Improved photoluminescence and ferroelectric properties of (Bi_3.6Eu_0.4)Ti₃O₁₂thin films via Li⁺doping

Abstract

(Bi(3.6)Eu(0.4))Ti₃O₁₂ (BEuT) thin films with different Li+ doping contents were prepared on fused silica and Pt/Ti/SiO₂/Si substrates by chemical solution deposition, and the effects of Li+ doping contents on the photoluminescence and ferroelectric properties of the thin films were investigated in detail. The results showed that an appropriate amount of Li+ doping could effectively improve emission intensities for two characteristic Eu³+ emission transitions of ⁵D₀→⁷F₁ (594 nm) and ⁵D₀→⁷F₂ (617 nm) compared with BEuT thin films without Li doping. This photoluminescence improvement can be attributed to the dual roles of Li+ ions, one of which is that Li ions can act as co-activators which are helpful to the energy transfer from the host to the Eu³+ ions, leading to a higher quantum yield; the other is that Li ion doping can induce local distortion of crystal field surrounding the Eu³+ activator because Bi³+ and Li+ ions have different ionic radii. In addition, the Li+-doped BEuT thin films had larger remanent polarization than BEuT thin films without Li doping prepared under the same experimental conditions. These results suggest that Li+ doping is an effective way to improve photoluminescence and ferroelectric properties of the (Bi,Eu)₄Ti₃O₁₂ thin films.

Improved Red Photoluminescence and Ferroelectricity in Layered Composite (Bi,Eu)4Ti3O12/ZnO Thin Films

“…For example, (Bi,Eu) 4 Ti 3 O 12 (BEuT) thin films were reported to show red photoluminescence properties of Eu 3þ ions, which might have potential applications for integrated photoluminescent ferroelectric thin-film devices. 9,10) However, the emission intensity of BEuT thin films needs further improvement. 11) Considering that there is possibly an efficient energy transfer from ZnO to Eu 3þ ions in the host lattices, 12,13) and ZnO layer can act as a buffer layer to promote crystallization or tune electrical properties of ferroelectric films, 14,15) constituting layered composite BEuT/ZnO thin films should be an effective way to enhance the photoluminescence of Eu 3þ ions in BEuT.…”