A review on the structural dependent optical properties and energy transfer of Mn4+ and multiple ion-codoped complex oxide phosphors

The tetravalent manganese Mn4+ ions with a 3d3 electron configuration as luminescence centers in solid-state inorganic compounds have been widely investigated because they emit bright light in the red to far-red region when they are excited by light with a wavelength in the UV to blue light region. Herein, we present an overview of the recent developments of Mn4+ and multiple ion such as Bi3+ and rare earth ion Dy3+, Nd3+, Yb3+, Er3+, Ho3+, and Tm3+ codoped complex oxide phosphors. Most of the specified host lattices of these complex oxide phosphors possess multiple metallic cations, which provide possible substitutions with different codopants and form various luminescence centers with diverse spectra. The luminescence of Mn4+ and multiple ion-codoped materials spans almost the whole visible light to near infrared (NIR) region. The crystal structures of complex oxide phosphors, the spectroscopic properties of Mn4+, and the energy transfer between Mn4+ and multiple ions are introduced and summarized in detail with regard to their practical applications. This review provides an insight into the optical properties of Mn4+ and the energy transfer process in multiple ion-codoped luminescence materials, which will be helpful in the development of novel excellent materials for applications in the lighting industry.

Realizing a novel dazzling far-red-emitting phosphor NaLaCaTeO6:Mn4+with high quantum yield and luminescence thermal stabilityviathe ionic couple substitution of Na++ La3+for 2Ca2+in Ca3TeO6:Mn4+for indoor plant cultivation LEDs

An ionic couple substitution strategy was initiated to explore the novel hosts for Mn⁴⁺luminescence in potential plant cultivation LED applications.

Effects of Impurity Doping on the Luminescence Performance of Mn4+-Doped Aluminates with the Magnetoplumbite-Type Structure for Plant Cultivation

Mn⁴⁺ activated LaMgAl₁₁O₁₉ (LMA/Mn⁴⁺) with red emitting phosphor was obtained by sintering under air conditioning. The X-ray diffraction pattern Rietveld refinement results reveal that three six-fold coordinated Al sites are substituted by Mn⁴⁺ ions. Furthermore, the chemical valence state of manganese in the LMA host was further confirmed through X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR). Photoluminescence emission (PL) and excitation (PLE) spectra of LMA/Mn⁴⁺ as well as the lifetime were measured, and the 663 nm emission is ascribed to the ²E_g→⁴A_2g from the 3d³ electrons in the [MnO₆]⁸⁻ octahedral complex. The emission spectrum matches well with the absorption of phytochrome. Temperature-dependent PL spectra show that the color changes of the phosphor at 420 K are 0.0110 for Δx and −0.0109 for Δy. Moreover, doping Zn²⁺ and Mg²⁺ ions in the host enhances the emission intensity of Mn⁴⁺ ions. These results highlight the potential of LMA/Mn⁴⁺ phosphor for a light-emitting diode (LED) plant lamp.

Improved luminescence and energy-transfer properties of Ca14Al10Zn6O35:Ti4+,Mn4+ deep-red-emitting phosphors with high brightness for light-emitting diode (LED) plant-growth lighting

Energy transfer from Ti⁴⁺ to Mn⁴⁺ was observed and verified in high brightness deep-red emission phosphors CAZO:Ti⁴⁺,Mn⁴⁺.

Preparation, characterization, and luminescence properties of double perovskite SrLaMgSbO6:Mn4+ far-red emitting phosphors for indoor plant growth lighting

Mn⁴⁺-activated SrLaMgSbO₆ far-red emitting phosphors with double perovskite structure were prepared by traditional solid-state reaction. The research on the crystal structure of the SrLaMgSbO₆:0.8%Mn⁴⁺ (SLMS:0.8%Mn⁴⁺) phosphors showed that the as-prepared sample was made up of two polyhedrons, [SbO₆] and [MgO₆]. Under the excitation of 333 nm, the SLMS:0.8%Mn⁴⁺ phosphors exhibited an intense far-red emission in the 625–800 nm wavelength range with CIE chromaticity coordinates of (0.733, 0.268), which could match well with the absorption spectrum of phytochrome P_FR. The optimal concentration of Mn⁴⁺ ions in the SLMS:Mn⁴⁺ phosphors was 0.8 mol%. Importantly, the as-prepared SLMS:0.8%Mn⁴⁺ phosphors had an internal quantum efficiency of 35%. The thermal stability of SLMS:0.8%Mn⁴⁺ phosphors was also investigated, and the activation energy was found to be 0.3 eV. Thus, the Mn⁴⁺-activated SLMS phosphors have great potential to serve as far-red emitting phosphors in indoor plant growth lighting.

Novel far-red emitting double perovskite SrLaMgSbO₆:Mn⁴⁺ phosphors were prepared and their photoluminescence properties were studied for applications in indoor plant growth lighting.

LaAlO₃:Mn4+ as Near-Infrared Emitting Persistent Luminescence Phosphor for Medical Imaging: A Charge Compensation Study

Mn4+-activated phosphors are emerging as a novel class of deep red/near-infrared emitting persistent luminescence materials for medical imaging as a promising alternative to Cr3+-doped nanomaterials. Currently, it remains a challenge to improve the afterglow and photoluminescence properties of these phosphors through a traditional high-temperature solid-state reaction method in air. Herein we propose a charge compensation strategy for enhancing the photoluminescence and afterglow performance of Mn4+-activated LaAlO₃ phosphors. LaAlO₃:Mn4+ (LAO:Mn4+) was synthesized by high-temperature solid-state reaction in air. The charge compensation strategies for LaAlO₃:Mn4+ phosphors were systematically discussed. Interestingly, Cl-/Na⁺/Ca2+/Sr2+/Ba2+/Ge4+ co-dopants were all found to be beneficial for enhancing LaAlO₃:Mn4+ luminescence and afterglow intensity. This strategy shows great promise and opens up new avenues for the exploration of more promising near-infrared emitting long persistent phosphors for medical imaging.

Highly efficient red emission and multiple energy transfer properties of Dy3+/Mn4+co-doped Ca14Zn6Ga10O35phosphors

Novel Dy³⁺/Mn⁴⁺co-doped Ca₁₄Zn₆Ga₁₀O₃₅phosphors have been synthesized by a solid state reaction technique.

A review on Mn4+ activators in solids for warm white light-emitting diodes

In this feature article, we will make a general survey on the recent progresses of Mn⁴⁺ doped red phosphors for warm white-light-emitting diodes.

Conversion of broadband UV-visible light to near infrared emission by Ca14Zn6Al10O35: Mn4+, Nd3+/Yb3+

Efficient Ca₁₄Zn₆Al₁₀O₃₅: Mn⁴⁺, Nd³⁺/Yb³⁺ spectral conversion materials have been prepared by a sol–gel method.