Confinement of Highly Luminescent Lead Clusters in Zeolite A

Abstract

Metal clusters confined inside zeolite frameworks display unique electronic, catalytic, and optical properties. However, so far only confined silver clusters have shown peculiar luminescent properties, displaying high photoluminescent quantum efficiencies reaching almost unity. In this study, we demonstrate the self-assembly and confinement of highly luminescent lead (Pb) clusters into the molecular-sized cavities of Linde Type A (LTA) zeolites. These Pb-LTA samples display an intense deep-blue emission with external quantum efficiencies up to 69% in their partially dehydrated state. A tetrahedral lead cluster (Pb 4 ) with unusually short Pb−Pb distances and hydroxyl ligands was identified as responsible for the luminescence as determined by X-ray absorption fine structure (XAFS) analysis. The in-depth characterization of the Pb-zeolites, reported here, sets the stage for elucidating the structure-to-luminescent relationship of other zeolite-embedded clusters.

Luminescent silver–lithium-zeolite phosphors for near-ultraviolet LED applications

“…TGA reveals three main regions of dehydration as previously reported for other LTA samples. 8,24 The third and final desorption peak in Li-LTA is however strongly shifted compared to that of other LTA samples to about 400 °C compared to 250 °C for the others. This shift can be related to the large hydration enthalpy of the Li-ions, 37 whereby the final dehydration starting near 350 °C has a very strong impact on the luminescent properties of the samples.…”

“…Finally, the sample was calcined in a muffle oven as reported elsewhere. 24 In a next step, Ag + was exchanged into fully Li-exchanged LTA (Li-LTA) zeolites using the procedure reported by Fenwick et al, 3 to obtain a sample with an Ag1Li11Si12Al12O48 (Ag1 Li-LTA) composition.…”

Tunable white emission of silver-sulfur-zeolites as single-phase LED phosphors

“…For the case of luminescent metal exchanged zeolites, especially Ag-exchanged zeolites, large Stokes shifts combined with high extinction coefficients and high quantum efficiencies have been reported [16][17][18][19][20], making them suitable candidates to overcome the difficulties encountered in remote-phosphors LEDs [6,21]. Nevertheless, these silver clusters (Ag-CLs) confined in zeolites tend to display only broad singlecolor emission and up till now, no high efficient red emission has been reported for these materials.…”

Shaping the Optical Properties of Silver Clusters Inside Zeolite A via Guest–Host–Guest Interactions

“…Most often only 1 out of 12 counterbalancing cations was replaced with Ag + based on the report by Coutino-Gonzalez et al 11 which showed that Ag 1 -exchanged LiNa-LTA samples (33% Li + ) display the highest external quantum efficiency (EQE). Finally, the samples were thermally activated 24 to form AgCLs and were hydrated in a closed container with a relative humidity of 99%, using a saturated K 2 SO 4 solution (Sigma-Aldrich, ≥ 99%).…”