Seán Kavanagh1,2,Irea Mosquera-Lois2,Aron Walsh2,David Scanlon1
University College London1,Imperial College London2
Seán Kavanagh1,2,Irea Mosquera-Lois2,Aron Walsh2,David Scanlon1
University College London1,Imperial College London2
Point defects are a universal feature of crystalline materials, dictating the functional performance of materials across a wide range of applications (transistors, thermoelectrics, LEDs, power electronics, transparent conductors, photovoltaics…). The standard approach of simulating defects is, however, prone to miss the ground state atomic configurations associated with energy-lowering reconstructions from the high-symmetry crystal environment.<sup>1–5</sup> By yielding both incorrect energies and structures, this failing of current defect calculation approaches compromises the accuracy of calculated properties and behaviour of defects in semiconductors.<br/><br/>To address this issue, we report an approach to efficiently navigate the defect configurational landscape using targeted bond distortions and rattling.<sup>6</sup> Application of our workflow to a range of materials (ranging from perovskites to conventional semiconductors) reveals symmetry breaking in each material that is not found via conventional local minimization techniques. We demonstrate the impact of these reconstructions on derived properties, including formation energies, concentrations and charge transition levels of defects in perovskite materials and beyond.<br/><br/>1. Arrigoni, M. & Madsen, G. K. H. Evolutionary computing and machine learning for discovering of low-energy defect configurations. <i>npj Comput Mater</i> <b>7</b>, 1–13 (2021).<br/>2. Mosquera-Lois, I. & Kavanagh, S. R. In search of hidden defects. <i>Matter</i> <b>4</b>, 2602–2605 (2021).<br/>3. Lany, S. & Zunger, A. Metal-Dimer Atomic Reconstruction Leading to Deep Donor States of the Anion Vacancy in II-VI and Chalcopyrite Semiconductors. <i>Phys. Rev. Lett.</i> <b>93</b>, 156404 (2004).<br/>4. Kavanagh, S. R., Walsh, A. & Scanlon, D. O. Rapid Recombination by Cadmium Vacancies in CdTe. <i>ACS Energy Lett.</i> <b>6</b>, 1392–1398 (2021).<br/>5. Kavanagh, S. R., Scanlon, D. O., Walsh, A. & Freysoldt, C. Impact of metastable defect structures on carrier recombination in solar cells. <i>Faraday Discuss.</i> (2022) doi:10.1039/D2FD00043A.<br/>6. Mosquera-Lois, I., Kavanagh, S. R., Walsh, A., Scanlon, D. O. Symmetry-breaking and reconstruction at point defects in solids. <i>npj Computational Materials </i>(In submission; https://doi.org/10.48550/arXiv.2207.09862)<br/>7. Mosquera-Lois, I., Kavanagh, S. R., Walsh, A., Scanlon, D. O. ShakeNBreak: Efficiently navigating the defect configurational landscape. <i>J Open Source Software </i>(In submission; https://github.com/SMTG-UCL/ShakeNBreak)