White-Light Emitting Di-Ureasil Hybrids

White-light emitting materials have emerged as important components for solid state lighting devices with high potential for the replacement of conventional light sources. Herein, amine-functionalized organic-inorganic di-ureasil hybrids consisting of a siliceous skeleton and oligopolyether chains codoped with lanthanide-based complexes, with Eu3+ and Tb3+ ions and 4,4′-oxybis(benzoic acid) and 1,10-phenanthroline ligands, and the coumarin 1 dye were synthesized by in situ sol–gel method. The resulting luminescent di-ureasils show red, green, and blue colors originated from the Eu3+, Tb3+, and C1 emissions, respectively. The emission colors can be modulated either by variation of the relative concentration between the emitting centers or by changing the excitation wavelength. White light emission is achieved under UV excitation with absolute quantum yields of 0.148 ± 0.015, 0.167 ± 0.017, and 0.202 ± 0.020 at 350, 332, and 305 nm excitation, respectively. The emission mechanism was investigated by photoluminescence and UV–visible absorption spectroscopy, revealing an efficient energy transfer from the organic ligands to the Ln3+ ions and the organic dye, whereas negligible interaction between the dopants is discerned. The obtained luminescent di-ureasils have potential for optoelectronic applications, such as in white-light emitting diodes.

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Sr2−xBaxTiO4:Eu3+, Gd3+: A Novel Blue Converting Yellow-Emitting Phosphor for White Light-Emitting Diodes

Journal of Nanomaterials ◽

10.1155/2015/103689 ◽

2015 ◽

Vol 2015 ◽

pp. 1-5

Author(s):

Limin Dong ◽

Jiatong Zhao ◽

Qin Li ◽

Zhidong Han

Keyword(s):

Blue Light ◽

White Light ◽

Single Phase ◽

Light Emission ◽

Light Emitting Diode ◽

Sol Gel ◽

Excitation Wavelength ◽

Light Emitting ◽

Gel Method ◽

White Light Emitting Diodes

A highly intense yellow-emitting phosphorSr2-xBaxTiO4:Eu3+,Gd3+peaking at 593–611 nm was synthesized by the sol-gel method. XRD and SEM show that the samples are single phase and have irregular shape. The excitation wavelength matches well with that of the emission of the blue-light-emitting diode. The emission peaks at 593 and 611 nm are attributed to the transitions from the5D0-7F1and5D0-7F2ofEu3+ions, respectively.Gd3+was used as sensitizer, aiming at increasing the luminous intensity. A certain amount ofSr2+andBa2+is contributed to the intensity of light emission.

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Tunable luminescence and white light emission of mixed lanthanide–organic frameworks based on polycarboxylate ligands

Journal of Materials Chemistry C ◽

10.1039/c5tc04432d ◽

2016 ◽

Vol 4 (16) ◽

pp. 3364-3374 ◽

Cited By ~ 86

Author(s):

Jiawei Wu ◽

Huabin Zhang ◽

Shaowu Du

Keyword(s):

White Light ◽

Light Emission ◽

Relative Concentration ◽

White Light Emission ◽

Excitation Wavelength

This review highlights the luminescence tuning and white light emission of aromatic polycarboxylate-based mixed Ln-MOFs by changing the relative concentration of the constituent Ln3+ ions or the excitation wavelength.

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A color tunable and white light emitting Ca2Si5N8:Ce3+,Eu2+ phosphor via efficient energy transfer for near-UV white LEDs

Dalton Transactions ◽

10.1039/c8dt01430b ◽

2018 ◽

Vol 47 (19) ◽

pp. 6860-6867 ◽

Cited By ~ 23

Author(s):

Chao Li ◽

Hongwei Zheng ◽

Hengwei Wei ◽

Shijie Qiu ◽

Ling Xu ◽

...

Keyword(s):

Energy Transfer ◽

White Light ◽

Single Phase ◽

Light Emission ◽

Efficient Energy Transfer ◽

Light Emitting ◽

White Leds ◽

Efficient Energy ◽

Challenging Issue ◽

Color Tunable

Achieving tunable color and white light emission in a single phase phosphor is a challenging issue.

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Synthesis of graphene oxide dots for excitation-wavelength independent photoluminescence at high quantum yields

Journal of Materials Chemistry C ◽

10.1039/c5tc00492f ◽

2015 ◽

Vol 3 (17) ◽

pp. 4553-4562 ◽

Cited By ~ 28

Author(s):

Chiao-Yi Teng ◽

Te-Fu Yeh ◽

Kuang-I Lin ◽

Shean-Jen Chen ◽

Masahiro Yoshimura ◽

...

Keyword(s):

Graphene Oxide ◽

Quantum Yield ◽

White Light ◽

Light Emission ◽

Quantum Yields ◽

Excitation Wavelength ◽

Nitrogen Doped ◽

Violet Light ◽

Nitrogen Doped Graphene ◽

Doped Graphene

Nitrogen-doped graphene oxide dots exhibit excitation-wavelength independent photoluminescence at 530 nm and 50% quantum yield. The dots show excellent white light emission by combining green emissions with violet light used for excitation.

