Textured superstrates for photovoltaics

Abstract

Textured superstrates for photovoltaic cells, for example, silicon tandem photovoltaic cells with light scattering properties which are sufficient for light trapping independent of wavelength are described herein. Features of a textured surface of a superstrate, via the method(s) used to make the textured superstrate, can be tailored to provide the desired light scattering / trapping properties. The method includes grinding and lapping or grinding, lapping, and etching of a glass superstrate.

Description

[0001] This application claims priority to US Provisional Application No. 61 / 264929, filed November 30, 2009, and US Application No. 12 / 955126, filed November 29, 2010. [0002] background technical field [0003] Embodiments relate generally to photovoltaic cells, and more particularly to light scattering textured superstrates and methods of making light scattering textured superstrates for use in, for example, silicon based photovoltaic cells. Background technique [0004] An important property of solar cells of any configuration is efficiency; that is, the energy produced per unit area under standard solar illumination. It is this characteristic that determines the final cost per watt. The theoretical efficiency of a dual (or tandem) structure with amorphous and microcrystalline silicon is believed to be superior to a single cell based on amorphous or microcrystalline silicon. The advantage of using both amorphous silicon and microcrystalline silicon in a tandem structu...

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Problems solved by technology

[0011] Textured TCO technology may include one or more of the following disadvantages: 1) the rough structure of the texture can degrade the quality of the deposited silicon, causing electrical shorts, thereby reducing the overall performance of the solar cell; Optimization is also limited by the texture that can be formed by the deposition or etching process and the reduction in light transmission associated with thicker TCO layers; and 3) in the case of ZnO, the use of plasma treatment or wet etching to create the texture increases the cost

[0015] Textured glass substrate methods may include one or more of the following disadvantages: 1) sol-gel chemistry and related processes need to provide bonding of glass microspheres to the substrate; 3) additional costs associated with silica microspheres and sol-gel materials; and 4) problems with film adhesion and / or crack formation in silicon films

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