Nano-imprint lithography for advanced light management concepts in multi-junction solar cells

Nano-imprint lithography is a versatile tool for the realization of light management textures in photovoltaic devices. Various types of nano-structures of variable geometries and arrangements can be fabricated using this technology. In this contribution, we show how to apply nano-imprint lithography at different levels in the fabrication chain of thin-film silicon solar cells. For the realization of advanced light management concepts it is necessary to texture the front- and backside of a solar cell device or the intermediate reflector in a tandem solar cell structure. Two examples of advanced light management concepts for thin-film silicon tandem solar cells are shown in this study. In the first example periodic light trapping structures are applied at the front-side of the solar cell device which results in a higher conversion efficiency driven by an increased short-circuit current. In the second example the intermediate reflector of the solar cell is textured by a nano-imprint process, such that two different light-trapping textures are used for the top cell and the bottom cell of the tandem photovoltaic device. With this work we show how the fabrication of advanced light management concepts can benefit from an industrial relevant nano-imprint process.