Synthesis and narrow red luminescence of Cs2HfF6:Mn4+, a new phosphor for warm white LEDs

Senden, Tim; Harten, Elleke J van; Meijerink, Andries

doi:10.1016/j.jlumin.2017.10.006

Cited by 78 publications

(53 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This agrees with the ZPL energy position found in Ref. . With this assignment, all other peaks in the emission spectra match very well with the nearly symmetrical Stokes and anti‐Stokes lines induced by interaction with octahedral normal modes, whose energies are typical for the fluoride materials (Table ).…”

Section: Crystal Field Calculations Of the Mn4+ Energy Levels In Rb2hsupporting

confidence: 90%

“…We should point out that in Ref. [4], the values of the determined Racah parameters are B = 601 cm À1 and C = 3825 cm À1 .…”

Section: Calculations Of the Mn 4 + Energy Levels In Rb 2 Hff 6 And Cmentioning

confidence: 81%

“…Research aimed at developing new Mn 4+ ‐based phosphors for LED devices is receiving considerable attention due to the commercialization of the K 2 SiF 6 :Mn 4+ phosphor. Recently, 2 novel red‐emitting phosphors A 2 HfF 6 :Mn 4+ ( A =Rb, Cs) with emission in the required 590–650 nm wavelength range have been reported. Details of the synthesis, optical properties including first‐principles calculations pertaining to the band structure of the Rb 2 HfF 6 host were described .…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

First‐principles and crystal‐field calculations of the electronic and optical properties of two novel red phosphors Rb₂HfF₆:Mn⁴⁺ and Cs₂HfF₆:Mn⁴⁺

Liu

et al. 2018

J Am Ceram Soc

View full text Add to dashboard Cite

The electronic, structural, and optical properties of 2 red phosphors, Rb2HfF6:Mn4+ and Cs2HfF6:Mn4+, are evaluated using the first‐principles and crystal field theory methods. The calculated trigonal splitting of the Mn4+ orbital triplets perfectly matches the experimental excitation spectra. The structural and electronic properties of the mixed compound RbCsHfF6 are also studied theoretically. In the mixed compound, the inversion center symmetry around the Hf site is removed. This symmetry lowering may result in an increase in the Mn4+ 2E→4A2 zero phonon line (ZPL) intensity, which is very weak in the 2 end members. This finding may be of interest for increasing the phosphor luminosity. It is believed that such a mechanism of local site symmetry lowering by preparing solid solutions may be used for other systems as well, to gain ZPL intensity and perhaps to minimize thermal losses, eventually leading to improved phosphor materials.

show abstract

Section: Crystal Field Calculations Of the Mn4+ Energy Levels In Rb2hsupporting

confidence: 90%

“…We should point out that in Ref. [4], the values of the determined Racah parameters are B = 601 cm À1 and C = 3825 cm À1 .…”

Section: Calculations Of the Mn 4 + Energy Levels In Rb 2 Hff 6 And Cmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

First‐principles and crystal‐field calculations of the electronic and optical properties of two novel red phosphors Rb₂HfF₆:Mn⁴⁺ and Cs₂HfF₆:Mn⁴⁺

Liu

et al. 2018

J Am Ceram Soc

View full text Add to dashboard Cite

show abstract

“…Like the 2 E → 4 A 2 transition, the 4 A 2 → 4 T 2 transition is electric dipole (parity) forbidden and gains intensity by coupling with vibrations (for more details on the vibronic structure of the 4 A 2 → 4 T 2 excitation band, see refs. 15,16,44 ). As a result, the PL intensity I PL will scale with temperature as 20,41,45 :with I (0) being the PL intensity at T = 0 K. The results in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The energy of the Mn 4+ 4 T 2 state depends on the crystal field splitting Δ O (Fig. 2b), where Δ O is typically larger for shorter Mn–F distances 44,58 . For Mn 4+ -doped fluorides the luminescence quenching temperature can therefore be raised by selecting host lattices with short M 4+ –F − distances (see Supplementary Figure S10a).…”

Section: Resultsmentioning

confidence: 99%

Quenching of the red Mn4+ luminescence in Mn4+-doped fluoride LED phosphors

2018

Self Cite

View full text Add to dashboard Cite

Red-emitting Mn4+-doped fluorides are a promising class of materials to improve the color rendering and luminous efficacy of white light-emitting diodes (w-LEDs). For w-LEDs, the luminescence quenching temperature is very important, but surprisingly no systematic research has been conducted to understand the mechanism for thermal quenching in Mn4+-doped fluorides. Furthermore, concentration quenching of the Mn4+ luminescence can be an issue but detailed investigations are lacking. In this work, we study thermal quenching and concentration quenching in Mn4+-doped fluorides by measuring luminescence spectra and decay curves of K2TiF6:Mn4+ between 4 and 600 K and for Mn4+ concentrations from 0.01% to 15.7%. Temperature-dependent measurements on K2TiF6:Mn4+ and other Mn4+-doped phosphors show that quenching occurs through thermally activated crossover between the 4T2 excited state and 4A2 ground state. The quenching temperature can be optimized by designing host lattices in which Mn4+ has a high 4T2 state energy. Concentration-dependent studies reveal that concentration quenching effects are limited in K2TiF6:Mn4+ up to 5% Mn4+. This is important, as high Mn4+ concentrations are required for sufficient absorption of blue LED light in the parity-forbidden Mn4+ d–d transitions. At even higher Mn4+ concentrations (>10%), the quantum efficiency decreases, mostly due to direct energy transfer to quenching sites (defects and impurity ions). Optimization of the synthesis to reduce quenchers is crucial for developing more efficient highly absorbing Mn4+ phosphors. The present systematic study provides detailed insights into temperature and concentration quenching of Mn4+ emission and can be used to realize superior narrow-band red Mn4+ phosphors for w-LEDs.

