Red, Green, and Blue Luminescence from ZnGa₂O₄ Nanowire Arrays

Abstract

Large-area (>1 cm 2 ), vertically aligned ZnGa 2 O 4 , Mn 2þ -doped ZnGa 2 O 4 (ZnGa 2 O 4 :Mn 2þ ) and Cr 3þ -doped ZnGa 2 O 4 (ZnGa 2 O 4 :Cr 3þ ) nanowire arrays were synthesized by a two-step thermal evaporation method using ZnO nanowire arrays as the templates followed by reaction with Ga and/or dopant (Mn or Cr) vapors. Bright red, green, and blue luminescence was achieved, respectively, from ZnGa 2 O 4 :Cr 3þ , ZnGa 2 O 4 :Mn 2þ , and ZnGa 2 O 4 nanowire arrays under ultraviolet light irradiation. The realization of three primary colors from one host material suggests that full color display based on ZnGa 2 O 4 nanowires might be achievable.

Controlled Hydrothermal Synthesis and Photoluminescence of Nanocrystalline ZnGa2O4:Cr3+ Monospheres

“…Calcination at 800 °C greatly improves the excitation intensity, owing to the removal of water molecules, organic residues, and particularly the improved crystallinity of the phosphor powder. Exciting the phosphor with the O 2−  → Ga 3+ charge transfer band at 250 nm produced the 2 E →  4 A 2 emission of the Cr 3+ activators at ~700 nm [1], which further confirms the occurrence of Ga 3+  → Cr 3+ energy transfer. It is seen from the PL spectra that the phosphor calcined at 800 °C has an emission intensity ~6 times that of the as-synthesized one.…”

“…The compound has been drawing increasing attention for wide applications in the fields of lighting, display, and optical imaging for biology, owing to its excellent thermal and chemical stability and wide bandgap (~4.4–4.7 eV) [1]. ZnGa 2 O 4 is also known as a type of self-activated phosphors and may emit blue light under short UV or electron beam irradiation, owing to the occurrence of O-Ga charge transfer [1].…”

“…The compound has been drawing increasing attention for wide applications in the fields of lighting, display, and optical imaging for biology, owing to its excellent thermal and chemical stability and wide bandgap (~4.4–4.7 eV) [1]. ZnGa 2 O 4 is also known as a type of self-activated phosphors and may emit blue light under short UV or electron beam irradiation, owing to the occurrence of O-Ga charge transfer [1]. As a phosphor host, the Mn 2+ , Eu 3+ , and Cr 3+ activator ions doped into the ZnGa 2 O 4 lattice and residing at the Ga 3+ sites are known to emit bright green, red, and red luminescence under proper excitations, respectively [2].…”

Enhancement of photoluminescence, persistent luminescence and photocatalytic activity in ZnGa2O4 phosphors by lithium ion doping

“…Some researchers report that ZnGa 2 O 4 emits different emission colors when doped with appropriate activators, Cr 3+ -doped ZnGa 2 O 4 phosphor emits a red long-lasting luminescence at 696 nm and Mn 2+ -doped ZnGa 2 O 4 phosphor exhibits a green luminescence at 503 nm [7]. Undoped ZnGa 2 O 4 phosphor exhibits a blue luminescence at 430 nm when it is synthesized in an oxidizing ambient at high temperature [8], while it shows an ultraviolet emission band around 360 nm when it is synthesized in a reducing ambient [9].…”

Oxygen vacancy and dilute ferromagnetism of ZnGa2O4 doped with Co at the octahedral site

“…As well as being a blue emitting phosphor itself, it is a promising candidate as a matrix for doping transition metal and rare earth elements in multi-color electroluminescent devices because of its chemical, thermal and structural stability. [22][23][24][25] ZnGa 2 O 4 crystallizes in the cubic lattice with a spinel structure (space group Fd-3m), which possesses a couple of cation sites, namely the tetrahedral site surrounded by four oxygen anions and the octahedral site surrounded by six oxygens. A compound referred to as a normal spinel contains divalent cations on the tetrahedral site and trivalent ions in the octahedral site.…”