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A new red-emitting phosphor based on polyfluoride Na3Li3Sc2F12 doped with Mn4+ was prepared via a co-precipitation method at room temperature. Its crystal structure, luminescence properties and applications are discussed in detail. The as-synthesized phosphor emits red light with intense zero-phonon line (ZPL) at 618 nm under the excitation of 461 nm light. A higher energy of the 2Eg level of Mn4+ was observed in Na3Li3Sc2F12:Mn4+. The Racah parameters B and C were calculated to be 604 cm−1 and 3840 cm−1, respectively. The as-obtained Na3Li3Sc2F12:Mn4+ (4.86 mol%) shows a high internal quantum efficiency (IQE) of 66.8% and better resistance to thermal quenching. A white light-emitting diode (w-LED) with a high color rendering index of 92 and a low color temperature of 3694 K was fabricated. Hence, Na3Li3Sc2F12:Mn4+ as a new red-emitting phosphor has great potential application in w-LEDs. [ABSTRACT FROM AUTHOR]

In this work, a novel fluoroaluminate red phosphor of Cs2NaAl3F12:Mn4+ with excellent color purity was fabricated via the introduction of Mn4+ in the octahedral center. The crystal and electronic structures, luminescence properties and optical performances were characterized and investigated in detail. The evidences showed that Cs2NaAl3F12:Mn4+ well-crystallized into a single phase with particulate morphology, and the non-equivalent occupation in Cs2NaAl3F12 resulted in sharp red emissions with improved color purity upon blue light illumination. For solid-state lighting, the optical parameters consisted of the "blue-yellow-red" contributions significantly improved to a high color-rendering index of 88.7 and a low color temperature of 3856 K, indicating the potential use of Cs2NaAl3F12:Mn4+ for warm white light-emitting diode applications. [ABSTRACT FROM AUTHOR]

In this work, we present a novel single-phase red phosphor of Cs 2 NaAlF 6 :Mn4+ with two Al3+ lattice sites, which shows two groups of vibrational phonon sidebands and ultra-intense zero phonon line (ZPL) under blue light illumination. The evidences have shown that the interesting spectral features originate from the non-equivalent occupation of Mn4+ for both Al3+ sites, which induces the neighboring cation vacancies surrounding Mn4+ and highly distorted [MnF 6 octahedral in the Cs 2 NaAlF 6 host. The luminescent behavior of double sites occupied by Mn4+ can absorb researchers' interest on novel red-emitting phosphors. Profiting from the photoluminescence (PL) features, superior color rendering index of R a = 90.3, R 9 = 81, and low correlated color temperature of T c = 3967 K are achieved from white light-emitting diode (LED) by using yellow Y 3 Al 5 O 12 :Ce3+ (YAG) and red Cs 2 NaAlF 6 :Mn4+ phosphors as blue light converters. These results suggest that Cs 2 NaAlF 6 :Mn4+ for phosphor has a stupendous potential for LED lighting. A novel red phosphor of Cs 2 NaAlF 6 :Mn4+ with unprecedented spectral features of double vibrational phonon sidebands and ultra-intense ZPL comparable to the sharpest v 6 peak under blue light excitation was obtained. The amazing spectral feature is originated from the non-equivalent occupation of Mn4+ for both Al3+ sites in CNAF host. Profiting from the extraordinary PL properties, excellent optical performance of CNAF:Mn as color converter is achieved, implying its potential application in white LED lighting or display devices. Image 1 • A novel red-emitting phosphor of Cs 2 NaAlF 6 :Mn4+ has been successfully synthesized. • The crystal structure of Cs 2 NaAlF 6 :Mn4+ has been confirmed. • The spectral feature with ultra-intense zero phonon line has been elucidated. • Double sites occupancy of Mn4+ in Cs 2 NaAlF 6 has been verified. [ABSTRACT FROM AUTHOR]

A new red-emitting phosphor based on polyfluoride Na3Li3Sc2F12 doped with Mn4+ was prepared via a co-precipitation method at room temperature. Its crystal structure, luminescence properties and applications are discussed in detail. The as-synthesized phosphor emits red light with intense zero-phonon line (ZPL) at 618 nm under the excitation of 461 nm light. A higher energy of the 2Eg level of Mn4+ was observed in Na3Li3Sc2F12:Mn4+. The Racah parameters B and C were calculated to be 604 cm−1 and 3840 cm−1, respectively. The as-obtained Na3Li3Sc2F12:Mn4+ (4.86 mol%) shows a high internal quantum efficiency (IQE) of 66.8% and better resistance to thermal quenching. A white light-emitting diode (w-LED) with a high color rendering index of 92 and a low color temperature of 3694 K was fabricated. Hence, Na3Li3Sc2F12:Mn4+ as a new red-emitting phosphor has great potential application in w-LEDs. [ABSTRACT FROM AUTHOR]

