Silver Zeolite Composites‐Based LEDs: A Novel Solid‐State Lighting Approach

Abstract

Silver clusters incorporated in a zeolite matrix represent a promising alternative for rare earth phosphors, organic dyes and quantum dots as emitters in organic and hybrid organic/inorganic light emitting diodes (OLEDs). Compared to other existing types of emitters they combine an excellent stability to oxygen and humidity with a high luminescence quantum yield and color tunability. This study reports on the first use of these silver exchanged zeolites embedded in polyvinyl carbazole (PVK), which was expected to act as a conducting matrix, as emitters in a single layer OLED. It is demonstrated that the introduction of these Ag-zeolites leads to electroluminescence bands that clearly differ from pristine PVK OLEDs as well as from the photoluminescence spectra of the Ag-zeolites. The current density and the spectral properties observed in these devices are strongly influenced by the zeolite silver loading, paving the way to a new type of easy tunable hybrid and cost effective OLEDs.

Supramolecular Organization in Confined Nanospaces

“…For example, the emission and excitation/absorption properties of rare‐earth or organic‐based phosphors appear still superior, as the Ag zeolites are normally activated with wavelengths below 350 nm and a wider excitation range would be preferable. On the bright side, besides outstanding luminescence, they display comparable quantum efficiencies, thermal behavior and also high stability . Actually, the zeolite confinement is very effective as a protective environment, but the composites still remain sensitive to humidity, that alters their photophysical properties.…”

“…On the bright side, besides outstanding luminescence, they display comparable quantum efficiencies, thermal behavior and also high stability. [445] Actually, the zeolite confinement is very effective as a protective environment, but the composites still remain sensitive to humidity, that alters their photophysical properties. Viable solutions may involve the embedding of Ag-loaded zeolites in polymeric matrices, or the sealing of the zeolite channel crystal terminations with functionalized stopcocks.…”

“…In zeolite A, the clusters are located in adjacent sodalite cages (Figure ), yet they still feature excellent stability and efficiency . By this virtue, silver exchanged LTA zeolites hold great promise for practical applications such as optical encoders or bright emitters in OLEDs . Further progress in this field could be triggered by deeper insight on the structural and electronic properties of the confined aggregates via first‐principles studies ,.…”

“…Although many approaches to the production of uniform, low-dimensionality nanostructures have been implemented over the years, [187,440] fabrication in confined spaces never lost its appeal. In particular, the improvement of synthesis and characterization techniques [441][442][443][444][445] combined with insight from computational studies [446][447][448] fostered this decade's tremendous progress. [43,449] Common synthetic strategies for confined nanoclusters are vapor deposition of suitable precursors, [14,16] or "ship-in-abottle" [450,451] approaches allowing for the in-situ synthesis of compounds in a host matrix.…”

“…[473] By this virtue, silver exchanged LTA zeolites hold great promise for practical applications such as optical encoders [444] or bright emitters in OLEDs. [445] Further progress in this field could be triggered by deeper insight on the structural and electronic properties of the confined aggregates via first-principles studies. [447,474] Also, since silver cations located at different sites have different enthalpies of adsorption, [475,476] the use of thermodynamic models capable to predict the repartition of Ag + cations in the confining medium upon ion exchange, and hence the organization of the Agclusters in the final composite, could advance the preparation procedures of these materials via a knowledge-based approach.…”