High‐Throughput Screening of High‐Entropy Fluorite‐Type Oxides as Potential Candidates for Photovoltaic Applications

• Published in: Advanced energy materials 2023-06, Vol.13 (24), p.n/a
• Main Authors: Kumbhakar, Mukesh, Khandelwal, Anurag, Jha, Shikhar Krishn, Kante, Monaha Veerraju, Keßler, Pirmin, Lemmer, Uli, Hahn, Horst, Aghassi‐Hagmann, Jasmin, Colsmann, Alexander, Breitung, Ben, Velasco, Leonardo, Schweidler, Simon
• Format: Article
• Language: English
• Subjects: Cations; Cerium; Crystal structure; Electron mobility; Energy gap; Energy levels; Entropy; Fluorite; Hall‐effect measurements; high‐entropy materials; High‐throughput; Libraries; multicomponent materials; Oxidation; Oxides; photoelectron spectroscopy in atmosphere; Photovoltaic cells; Praseodymium; Reducing atmospheres; Solar cells; Synthesis; Terbium; UV–vis; Zirconium
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.202204337

High‐throughput (HT) synthesis and HT characterization techniques are becoming increasingly important due to the ever‐increasing complexity of materials and applications of advanced functional compounds. This work reports on the high‐throughput compilation of material libraries of high‐entropy oxides with fluorite crystal structure and tunable band gaps to be used as, e.g., semiconductors for photovoltaic applications. The material libraries cover the high‐entropy range of rare‐earth oxides with 5, 6, and 7 different cations (Ce, La, Sm, Pr, Tb, Y, and Zr) in near equimolar concentrations, but also the medium entropy range with 4 cations. The atmosphere used during or after synthesis is found to have a large effect on the band gap of these materials. Multivalent rare‐earth cations such as Ce/Pr/Tb enable reversible tuning of the band gap between 2.0 and 3.5 eV upon calcination under various oxidizing and reducing atmospheres. The high‐entropy fluorite oxides with smaller band gaps exhibit high electron mobility and transport energy levels compatible with common solar cell architectures. In this work, a time‐efficient investigation of rare‐earth fluorite‐type structured oxides with medium‐ and high‐entropy is presented. High‐throughput synthesis and automated characterization and analysis techniques provide a large data set that helps to select compositions to be studied for potential applications such as in solar cells or fuel cells.