Semiconducting Electrides Derived From Sodalite: A First-principles Study

TL;DR

This study uses first-principles calculations to design semiconducting electrides derived from sodalite structures, identifying a promising candidate with a suitable band gap for photocatalysis.

Contribution

It introduces a novel approach to design semiconducting electrides from complex minerals, expanding the understanding and potential applications of these materials.

Findings

Identified a cubic Ca4Al6O12 structure with a 1.2 eV band gap

Demonstrated electron localization in sodalite cages

Showed cation electronegativity influences electride formation

Abstract

Electrides are ionic crystals with electrons acting as anions occupying well-defined lattice sites. These exotic materials have attracted considerable attention in recent years for potential applications in catalysis, rechargeable batteries, and display technology. Among this class of materials, electride semiconductors can further expand the horizon of potential applications due to the presence of a band gap. However, there are only limited reports on semiconducting electrides, hindering the understanding of their physical and chemical properties. In a recent work, we initiated an approach to derive potential electrides via selective removal of symmetric Wyckoff sites of anions from existing complex minerals. Herein, we present a follow-up effort to design the semiconducting electrides from parental complex sodalites. Among four candidate compounds, we found that a cubic Ca$_4$Al$_6$O$_{12}$ structure with the $I$-43$m$ space group symmetry exhibits perfect electron localization at the sodalite cages, with a narrow electronic band gap of 1.2 eV, making it suitable for use in photocatalysis. Analysis of the electronic structures reveals that a lower electronegativity of surrounding cations drives greater electron localization and promotes the formation of an electride band near the Fermi level. Our work proposes an alternative approach for designing new semiconducting electrides under ambient conditions and offers guidelines for further experimental exploration.