To develop non-rare-earth or metal-free phosphors for white light-emitting diodes (WLEDs) are very significant and forward-looking. Here, a yellow-green-emitting g-C 3 N 4 derivative (p -Ph-g-C 3 N 4) consisting of 1,4-phenylene-inserted heptazine units was successfully prepared by 6,6'-(1,4-phenylene)bis(1,3,5-triazine-2,4-diamine) via thermal polymerization. Its emission is mainly located at 450–700 nm with the maximum wavelength (λ em,max) of 536 nm, its quantum yield (QY) is 15.7% (λ ex = 430 nm) which is much higher than that of bulk g-C 3 N 4 (ca. 5%). Under the excitation of 430 nm blue-emitting GaN-based chips (ca. 4.0 lm·W−1), p -Ph-g-C 3 N 4 together with non-rare-earth red-emitting K 2 SiF 6 :Mn4+ as phosphors, a series of cold, neutral, and warm WLEDs with good performances were fabricated. As for the best one, its color rendering index (CRI) is 84.3, correlate color temperature (CCT) is 5702 K, luminous efficiency (LE) is 5.40 lm·W−1, moreover, its CIE value (0.30, 0.34) is very close to (0.33, 0.33) of pure white light. The research results indicate p -Ph-g-C 3 N 4 can be used as an efficient metal-free quasi-green phosphor for WLEDs. White LEDs were fabricated by a yellow-green-emitting g-C 3 N 4 derivative and red-emitting K 2 SiF 6 :Mn4+ under the excitation of blue-emitting chips. [Display omitted] • A yellow-green-emitting metal-free g-C 3 N 4 derivative. • The derivative consisting of 1,4-phenylene-inserted heptazine units. • Cold/neutral/warm WLEDs all being fabricated. [ABSTRACT FROM AUTHOR]

Searching for efficient Mn4+ red phosphors for white lighting and display backlighting has drawn great attention. In this work, an efficient Mn4+-doped fluoroscandate, Rb 2 KScF 6 :Mn4+, with short fluorescence lifetime is prepared via a facile co-precipitation method. It was found that the nonequivalent occupation of Mn4+ for Sc3+ leads to the identifications of sharp red emissions, enhanced zero-phonon line, high quantum efficiency and short fluorescence lifetime upon blue light excitation. Thanks to the luminescent properties, good optical parameters of high color rendering index, low correlated color temperature, and acceptable color gamut were achieved by coating the red Rb 2 KScF 6 :Mn4+ phosphor with yellow Y 3 Al 5 O 12 :Ce3+ or green β -SiAlON:Eu2+ phosphor in various white light-emitting diodes, demonstrating its potential role for white light illumination and backlight display applications. • The crystal and electronic structures were analyzed for a novel Rb 2 KScF 6 :Mn4+ phosphor. • The luminescent properties including an enhanced zero-phonon line and a short fluorescence lifetime were confirmed. • The optical behavior of the Rb 2 KScF 6 :Mn4+ phosphor in multiple white light-emitting diodes was elucidated. [ABSTRACT FROM AUTHOR]

• NIR emitting A 2 KAlF 6 :Cr3+ phosphors were prepared by a co-precipitation method. • A 2 KAlF 6 :Cr3+ phosphors exhibit broad NIR emission with high quantum efficiencies. • The phosphors have excellent thermal stability of luminescence. • The full-spectrum WLEDs based on A 2 KAlF 6 :Cr3+have good photoelectric performances. Herein, NIR A 2 KAlF 6 :Cr3+ (A = Rb, Cs) phosphors prepared by a co-precipitation method exhibit broad excitation in the blue region and broad NIR emission with high quantum efficiencies (64% for Rb 2 KAlF 6 :0.025Cr3+, and 60% for Cs 2 KAlF 6 :0.02Cr3+). Furthermore, Rb 2 KAlF 6 :Cr3+ and Cs 2 KAlF 6 :Cr3+ phosphors maintain 95.3% and 90.2% of their room-temperature initial intensity at 150 °C, respectively. The full-spectrum white light-emitting diode (WLED) based on Rb 2 KAlF 6 :Cr3+ exhibits a high color-rendering index (94.8), a high luminous efficiency (99.5 lm/W), and a low correlation color temperature (3666 K). The results reveal that these phosphors can not only apply in full-spectrum illumination but also provide new in-depth insights into the design of NIR phosphors with high efficiency and thermal stability. Near-infrared A 2 KAlF 6 :Cr3+phosphors with high thermal stability and quantum efficiency were designed and prepared for fabricating high-performance full-spectrum white light-emitting diodes. [Display omitted] [ABSTRACT FROM AUTHOR]

