A facile neoteric technique to achieve [SrF2:Eu3+@SiO2]//[SrF2:Tb3+@SiO2] Janus yolk–shell nanofibers with ideal white-light emission via triple-inhibiting energy transfer between Tb3+ and Eu3+ ions†

Phosphors mostly emit yellow-color fluorescence when intensely luminous Tb³⁺ and Eu³⁺ are directly co-doped in hosts due to energy transfer (ET) from Tb³⁺ to Eu³⁺; therefore, it is hard to achieve white-light emission. To solve this problem, we propose a triple-inhibiting effect strategy to totally inhibit ET between Tb³⁺ and Eu³⁺via a rationally designed one-dimensional nanostructure to achieve ideal white-light emission. As a case study, [SrF₂:Eu³⁺@SiO₂]//[SrF₂:Tb³⁺@SiO₂] Janus yolk–shell nanofibers (JYSNFs) are designed and conveniently constructed by combining di-axis parallel electrospinning with bi-crucible fluorination technology to avoid complex synthetic processes. The Janus yolk–shell nanofiber is formed by two parallel-bound yolk–shell nanofibers, and thus, six functional partitions in the Janus yolk–shell nanofiber are realized. The Janus yolk–shell nanofiber structure confines Tb³⁺ and Eu³⁺ in their respective core layers with protection and isolation of outer-layer SiO₂ and voids to achieve a triple-inhibiting effect to fully avoid ET between Tb³⁺ and Eu³⁺, realizing ideal white-light emission and tunable luminescence of JYSNFs. The design concept and technology provide theoretical and technical support for developing a new type rare earth luminescent materials by prohibiting ET between activators. The Janus yolk–shell nanofiber with six partitions is extended to achieve poly-functions via shunning baleful mutual interferences among various functions.