Inside the structure of Mn2+ doped Cs2(Na1-xAgx)InCl6 persistent luminescence compounds

This study focuses on Mn-doped halide double perovskites (HDPs) with persistent luminescence (PeL), in both bulk and nanocrystal forms. Currently, PeL materials are commercially used in toys or emergency signals, but their potential applications extend to areas such as road markings, photocatalysis, biomedicine, and solar energy. Cs₂(Na₁₋ₓAgₓ)InCl₆:Mn²⁺ is a high emissive material both in bulk (single crystals – SC) and at the nanoscale (nanoplates - NP; nanocubes – NC); moreover, the bulk material possesses a PeL measurable for hours. Surprisingly, at RT the PeL disappears in nanocrystals while they retain a considerable photoluminescence. Even if several hypotheses have been proposed, the cause of this behaviour remains unexplained. PeL is caused by traps, which could be local structural defects. So, we investigate these defects with X-ray Powder Diffraction, Pair Distribution Function analysis and X-ray Absorption Near Edge Structure spectroscopy. In this work, we present data on crushed single crystals and nanocrystals of Cs₂(Na0.2Ag0.8)InCl6:Mn2+, exploring the influence of size.