XANES reveals Mn2+ and Mn3+ coexistence in Persistent Luminescence Mn-doped halide double perovskites
Emmanuela Di Giorgio a, Francesca Cova b, Marta Campolucci a, Chiara Solinas a, Mauro Fasoli b, Alberto Martinelli c, Blanka Detlefs d, Pieter Glatzel d, Federico Locardi a
a Department of Chemistry and Industrial Chemistry, University of Genoa, Via Dodecaneso 31, 16146 Genova, Italy
b Department of Materials Science, University of Milano - Bicocca, Via Cozzi 55, 20125 Milano, Italy
c CNR-SPIN, Corso F. Perrone, 16152 Genova, Italy
d ESRF – The European Synchrotron, 71 Avenue des Martyrs, 38000 Grenoble, France
Proceedings of MATSUS Spring 2026 Conference (MATSUSSpring26)
C1 Structural Foundations of Nanomaterials Properties
Barcelona, Spain, 2026 March 23rd - 27th
Organizers: Nicola Dengo, Nadine Schrenker and Stefano Toso
Poster, Emmanuela Di Giorgio, 907
Publication date: 15th December 2025

Persistent luminescence materials (PeLMs) have attracted significant attention due to their ability to store excitation energy and release it gradually as light over extended periods (from minutes to several weeks) after the excitation source is removed. These materials are widely investigated for applications like emergency signals, road markings, bioimaging, photocatalysis, optical storage and anti-counterfeiting technologies [1], [2], [3], [4]. For most of these applications, the use of PeLMs nanocrystals is preferable. However, the downscaling of PeLMs often has a detrimental effect on the persistent luminescence (PeL) observable at room temperature [5]. In this work, we investigated Mn-doped halide double perovskites in single crystals (SCs) and nanocrystals forms through X-ray Absorption Near Edge Spectroscopy (XANES). The study was specifically designed to elucidate the oxidation state distribution of Mn and its dependence on crystal size and its influence on PeL. In particular, we focused on two compositions: Cs2NaInCl6:Mn (hereafter Ag0) and Cs2Na0.2Ag0.8InCl6:Mn (Ag0.8). These stoichiometries allow to explore the influence of partial substitution of Na+ with Agon the local electronic structure of Mn and, consequently, on macroscopic PeL-related properties. In both compositions (Ag0 and Ag0.8), XANES revealed the coexistence of Mn2+ and Mn3+ species for SCs and only Mn2+ for nanocrystals (both nanocubes – NC and nanoplates – NP), highlighting a mixed-valence scenario that is common in other PeLMs, like SrAl2O4: Eu2+, Dy3+ [6]. These results contribute to the broader understanding of how compositional modifications can be exploited to optimize PeL properties in emerging perovskite-based materials and beyond.

XANES spectroscopy was carried out at ID26 beamline (DOI: 10.15151/ESRF-ES-1934082974) of the European Synchrotron (ESRF; Grenoble, France), with beamtime HC5985.

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