A series of naphthyl-modified graphitic carbon nitride were prepared by using melamine, cyanuric acid as precursors and 6-(naphthalen-2-yl)-1,3,5-triazine-2,4-diamine as a molecular dopant. When their mass ratio was 20:20:1, the product (g–C 3 N 4 –Naphth 20:20:1) showed the best photoluminescence performances. The emission spectrum of g–C 3 N 4 –Naphth 20:20:1 was mainly at 410–650 nm and much wider than that of bulk g-C 3 N 4 (mainly at 410–550 nm), relative to bulk g-C 3 N 4 , the maximum emission wavelength (λ em,max) changed from 455 nm to 485 nm, the light color correspondingly changed from deep blue to blue-green, the PL efficiency increased from 5.1% to 11.3%. Excited by ultraviolet chips (λ em,max = 365 nm), a series of LEDs using g–C 3 N 4 –Naphth 20:20:1 blended in epoxy resin at 4.0 wt% together with red-emitting SrAlSiN 3 :Eu2+ at x wt-% (x = 0.08, 0.12, 0.16, and 0.20) as phosphors were fabricated. When x = 0.08, 0.12, 0.16, the LEDs emitted neutral white light, their correlate color temperatures (CCT) were 5277 K, 4602 K and 3794 K, color rendering indexes (CRI) were 85.4, 88.1 and 79.7, respectively. When x = 0.20, it was a warm white LED, its CCT was 3312 K and CRI was 83.3. The results suggested the naphthyl-modified g-C 3 N 4 can be used as efficient metal-free phosphors for LEDs. Blue-green-emitting naphthyl-modified graphitic carbon nitride (g–C 3 N 4 –Naphth) were prepared and used as phosphors in white LEDs. [Display omitted] • A series of naphthyl-modified g-C 3 N 4 were prepared. • The luminescent color changed from deep blue to blue-green after naphthyl modification. • The PL efficiency changed from 5.1% to 11.3% after naphthyl modification. • The naphthyl-modified g-C 3 N 4 was successfully used as phosphors in white LEDs. [ABSTRACT FROM AUTHOR]

A sp2-carbon-linked covalent organic framework (COF) containing tetraphenylethene units was successfully synthesized by using 2,2'-(1,4-phenylene)diacetonitrile and 4′,4‴,4‴'',4‴''''-(Ethene-1,1,2,2-tetrayl)tetrakis(([1,1′-biphenyl]-4-carbaldehyde)) as monomers. After being investigated by powder X-Ray diffraction (PXRD), nitrogen adsorption-desorption and theoretical calculations, the dual-pore eclipsed Kagome structure (AA-K) of the COF was confirmed. The COF emitted bright yellow light with a solid-state photoluminesce quantum yield (PLQY) of 39.2%. It exhibited high thermal stability with a thermal decomposition temperature (T d) of ca. 610 °C, and its relative emission intensity at 90 °C was nearly 80.0% of that at 30 °C. The COF was blended in epoxy resin at different concentrations and used as phosphors, excited by GaN-based blue-emitting chips (λ em,max ≈ 455 nm), a series of white light-emitting diodes (WLEDs) with different correlated color temperature (CCT) can be obtained. At 1.5 wt%, a cold WLED was obtained, its CCT was 6125 K, color rendering index (CRI) was 83.4, Commission Internationale de L'Eclairage (CIE) chromaticity coordinate was (0.32, 0.29), luminous efficiency (η L) was 20.31 lm·W−1. At 2.0 wt%, a neutral WLED was obtained, its CCT was 4293 K, CRI was 79.6, chromaticity coordinate was (0.36, 0.34) and η L was 19.71 lm·W−1. At 2.5 wt%, a warm WLED was obtained, its CCT was 3348 K, CRI was 69.4, chromaticity coordinate was (0.42, 0.42) and η L was 18.81 lm·W−1. The results suggested the COF can be used promising metal-free phosphors in WLEDs. [Display omitted] • A sp2-carbon-linked covalent organic framework (COF) containing tetraphenylethene units was synthesized. • The COF emitted bright yellow light with a solid-state photoluminesce quantum yield (PLQY) of 39.2%. • The thermal decomposition temperature (T d) of the COF was as high as 610 °C. • Cold/neutral/warm white LEDs with high performances were prepared by using the COF and blue-emitting chips. [ABSTRACT FROM AUTHOR]

