Significantly Enhanced Red Photoluminescence Properties of Nanocomposite Films Composed of a Ferroelectric Bi3.6Eu0.4Ti3O12 Matrix and Highly c-Axis-Oriented ZnO Nanorods on Si Substrates Prepared by a Hybrid Chemical Solution Method

Abstract

We have developed a hybrid chemical solution method for preparing nanocomposite thin films composed of a ferroelectric Bi_3.6Eu_0.4Ti₃O₁₂ (BEuT) matrix and highly c-axis-oriented ZnO nanorods on Si substrates. First, a seed-layer solution growth approach was used to prepare the highly c-axis-oriented ZnO nanorods, and then a chemical solution deposition method was employed to fabricate the BEuT matrix by coating the ZnO nanorods using a spin-coating technique. The nanocomposite thin films obtained exhibited significantly enhanced red photoluminescence (PL) properties. The PL enhancement can be attributed to very efficient radiation energy transfer from the ZnO nanorods to Eu³⁺ ions in the BEuT matrix due to two spectral overlaps between the emission spectra of the ZnO nanorods and the excitation bands of Eu³⁺ ions in the BEuT matrix: the spectral overlap between the sharp UV emission of ZnO centered at 380 nm and the excitation spectrum of the ⁷F₀ → ⁵L₆ transition of Eu³⁺ ions at 395 nm and that between the defect-related deep-level green emission band of ZnO centered at 525 nm and the excitation spectrum of the ⁷F₀ → ⁵D₂ transition of Eu³⁺ ions at 465 nm. Our study opens possibility of realizing highly efficient photoluminescent ferroelectric multifunctional integrated thin-film devices. In addition, the hybrid chemical solution method also provides a useful route for the synthesis of some new nanocomposite thin films consisting of other inorganic matrix and c-axis-oriented ZnO nanorods.