Improved quantum yield and excellent luminescence stability of europium-incorporated polymeric hydrogen-bonded heptazine frameworks due to an efficient hydrogen-bonding effect

Two of the most persistent challenges for the high-end application of luminescent lanthanide (Ln) compounds are a low quantum yield and luminescence quenching caused by a liquid medium. In this work, a type of polymeric hydrogen-bonded heptazine framework is developed incorporating trivalent europium ions (P-HHF-Eu) via a low-cost and facile low-temperature thermal condensation reaction. Structural characterization clearly reveals that the solid-phase pyrolyzation reaction results in the formation of P-HHF-Eu. Using time-resolved and steady state photoluminescence (PL) spectroscopies, the photophysics and photochemistry of P-HHF-Eu at different hydration degrees are investigated and the role of hydrogen bonding in the significant enhancement of the emission properties is demonstrated. Furthermore, the P-HHF-Eu particles suspended in polyvinyl alcohol hydrogel exhibit excellent luminescence stability with a high PL quantum yield of up to approximate to 46% and wavelength responsive color-tunable emission, which holds potential for security applications.

Publication year:2020

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