts defined by sidewalls and having a central axis positioned substantially perpendicular to a top surface of said reusable template, said discrete and isolated hexagonal posts associated with a set of geometrical aspect ratios and dimensions comprising a ratio between height and hexagonal diagonal dimension approximately in the range of 0.5 to 5.0; and
a second subset of said structural surface topography features are positioned at predetermined locations on said template and comprise a plurality of interconnected continuous trenches interspersed among and bordering said plurality of discrete and isolated hexagonal posts and having a trench bottom width ranging at least approximately between 1 to 30 microns;
said three-dimensional monocrystalline silicon thin-film solar cell substrate having a surface topography defined by said first and said second subset of said structural surface topography features of said reusable template;
said reusable template, said first subset of said structural surface topography features, and said second subset of said structural surface topography features cooperating to ensure that said three-dimensional monocrystalline silicon thin-film solar cell substrate is capable of being detached from said reusable template as a free-standing, self-supporting substrate with sufficient mechanical rigidity and resilience for processing in a solar cell manufacturing environment; and
said reusable template further configured to form in said three-dimensional monocrystalline silicon thin-film solar cell substrate a sunlight capturing surface structure for enabling high solar cell conversion efficiencies.
2. The structure of claim 1 , wherein said sidewalls of said hexagonal posts are tapered sidewalls with sidewall angles in the range of 0° to 10°.
3. The structure of claim 1 , wherein said plurality of interconnected continuous trenches further comprise backside holes providing access to said trenches from a backside of said template.
4. The structure of claim 1 , wherein said plurality of interconnected continuous trenches are through-wafer trenches.
5. The structure of claim 1 , wherein said set of geometrical aspect ratios comprise a ratio between height and hexagonal diagonal dimension are approximately in the range of 1 to 3.