• Cs 2 KCrF 6 :Mn4+ was designed and prepared at mild conditions. • Cs 2 KCrF 6 :Mn4+ exhibits high blue-light conversion efficiency. • Cs 2 KCrF 6 :Mn4+ has excellently thermal quenching property and color stability. • Cs 2 KCrF 6 :Mn4+ can improve the luminescent performances of w-LED. One red phosphor Cs 2 KCrF 6 :Mn4+ (CKCFM) with the cubic structure was prepared at mild conditions. Mn4+ in CKCFM with the highly symmetrical environment exhibit one broad excitation band peaking at 453 nm and narrow-band emission in the range from 600 to 650 nm. The optimized CKCFM has one highly external quantum yield of 46.7%. At the same time, the sample also has excellent thermal stability and color stability. The emission intensity of CKCFM at 160 °C is still higher than that at 20 °C. At last, one white light-emitting diode (w-LED) was obtained by combining CKCFM and Y 3 Al 5 O 12 :Ce3+with one blue LED chip. It shows excellent performance: color rendering index (Ra) up to 88.3, color temperature (CCT) down to 3986 K, showing that CKCFM can find application in w-LEDs. New red-emitting phosphor Cs 2 KCrF 6 :Mn4+ exhibits high blue-light conversion efficiency and a high thermal-quenching temperature for w-LEDs. [Display omitted] [ABSTRACT FROM AUTHOR]

A reddish-orange-emitting cationic iridium(III) complex [(dfppy) 2 Ir(EPTC)]PF 6 (dfppy: 2-(2,4-difluorophenyl)pyridine, EPTC: 9-ethyl-3-(3-(pyridin-2-yl)-1,2,4-triazin-5-yl)-9 H -carbazole) containing a carbazole-triazine bipolar unit was synthesized. The thermal decomposition temperature (T d) of the complex was 355 °C, its relative emission intensity at 100 °C was 78.6% of that at 20 °C, which was enough for it to be used in LEDs. Mainly due to the bipolar unit, [(dfppy) 2 Ir(EPTC)]PF 6 can efficiently absorb and be excited by blue light (λ em,max = 457 nm) of GaN chips. Excited by blue-emitting GaN chips, the complex can be used for fabricating reddish-orange LEDs, moreover, together with yellow-emitting Y 3 Al 5 O 12 :Ce3+ (YAG:Ce), neutral and warm white light-emitting diodes (WLEDs) can be obtained with good performances. When [(dfppy) 2 Ir(EPTC)]PF 6 was blended in silicone at 1.0, 1.5 and 2.0 wt% respectively, all together with YAG:Ce at 4.0 wt%, three efficient neutral WLEDs were obtained. Their correlate color temperatures (CCT) were 4874 K, 4312 K and 3665 K, color rendering indexes (CRI) were 80.2, 78.3 and 76.4, luminous efficiencies (η L) were 88.5 lm·W−1, 83.6 lm·W−1 and 67.4 lm·W−1, Commission International de I'Eclairage (CIE) values were (0.34, 0.32), (0.36, 0.33) and (0.38, 0.33) respectively. When blending concentration of [(dfppy) 2 Ir(EPTC)]PF 6 was increased to 2.5 wt% together with YAG:Ce still at 4.0 wt%, a warm WLED was obtained, its CCT was 3282, CRI was 73.9, η L was 63.0 lm·W−1, and CIE value was (0.40, 0.35). Image 1 • A reddish-orange-emitting cationic iridium(III) complex containing a carbazole-triazine bipolar unit.. • The complex can be efficiently excited by blue-emitting GaN chips mainly due to the effect of the bipolar unit. • Together with Y 3 Al 5 O 12 :Ce3+ as phosphors, neutral and warm white light-emitting diodes can be obtained with good performances. [ABSTRACT FROM AUTHOR]