Controlled Mixed Violet–Blue–Red Electroluminescence from Eu:Nano-Phosphors/ZnO-Nanowires/p-GaN Light-Emitting Diodes

Abstract

Europium (Eu):Y 2 O 3 -nanoparticles/Mg:ZnO-nanowires/p-GaN and (Eu):chelate-based light-emitting diode (LED) structures have been fabricated, showing controlled mixed near-UV, violet, and red electroluminescence from trivalent europium. The magnesium (Mg)-doped ZnO (Mg:ZnO)-nanowires/p-GaN heterojunction were integrated into the LED structure and were covered on the top with the nanoparticle of yttrium oxide doped with trivalent europium ions (Eu 3+ :Y 2 O 3 ) or by Eu:chelate. Samples exhibit mixed UV/blue light at ∼384 nm coming from the Mg:ZnO structure and a sharp red emission at ∼611 nm related to the intra4f transition of Eu ions. It is found that with Mg doping of ZnO, the emission wavelength of LEDs in the near-ultraviolet region is shifted to a smaller wavelength, thus being better adapted to the trivalent europium excitation band. Radiative energy transfer is achieved through the strong overlap between the emission wavelength from n-(Mg:ZnO)/p-GaN heterojunction and 7 F 0 -5 L 6 absorption of Eu 3+ ions in the case of Eu:Y 2 O 3 or of the (Eu):chelate intensive absorption bands. Indeed, the (Eu):chelate/(Mg:ZnO)-nanowires/p-GaN structure appears to be more adapted to UV/blue and red dual emission than Eu:Y 2 O 3 , for which low absorption prevents efficient emission. Our results demonstrate that the designs of nano-LED structures and of the chelate ligands are crucial to enhance the performance of electroluminescence devices based on ZnO nanowire arrays and rare-earth metal complexes.

Enhancement in red emission at room temperature from europium doped ZnO nanowires by 1,10 phenanthroline-europium interface induced resonant excitations

“…However, it has also been considered for the development of multiple color light emitting diodes from UV-to-red or even as a white light source. 3,6,7 Light emission from ZnO using the crystal field (CF) levels of rare-earth (RE) ions is an interesting prospect of application. Trivalent rare earth ions in the suitable matrix allow us to achieve intra-4f transition related sharp emissions due to the weakening of spin-forbidden transition caused by crystal field of the host matrix.…”

Pt/Y2O3:Eu3+ composite nanotubes: Enhanced photoluminescence and application in dye-sensitized solar cells

“…Among these materials, Y 2 O 3 offers good chemical and photochemical stability, a high melting point, and, most importantly, can be easily doped. Y 2 O 3 doped with trivalent europium ions (Y 2 O 3 :Eu 3+ ) is a well-known red-emitting phosphor used in cathode ray tubes, fluorescent lamps, and projection television tubes [16]. For luminescent materials, Y 2 O 3 :Eu 3+ not only exhibits a sharp emission bandwidth, high photostability, and long lifetime but can also combine with some compounds [17] such as Y 2 O 3 :Yb, Er@mSiO 2 -Cu x S for enhanced chemophotothermal anti-cancer therapy and dual-modal imaging [18].…”

Synthesis, structural characterization and luminescent properties of a novel europium ternary complex Eu(2-A-4-CBA)3phen

“…For more than a decade, lanthanide-based coordination complexes have attracted a growing attention because of they possess remarkable structural diversities and exhibit attractive photophysical properties (large Stokes shift, long fluorescence lifetime, high luminescence quantum yield, narrow bandwidth) and have a wealth of applications in disparate fields, such as phosphors [1], clinical medicine [2], biology [3], catalysis [4], material science [5], and optoelectronic device [6,7].…”