Towards Direct-Gap Silicon Phases by the Inverse Band Structure Design Approach

TL;DR

This paper introduces an inverse band structure design method using particle swarm optimization to discover silicon phases with improved optical properties, aiming to enhance solar cell efficiency.

Contribution

A novel inverse-band structure design approach is developed to predict metastable silicon phases with better optical properties than diamond silicon.

Findings

Predicted a cubic Si20 phase with a quasi-direct gap of 1.55 eV

Demonstrated potential for improved thin-film solar cells

Introduced a new computational method for material discovery

Abstract

Diamond silicon (Si) is the leading material in current solar cell market. However, diamond Si is an indirect band gap semiconductor with a large energy difference (2.4 eV) between the direct gap and the indirect gap, which makes it an inefficient absorber of light. In this work, we develop a novel inverse-band structure design approach based on the particle swarming optimization algorithm to predict the metastable Si phases with better optical properties than diamond Si. Using our new method, we predict a cubic Si20 phase with quasi-direct gaps of 1.55 eV, which is a promising candidate for making thin-film solar cells.