Four-electron negative-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>U</mml:mi></mml:math> vacancy defects in antimony selenide

Abstract

Negative-$U$ defects in solids break the assumption that like charges repel. The standard negative-$U$ model describes the favorable attraction of a second electron to a defect centre. Here, the authors demonstrate an extension of negative-$U$ behavior up to a change of four electrons. This occurs for the emerging photovoltaic compound Sb${}_{2}$Se${}_{3}$. The phenomenon is explained as a special case of valence alternation arising from the large change in structure and bonding that accompanies electron capture.

Topics & Concepts