Tetraphenylethylene-based Eu3+-metallopolymers with aggregation-enhanced white emission for self-calibrating temperature sensing and white light-emitting diodes (WLEDs)

Abstract

In this work, through the ternary copolymerization reaction between VTPY (4′-(4-((4-vinylbenzyl)oxy)phenyl)-2,2′:6′,2′′-terpyridine), VTPE ((2-(4-vinylphenyl)ethene-1,1,2-triyl)tribenzene) and MMA (methyl methacrylate), the polymer platform poly(VTPY-co-VTPE-co-MMA) was successfully synthesized, further based on the coordination reaction between poly(VTPY-co-VTPE-co-MMA) and Eu(TTA)₃·2H₂O (TTA: 2-thenoyltrifluoroacetone), poly-Eu(TTA)₃ (1–3) that can emit tunable multicoloured photoluminescence including white light emission were finally fabricated. Interestingly, owing to the strong blue-green emission from the aggregation-induced emission (AIE) active VTPE unit, as well as the highly efficient sensitized red emission from the Eu³⁺ ion, the white light emitting poly-Eu(TTA)₃ (2) exhibited an outstanding fluorescence quantum yield of 51.99%; more significantly, it also showed reversible temperature-dependent emission within the temperature range from 313 K to 383 K, with a high relative temperature sensitivity of 5.16% K⁻¹ at 383 K, and an excellent temperature resolution of 0.03 K. Finally, by combining poly-Eu(TTA)₃ (2) with an n-UV LED chip, a white light LED device with a high Ra of 86.1, R9 of 89.8 and relatively low CCT of 6201 K was successfully fabricated. These results not only provide a feasible and promising way for the synthesis of high-efficiency white light emitting Eu³⁺-metallopolymers, but also expanded their possibility for the development of ratiometric temperature sensors and white light emitting diodes.