Low-energy silicon allotropes with strong absorption in the visible for photovoltaic applications

TL;DR

This paper reports on novel silicon allotropes with lower formation energy and strong visible light absorption, making them promising candidates for efficient thin-film solar cells.

Contribution

The study introduces new silicon phases with unique electronic and optical properties, characterized by first-principles calculations, that outperform existing silicon structures for photovoltaic use.

Findings

Some allotropes have quasi-direct, dipole-allowed band gaps (0.8-1.5 eV)

Absorption coefficients comparable to chalcopyrites used in record solar cells

Lower formation energy than other experimentally realized silicon phases

Abstract

We present state-of-the-art first-principle calculations of the electronic and optical properties of silicon allotropes with interesting characteristics for applications in thin-film solar cells. These new phases consist of distorted sp$^3$ silicon networks and have a lower formation energy than other experimentally produced silicon phases. Some of these structures turned out to have quasi-direct and dipole-allowed band gaps in the range 0.8--1.5\,eV, and to display absorption coefficients comparable with those of chalcopyrites used in thin-film record solar cells.