Phosphors by Design: Approaches Toward the Development of Advanced Luminescent Materials

Hermus, Martin; Brgoch, Jakoah

doi:10.1149/2.f06154if

Cited by 6 publications

(4 citation statements)

References 65 publications

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“…In the search for new phosphors, research has shown one viable method for identifying materials with a high Φ is to find structurally rigid host compounds with high atomic connectivity 16 . These characteristics enhance Φ by inhibiting soft phonon modes that lead to non-radiative relaxation, thereby increasing the propensity for photon emission.…”

Section: Introductionmentioning

confidence: 99%

Identifying an efficient, thermally robust inorganic phosphor host via machine learning

Zhuo¹,

Tehrani²,

Oliynyk³

et al. 2018

Nat Commun

274

178

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Rare-earth substituted inorganic phosphors are critical for solid state lighting. New phosphors are traditionally identified through chemical intuition or trial and error synthesis, inhibiting the discovery of potential high-performance materials. Here, we merge a support vector machine regression model to predict a phosphor host crystal structure’s Debye temperature, which is a proxy for photoluminescent quantum yield, with high-throughput density functional theory calculations to evaluate the band gap. This platform allows the identification of phosphors that may have otherwise been overlooked. Among the compounds with the highest Debye temperature and largest band gap, NaBaB9O15 shows outstanding potential. Following its synthesis and structural characterization, the structural rigidity is confirmed to stem from a unique corner sharing [B3O7]5– polyanionic backbone. Substituting this material with Eu2+ yields UV excitation bands and a narrow violet emission at 416 nm with a full-width at half-maximum of 34.5 nm. More importantly, NaBaB9O15:Eu2+ possesses a quantum yield of 95% and excellent thermal stability.

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Section: Introductionmentioning

confidence: 99%

Identifying an efficient, thermally robust inorganic phosphor host via machine learning

Zhuo¹,

Tehrani²,

Oliynyk³

et al. 2018

Nat Commun

274

178

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show abstract

“…Designing an effective phosphor exhibiting bright luminescence requires careful consideration of the crystal structure to tune interactions between luminescent centers and the host lattice as well as to suppress nonradiative recombination pathways. , A particularly useful host crystal structure that exhibits a low-phonon cutoff energy and limits cross-relaxation mechanisms is the tetragonal matlockite PbFCl structure (space group P 4/ nmm) . − In this article, we examine LaOCl, which adopts the PbFCl structure (as depicted in the inset of Figure S1), as a host lattice for multiple luminescent centers. In this structure, infinite sheets of (LaO) n n + and Cl – ions are alternated along the crystallographic c direction. − The trivalent lanthanum cations have a local coordination environment described by C 4 v symmetry wherein each La-ion resides in a monocapped square antiprism defined by four oxygen atoms in an underlying plane (with a La–O bond distance of 2.39 Å) and five chloride ions in the layers above.…”

Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

In a Different Light: Deciphering Optical and X-ray Sensitization Mechanisms in an Expanded Palette of LaOCl Phosphors

et al. 2018

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The conversion and numerical amplification of X-ray photons to visible light is at the heart of numerous technological applications spanning the range from X-ray detectors and scintillators to radiographic medical imaging devices. The need for increased sensitivity and spatial resolution to reduce radiation exposure and provide better differentiation of specimens presenting an X-ray contrast has been a strong driving force in the search for novel X-ray phosphors. However, the current palette of X-ray phosphors is rather sparse. The development of color tunable phosphors necessitates the incorporation of multiple dopants, which in turn interact through complex sensitization mechanisms that are poorly understood for high-energy excitation. In this work, we describe the stabilization of multiply alloyed LaOCl nanocrystals incorporating Tb3+ cations in conjunction with either divalent or trivalent europium ions, yielding phosphors emitting in the blue–green and green–red regions of the electromagnetic spectrum, respectively. The choice of the coordinating ligand (tri-n-octylphosphine oxide versus oleylamine) dictates the oxidation state of the incorporated Eu-ions. Pronounced differences are observed in sensitization mechanisms upon optical and X-ray excitation thereby considerably modifying the perceived color of the X-ray phosphors as compared to stimulation by ultraviolet illumination. Upon UV illumination, strong Tb3+ → Eu3+ sensitization is observed for LaOCl nanocrystals incorporating trivalent europium ions; however, upon X-ray excitation, this sensitization pathway is instead supplanted by independent La3+ → Eu3+ and La3+ → Tb3+ sensitization routes. In contrast, strong Eu2+ → Tb3+ sensitization is observed for LaOCl nanocrystals incorporating divalent europium ions upon both optical and X-ray excitation (La3+ → Eu2+ → Tb3+ and La3+ → Tb3+ pathways are also observed in X-ray excited optical luminescence spectra). The increased efficacy of the Eu2+ → Tb3+ as compared with Tb3+→ Eu3+ sensitization pathway derives from the parity allowed nature and orders of magnitude higher absorption cross-section for the excitation of the divalent Eu-ion. A strong suppression of luminescence intensity is observed upon excitation at the giant resonance absorption for all of the observed emission bands and corresponds to a change in mechanism from the creation of multiple thermal electron–hole pairs to a nonradiative Coster–Kronig process dominated by Auger photoionization.

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“…In contrast, the structural rigidity of a phosphor is closely related to its thermal stability and a higher structural rigidity can effectively suppress the nonradiative transitions, which in turn gives rise to a phosphor with high efficiency. However, it is often difficult to identify compounds that are more structurally rigid than others [40] . A more tractable method for determining structural rigidity is to evaluate the Debye temperature of the material [41] .…”

Section: Materials Properties Predictionmentioning

confidence: 99%

A mini review of machine learning in inorganic phosphors

Jiang¹,

Xue²,

Lv³

et al. 2022

J Mater Inf

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Machine learning has promoted the rapid development of materials science. In this review, we provide an overview of recent advances in machine learning for inorganic phosphors. We take two aspects of material properties prediction and optimization based on iterative experiments as entry points to outline the applications of machine learning for inorganic phosphors in terms of Debye temperature prediction and luminescence intensity and thermal stability optimization. By analyzing the machine learning methods and their application objectives, current problems are summarized and suggestions for subsequent development are proposed.

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Phosphors by Design: Approaches Toward the Development of Advanced Luminescent Materials

Cited by 6 publications

References 65 publications

Identifying an efficient, thermally robust inorganic phosphor host via machine learning

Identifying an efficient, thermally robust inorganic phosphor host via machine learning

In a Different Light: Deciphering Optical and X-ray Sensitization Mechanisms in an Expanded Palette of LaOCl Phosphors

A mini review of machine learning in inorganic phosphors

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