show abstract

Luminescence from Self‐Trapped Excitons and Energy Transfers in Vacancy‐Ordered Hexagonal Halide Perovskite Cs₂HfF₆ Doped with Rare Earths for Radiation Detection

Adhikari

Shrivastava

McClain

et al. 2022

Advanced Optical Materials

View full text Add to dashboard Cite

Perovskite materials possess diversified structures, with a virtue of customizable chemical compositions to generate versatile chemical, mechanical, and physical properties. Traditional lead halide perovskites with the general formula APbX 3 , where A is an organic (CH 3 NH 3 + , CH(NH 2 ) 2 + ) or inorganic cation (Cs + ), and X is a halide (I − , Br − , or Cl − ), [1] have received much research as solar cells and optical materials. [2][3][4] However, the facts of toxicity and low stability of these materials have urged researchers to quest for other perovskite systems.Cs 2 HfCl 6 (CHC) is a type of Pb-free material with a vacancy-ordered double perovskite structure, with a space group of 3 Fm m (No. 225). [5] Compared with other double perovskites such as Cs 2 AgBiX 6 (X = Cl, Br) without vacancy, [6][7][8] the CHC in a 2:1:6 atomic ratio contains unoccupied B′ sites when expressed as A 2 BB′X 6 , with a low mass density of 3.56 g cm -3 . [9] This type of material with a vacancy-ordered double perovskite structure has received increasingly renewed attention in the past years. [10][11][12][13] Burger et al. have grown CHC single crystals, which were nonhygroscopic but could give high light yield by γ-rays without any intentional doping. [14] The scintillation was centered at 400 nm, with a principal decay time of 4.37 µs. Through first-principles calculations, Kang and Biswas found that although its bandgap is large (6.34 eV), the luminescence is originated from self-trapped excitons (STEs) that are caused by (HfCl 6 ) 2octahedra trapping localized carries. [15] Further, using undoped CHC single crystals, Král et al. identified photoluminescence (PL) emission bands at 380 nm by STEs, and 460 nm by defects. [16] The emissions could be tuned through dopants. [17][18][19] The CHC material has been widely studied as scintillators [14,[20][21][22][23][24][25][26][27] and light-emitting diodes (LEDs) applications. [17] Besides, other halides in this family, Cs 2 HfBr 6 (CHB) [28] and Cs 2 HfI 6 (CHI), [29,30] have also been reported as scintillators.However, the research on Cs 2 HfF 6 (CHF), the first member of the halide Cs 2 HfX 6 family, is much limited compared to other members. Unlike CHC, CHB, and CHI with a double perovskite structure, CHF crystalized as a hexagonal Bravais Compared to halides Cs 2 HfX 6 (X = Cl, Br, I) with a vacancy-ordered cubic double perovskite structure, the halide Cs 2 HfF 6 (CHF), with a hexagonal Bravais lattice, possesses a higher mass density and chemical stability for radiation detection. Luminescence properties and energy transfer mechanisms of rare-earths-doped CHF materials are studied here. The structure of CHF is identified as a new type of vacancy-ordered hexagonal perovskite, with the same type of building blocks of the double perovskite but stacked with single layers. Density-functional theory calculations reveal a large bandgap of CHF. A broad emission is observed from the pristine CHF host, which is suggested to be associated with self-trapped excitons (STEs). A series of...

show abstract

Synthesis and narrow red luminescence of Cs2HfF6:Mn4+, a new phosphor for warm white LEDs

Cited by 78 publications

References 52 publications

First‐principles and crystal‐field calculations of the electronic and optical properties of two novel red phosphors Rb₂HfF₆:Mn⁴⁺ and Cs₂HfF₆:Mn⁴⁺

First‐principles and crystal‐field calculations of the electronic and optical properties of two novel red phosphors Rb₂HfF₆:Mn⁴⁺ and Cs₂HfF₆:Mn⁴⁺

Quenching of the red Mn4+ luminescence in Mn4+-doped fluoride LED phosphors

Luminescence from Self‐Trapped Excitons and Energy Transfers in Vacancy‐Ordered Hexagonal Halide Perovskite Cs₂HfF₆ Doped with Rare Earths for Radiation Detection

Contact Info

Product

Resources

About

Synthesis and narrow red luminescence of Cs2HfF6:Mn4+, a new phosphor for warm white LEDs

Cited by 78 publications

References 52 publications

First‐principles and crystal‐field calculations of the electronic and optical properties of two novel red phosphors Rb2HfF6:Mn4+ and Cs2HfF6:Mn4+

First‐principles and crystal‐field calculations of the electronic and optical properties of two novel red phosphors Rb2HfF6:Mn4+ and Cs2HfF6:Mn4+

Quenching of the red Mn4+ luminescence in Mn4+-doped fluoride LED phosphors

Luminescence from Self‐Trapped Excitons and Energy Transfers in Vacancy‐Ordered Hexagonal Halide Perovskite Cs2HfF6 Doped with Rare Earths for Radiation Detection

Contact Info

Product

Resources

About

First‐principles and crystal‐field calculations of the electronic and optical properties of two novel red phosphors Rb₂HfF₆:Mn⁴⁺ and Cs₂HfF₆:Mn⁴⁺

First‐principles and crystal‐field calculations of the electronic and optical properties of two novel red phosphors Rb₂HfF₆:Mn⁴⁺ and Cs₂HfF₆:Mn⁴⁺

Luminescence from Self‐Trapped Excitons and Energy Transfers in Vacancy‐Ordered Hexagonal Halide Perovskite Cs₂HfF₆ Doped with Rare Earths for Radiation Detection