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Warm-white luminescence of Dy3+ and Sm3+ co-doped NaSrPO4 phosphors through energy transfer between Dy3+ and Sm3+ ions

10.21203/rs.3.rs-217689/v1 ◽

2021 ◽

Author(s):

Wen Yan ◽

Junhan Li ◽

Wentao Zhang ◽

Xi Gao ◽

Peicong Zhang

Keyword(s):

Energy Transfer ◽

White Light ◽

Sol Gel ◽

Synthesis Temperature ◽

Dipole Transition ◽

Efficient Energy Transfer ◽

Light Emitting ◽

Co Doping ◽

Warm White Light ◽

Co Doped

Abstract Series of white-light-emitting NaSrPO4:Dy3+ phosphors were synthesized via a sol-gel method. Small amounts of Sm3+ ions were co-doped into the phosphors to enhance their luminescence. The effects of Dy3+/Sm3+ co-doping concentrations and synthesis temperature on the phosphors’ structures and luminescence properties were investigated. The results of X-ray diffraction confirmed that the characteristic diffraction peaks of the phosphors were in accord with those of the standard NaSrPO4 structure. Energy dispersive spectroscopy indicated that the NaSrPO4:Dy3+ samples were prepared with stoichiometric ratios of elements. Under ultraviolet light excitation of 348 nm, the NaSrPO4:Dy3+ phosphors emitted a white light which was composed of two emission peaks at 484 nm (blue) and 577 nm (yellow) corresponding to the magnetic dipole transition 4F9/2 → 6H15/2 and electronic dipole transition 4F9/2 → 6H13/2 of Dy3+ ions, respectively. Based on Sm3+ co-doping, a characteristic red emission at 602 nm arose and a warm-white light containing a lower CCT value was obtained. Besides, the luminescence lifetime of Dy3+ decreased while that of Sm3+ increased as dosages of Sm3+ were added, indicating efficient energy transfer from Dy3+ to Sm3+ happened. Therefore, NaSrPO4:Dy3+, Sm3+ phosphors are promising candidates for application in warm-white light-emitting diodes.

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New White Light-Emitting Halochromic Stilbenes with Remarkable Quantum Yields and Aggregation-Induced Emission

10.21203/rs.3.rs-1053023/v1 ◽

2021 ◽

Author(s):

Farhad Panahi ◽

Ali Mahmoodi ◽

Sajjad Ghodrati ◽

Ali Ashtiani ◽

Fazlolah Eshghi

Keyword(s):

White Light ◽

High Performance ◽

Density Functional ◽

Light Emission ◽

Visible Region ◽

Emission Spectra ◽

Cost Effective ◽

Quantum Yields ◽

Light Quantum ◽

Light Emitting

Abstract Highly efficient single-component white light emitters (SWLEs), are attractive candidates for the simple and cost-effective fabrication of high-performance lighting devices. This study introduced a donor–π–acceptor and a donor–π–donor stilbene-based chromophores, representing pH-responsive fluorescence. The emitters showed yellow and green fluorescence in their neutral form. At the same time, protonation of the chromophores caused blue fluorescence color with a strong hypsochromic shift. The white light emission (WLE) for these chromophores was observed at approximately pH=3 due to the simultaneous presence of the neutral and protonated forms of the chromophores, covering almost all the emission spectra in the visible region (400-700 nm). These chromophores presented exceptional white light quantum yields (Φ) between 31-54%, which was desirable for producing white light-emitting devices. Density functional theory (DFT) and time-dependent (TD)-DFT were applied to study the structural and electronic properties of the chromophores.

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Quantum Dot–Polyfluorene Composites for White-Light-Emitting Quantum Dot-Based LEDs

Nanomaterials ◽

10.3390/nano10122487 ◽

2020 ◽

Vol 10 (12) ◽

pp. 2487

Author(s):

Mariya Zvaigzne ◽

Irina Domanina ◽

Dmitriy Il’gach ◽

Alexander Yakimansky ◽

Igor Nabiev ◽

...

Keyword(s):

Quantum Dot ◽

Emission Spectrum ◽

Polymer Matrix ◽

White Light ◽

Light Emission ◽

Structural Instability ◽

Organic Ligands ◽

Light Sources ◽

Light Emitting ◽

Chemical Structures

Colloidal quantum dots (QDs) are a promising luminescent material for the development of next generation hybrid light-emitting diodes (QDLEDs). In particular, QDs are of great interest in terms of the development of solid-state light sources with an emission spectrum that mimics daylight. In this study, we used CdSe(core)/ZnS/CdS/ZnS(shell) QDs with organic ligands mimicking polyfluorene and its modified derivatives to obtain QD–polymer composites emitting white light. We found that the emission of the composites obtained by spin-coating, being strongly dependent on the chemical structure of the polymer matrix and the QD-to-polymer mass ratio, can be accurately controlled and adjusted to bring its emission spectrum close to the spectrum of daylight (CIE coordinates: 1931 0.307; 0.376). Moreover, the light emission of these composites has been found to be temporally stable, which is due to the minimal structural instability and volume-uniform charge and energy transfer properties. Thus, the use of the synthesized polyfluorene-based organic ligands with controllable chemical structures adaptable to the structure of the polymer matrix can significantly increase the stability of white light emission from QD composites, which can be considered promising electroluminescent materials for fabrication of white QDLEDs.

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