Dramatically Enhanced Luminescence of Layered Terbium Hydroxides as Induced by the Synergistic Effect of Gd³⁺ and Organic Sensitizers

Abstract

Host–guest chemistry allows the engineering of new functional materials with tunable properties. This study focuses on layered terbium hydroxides (NO3-LTbH) codoped with Gd3+ (NO3-LTbH:Gd), which were prepared using the hydrothermal method and successfully modified using sensitizers (L). Luminescence studies showed that compared with the NO3-LTbH precursor the sensitizer-modified NO3-LTbH:Gd exhibited high luminescence intensity and high luminescence quantum efficiency (Φ = 33%). This performance results from the synergistic effect of codoped Gd3+ and intercalated sensitizers in the organic–inorganic hybrid materials, which led to stronger luminescence properties, and synergistic effect on the enhancement of Tb3+ luminescence was investigated by the spectroscopic characteristics, UV–vis absorption spectrum, low-temperature phosphorescence, and crystal structures of the layered rare-earth hydroxides. Studies demonstrate that the mechanism for synergistic effect of significant enhancement of Tb3+ luminescence is mainly caused by Gd3+ inducing a cascaded energy transfer from the host to Tb3+ via organic sensitizers. The very interesting thing is that LTbH:Gd has multiple roles, including energy-transfer bridges that connect the sensitizers and Tb3+ (in host) to enhance the characteristic emission of Tb3+, significantly enhancing phosphorescence of sensitizers, and acting as host matrices for sensitizers. Second, the effects of intercalation conditions on luminescence were also investigated. Furthermore, a novel transparency luminescent composite film device [PMMA/L-LTbH:Gd] that exhibits strong luminescence property was also fabricated using the solvent-casting method.