Luminescence of delafossite-type CuAlO₂ fibers with Eu substitution for Al cations

CuAlO₂ has been examined as a potential luminescent material by substituting Eu for Al cations in the delafossite structure. CuAlO₂:Eu³⁺ nanofibers have been prepared via electrospinning for the ease of mitigating synthesis requirements and for future optoelectronics and emerging applications. Single-phase CuAlO₂ fibers could be obtained at a temperature of 1100 °C in air. The Eu was successfully doped in the delafossite structure and two strong emission bands at ~405 and 610 nm were observed in the photoluminescence spectra. These bands are due to the intrinsic near-band-edge transition of CuAlO₂ and the f-f transition of the Eu³⁺ activator, respectively. Further electrical characterization indicated that these fibers exhibit semiconducting behavior and the introduction of Eu could act as band-edge modifiers, thus changing the thermal activation energies. In light of this study, CuAlO₂:Eu³⁺ fibers with both strong photoluminescence and p-type conductivity could be produced by tailoring the rare earth doping concentrations.