Light harvesting architectures for electron beam evaporated solid phase crystallized Si thin film solar cells: Statistical and periodic approaches

Abstract

The fabrication of light trapping architectures for electron beam (e-beam) evaporated polycrystalline Si thin film solar cells is investigated based on tailored self-organized light scattering silica nanospheres and 2 dimensional periodic nanoimprinted structures on glass. A microscopic analysis reveals a unique correlation between the microstructure of high-rate e-beam evaporated Si and the substrate topography. These features provide the basis for the design of nanostructured Si that complies with its distinctive growth characteristics. A layer of self-organized nanospheres embedded in a sol–gel matrix and an anti-reflection coating is found to be an e-beam compatible light trapping approach for poly-Si solar cells, contributing to an increase of 50% in current collection. We developed a preparation process for arrays of equidistant free-standing Si crystals with remarkable optical absorption characteristics based on a nanoimprinted glass substrate by selectively etching e-beam evaporated Si. This periodic approach opens design possibilities for effective three-dimensional architectures for advanced photon management.