Regensburg 2025 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
O: Fachverband Oberflächenphysik
O 92: Electronic Structure Theory
O 92.11: Talk
Thursday, March 20, 2025, 17:30–17:45, H25
Electronic and optical properties of computationally predicted Na-K-Sb crystals — •Chung Xu, Richard Schier, and Caterina Cocchi — University of Oldenburg
Due to their favorable electronic and optical properties, sodium-potassium-antimonides are an emerging class of crystals used as photocathodes in particle accelerators. Using first-principles methods based on density-functional theory and many-body perturbation theory, we investigate the electronic and optical properties of cubic NaK2Sb and hexagonal Na2KSb, two computationally predicted polymorphs of established photocathode materials that can emerge as metastable phases in polycrystalline samples. Our results indicate that both systems are indirect band-gap semiconductors with fundamental gaps on the order of 0.7 and 0.8 eV, respectively. Their direct gaps are very close to these values and Their optical spectra are characterized by weakly bound excitons in the near-infrared region which represent favorable characteristics for efficient photoemission. Our study suggests that the presence of cubic NaK2Sb and hexagonal Na2KSb in photocathode samples is not detrimental for their application as photocathodes [1].
[1] arXiv:2411.13330
Keywords: photocathode; multi-alkali antimonides; photovoltaics