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  • Tutorial
  • Open Access

Beginner’s Guide to Interpreting Defect and Defect Level Diagrams

Prashun Gorai*

  • *Contact author: goraip@rpi.edu
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PRX Energy 4, 032001 – Published 22 August, 2025

DOI: https://doi.org/10.1103/jtyg-xry3

Abstract

Point defects are ubiquitous in materials and play a critical role in determining their electrical, optical, ion-transport, and other properties, making them key to the performance of materials in energy applications. First-principles defect calculations, particularly those based on density functional theory, are powerful tools for predicting defect energetics and associated electronic properties. However, the results are often communicated through defect formation energy diagrams and defect level diagrams, which can be challenging to interpret for researchers who do not specialize in defect physics. This Tutorial provides a practical accessible guide for understanding and interpreting these diagrams, with a focus on materials with a band gap—semiconductors and insulators. Aimed at experimentalists and computationalists new to defect analysis, the Tutorial explains how to extract key physical insights from defect diagrams, such as defect and carrier concentrations, dopability, midgap states, and charge localization. By demystifying the language and visuals of defect calculations, this guide seeks to bridge the gap between theory and experiments, enabling broader use of defect data in the rational design of functional materials for energy applications and beyond.

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Popular Summary

Point defects are imperfections in a material's crystal structure that can dramatically impact its electrical, optical, and transport properties. These defects are central to the performance of semiconductors and energy materials yet understanding them often requires specialized knowledge. This Tutorial addresses a common barrier: the difficulty in interpreting defect formation energy and level diagrams, which are widely used in computational studies of materials. Designed for both experimentalists and newcomers to defect calculations, this guide explains how to read these diagrams and extract physical insights about dopability, defect and carrier concentrations, midgap states, and charge localization. It also highlights common misconceptions and points to important methodological considerations. By bridging the gap between complex computational outputs and practical interpretation, this Tutorial enables a broader community of researchers to use defect calculations in designing advanced materials. The goal is to make defect physics more accessible and its applications more impactful across the energy field and beyond.

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PRX Energy 4, 032001– Published 22 August, 2025
  • Received 20 June 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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