Discovery and Engineering of Low Work Function Perovskite Materials

TL;DR

This study uses computational screening to identify stable, low work function perovskite oxides, revealing key chemistry insights and proposing promising materials for electron emission applications.

Contribution

It provides a large-scale DFT screening of over 2900 perovskites, identifying seven promising low work function compounds and elucidating chemistry trends affecting work function values.

Findings

Seven promising low work function perovskites identified

Materials with barely filled d bands have lowest work functions

Database of work functions aids in device engineering

Abstract

Materials with low work functions are critical for an array of applications requiring the facile removal or efficient transport of electrons through a device. Perovskite oxides are a promising class of materials for finding low work functions, and here we target applications in thermionic and field electron emission. Perovskites have highly malleable compositions which enable tunable work function values over a wide range, robust stability at high temperatures, and high electronic conductivities. In this work, we screened over 2900 perovskite oxides in search of stable, conductive, low-work-function materials using Density Functional Theory (DFT) methods. Our work provides insight into the materials chemistry governing the work function value of a perovskite, where materials with barely filled d bands possess the lowest work functions. Our screening has resulted in a total of seven promising compounds, such as BaMoO3 and SrNb0.75Co0.25O3 with work functions of 1.1 eV and 1.5 eV, respectively. These promising materials and others presented in this study may find use as low work function electron emitters in high power vacuum electronic and thermionic energy conversion devices. Moreover, the database of calculated work functions and materials chemistry trends governing the value of the work function may aid in the engineering of perovskite heterojunction devices.