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Low-density silicon allotropes for photovoltaic applications

Authors: Maximilian Amsler, Silvana Botti, M.A.L. Marques, Thomas J. Lenosky, and Stefan Goedecker

Ref.: Phys. Rev. B 92, 014101 (2015)

Abstract: Silicon materials play a key role in many technologically relevant fields, ranging from the electronic to the photovoltaic industry. The environmental challenges awaiting in the 21st century through global climate change and limited supply of fossil energy demands for the development of novel materials with improved absorption in the visible to harvest solar energy with higher efficiency. In this article we present the results of a systematic search for unknown silicon allotropes by using the ab initio minima hopping crystal structure prediction method to explore the hitherto barely explored low-density regime of the silicon phase diagram. In total 11 metastable phases are identified with direct or quasi-direct band-gaps in the range of ≈ 1.0-1.8 eV, close to the optimal Shockley-Queisser limit of ≈ 1.4 eV, with a stronger overlap of the absorption spectra with the solar spectrum compared to conventional diamond silicon. Due to the strong structural resemblance to known clathrate compounds it is expected that the predicted phases can be synthesized.

Citations: (Google scholar)

DOI: 10.1103/PhysRevB.92.014101

URL: arxiv.org