title: Two- and three-dimensional folding of thin film single-crystalline silicon for photovoltaic power applications.
abstract: Fabrication of 3D electronic structures in the micrometer-to-millimeter range is extremely challenging due to the inherently 2D nature of most conventional wafer-based fabrication methods. Self-assembly, and the related method of self-folding of planar patterned membranes, provide a promising means to solve this problem. Here, we investigate self-assembly processes driven by wetting interactions to shape the contour of a functional, nonplanar photovoltaic (PV) device. A mechanics model based on the theory of thin plates is developed to identify the critical conditions for self-folding of different 2D geometrical shapes. This strategy is demonstrated for specifically designed millimeter-scale silicon objects, which are self-assembled into spherical, and other 3D shapes and integrated into fully functional light-trapping PV devices. The resulting 3D devices offer a promising way to efficiently harvest solar energy in thin cells using concentrator microarrays that function without active light tracking systems.
authors.affiliation: Frederick Seitz Materials Research Laboratory, Department of Materials Science, University of Illinois, Urbana, IL 61801, USA.
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Guo
authors.forename: Huan
authors.initials: H
authors.lastname: Li
authors.forename: Bok Yeop
authors.initials: BY
authors.lastname: Ahn
authors.forename: Eric B
authors.initials: EB
authors.lastname: Duoss
authors.forename: K Jimmy
authors.initials: KJ
authors.lastname: Hsia
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Lewis
authors.forename: Ralph G
authors.initials: RG
authors.lastname: Nuzzo
mesh_terms: D004563:Electrochemistry / Q000295:instrumentation* / Q000379:methods; D010777:Photochemistry / Q000295:instrumentation* / Q000379:methods; D012825:Silicon / Q000737:chemistry*; D012993:Solar Energy
chemical_list: D012825:Silicon