Potassium and Rubidium Copper Halide A2CuX3 (A = K, Rb, X = Cl, Br) Micro- and Nanocrystals with Near Unity Quantum Yields for White Light Applications

2021 ◽  
Author(s):  
Zhicong Zhou ◽  
Yanyan Li ◽  
Zengshan Xing ◽  
Zhi Li ◽  
Kam Sing Wong ◽  
...  
Keyword(s):  
White Light ◽  
Quantum Yields ◽  
Copper Halide

scholarly journals Photoactivated cell-killing amino-based flavylium compounds

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hélder Oliveira ◽  
Paula Araújo ◽  
Ana Rita Pereira ◽  
Nuno Mateus ◽  
Victor de Freitas ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Singlet Oxygen ◽  
White Light ◽  
Structural Features ◽  
Cellular Damage ◽  
Quantum Yields ◽  
Type I ◽  
Fluorescence Quantum Yields ◽  
Skin Cells ◽  
Structure Activity

AbstractPhotodynamic therapy (PDT) is a well-established therapeutic for the treatment of different diseases. The growing interest of this technique required the development of new photosensitizers with better photo-features. This work reports the study of the potential of five nature-inspired amino-based flavylium compounds with different structural features as photosensitizers towards topical PDT. In terms of dark cytotoxicity the five pigments were tested towards confluent skin cells in both fibroblasts and keratinocytes. In the range of concentrations tested (6.3–100 μM), keratinocytes were more prone to growth inhibition and the IC50 values for 5OH4′NMe2, 7NEt2st4′NMe2 and 7NEt24′NH2 were determined to be 47.3 ± 0.3 μM; 91.0 ± 0.8 μM and 29.8 ± 0.8 μM, respectively. 7NEt24′NMe2, 7NEt2st4′NMe2 and 7NEt24′NH2 showed significant fluorescence quantum yields (from 3.40 to 20.20%) and production of singlet oxygen (1O2). These latter chromophores presented IC50 values of growth inhibition of keratinocytes between 0.9 and 1.5 µM, after 10 min of photoactivation with white light. This cellular damage in keratinocyte cells upon white light activation was accompanied with the production of reactive oxygen species (ROS). It was also found that the compounds can induce damage by either type I (ROS production) or type II (singlet oxygen) PDT mechanism, although a higher cell survival was observed in the presence of 1O2 quenchers. Overall, a structure–activity relationship could be established, ranking the most important functional groups for the photoactivation efficiency as follows: C7-diethylamino > C4′-dimethylamino > C2-styryl.

scholarly journals Aqueous Synthesis of ZnSe/ZnS-2-R-Benzothiazole Nanocrystals with White Emission

2016 ◽  
Vol 2016 ◽  
pp. 1-9
Author(s):  
Ying-Fan Liu ◽  
Yan-Hui Zhang ◽  
Guo-Qing Wang ◽  
Kai-Ming Mao ◽  
Shao-Ming Fang ◽  
...  
Keyword(s):  
White Light ◽  
Light Emitting Diodes ◽  
Water Soluble ◽  
Quantum Yields ◽  
Aqueous Synthesis ◽  
Light Emitting ◽  
White Emission ◽  
White Light Emitting Diodes ◽  
Nm Range

We prepared water-soluble white light-emitting ZnSe/ZnS-2-R-benzothiazole nanocrystals (NCs), R = 2-hydroxy-5-(2,5-dimethyl-thienyl)-phenyl. The penicillamine (Pen) capped ZnSe/ZnS NCs were firstly prepared with high photoluminescence quantum yields (PL QY) of 40%. Then they bond to 2-R-benzothiazole molecules, resulting in white light-emitting ZnSe/ZnS-2-R-benzothiazole NCs with QY of 75% over a 375 to 650 nm range of emission, which can be applied to white light-emitting diodes. The ZnSe/ZnS-2-R-benzothiazole NCs with two emission bands at around 451 and 557 nm were discussed and the possible mechanism of the interaction of ZnSe/ZnS NCs with 2-R-benzothiazole was also proposed.

scholarly journals A Versatile Tripodal Ligand for Sensitizing Lanthanide (LnIII) Ions and Color Tuning

Chemistry ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 138-145
Author(s):  
Rodney A. Tigaa ◽  
Raul E. Ortega ◽  
Xinsong Lin ◽  
Geoffrey F. Strouse
Keyword(s):  
Quantum Yield ◽  
Metal Complexes ◽  
White Light ◽  
Single Component ◽  
Quantum Yields ◽  
Color Tuning ◽  
Tripodal Ligand ◽  
Light Emitting ◽  
The Absolute ◽  
White Material

Lanthanide (LnIII) ions were successfully chelated and sensitized with a tripodal ligand. The absolute LnIII-centered emission efficiencies were ~3% for both the europium(III) (EuIII) and terbium (TbIII) complexes and up to 54% for the cerium(III) (CeIII) complex. The differences in emission quantum yields for the early lanthanides (CeIII) and the mid lanthanides (EuIII and TbIII) were attributed to their d–f and f–f nature, respectively. Despite the low quantum yield of the EuIII complex, the combination of the residual ligand fluorescence and the red EuIII emission resulted in a bluish-white material with the Commission Internationale de l’Eclairage (CIE) coordinates (0.258, 0.242). Thus, metal complexes of the ligand could be used in the generation of single-component white-light-emitting materials.

The application of Zn0.8Cd0.2S nanocrystals in white light emitting diodes devices

RSC Advances ◽  
2015 ◽  
Vol 5 (106) ◽  
pp. 87667-87671 ◽  
Author(s):  
Ya-Ching Chen ◽  
Cyuan-Bin Siao ◽  
Hong-Shuo Chen ◽  
Kuan-Wen Wang ◽  
Shu-Ru Chung
Keyword(s):  
White Light ◽  
Light Emitting Diodes ◽  
Quantum Yields ◽  
Light Emitting ◽  
High Quantum ◽  
Ternary Semiconductor ◽  
White Light Emitting Diodes

In this study, colloidal ternary semiconductor Zn0.8Cd0.2S (ZnCdS) nanocrystals (NCs) with wide emission and high quantum yields (QYs) have been prepared and used as nanophosphors in white light emitting diodes (WLEDs).

scholarly journals White-Light Emitting Di-Ureasil Hybrids

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2246 ◽  
Author(s):  
Ming Fang ◽  
Lianshe Fu ◽  
Rute Ferreira ◽  
Luís Carlos
Keyword(s):  
White Light ◽  
Light Emission ◽  
Relative Concentration ◽  
Sol Gel ◽  
Quantum Yields ◽  
Excitation Wavelength ◽  
Light Sources ◽  
Efficient Energy Transfer ◽  
Visible Absorption ◽  
Light Emitting

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.

Efficient and tunable multi-color and white light Ln-MOFs with high luminescence quantum yields

RSC Advances ◽  
2015 ◽  
Vol 5 (44) ◽  
pp. 34936-34941 ◽  
Author(s):  
Shuzhi Zou ◽  
Qipeng Li ◽  
Shaowu Du
Keyword(s):  
Quantum Yield ◽  
White Light ◽  
Light Emission ◽  
White Light Emission ◽  
Quantum Yields

Multi-color luminescent Ln-MOFs were synthesized and a white light-emission with a quantum yield up to 32% was achieved.

scholarly journals Excellent color rendering index single system white light emitting carbon dots for next generation lighting devices

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Manasa Perikala ◽  
Asha Bhardwaj
Keyword(s):  
White Light ◽  
Carbon Dots ◽  
Quantum Yields ◽  
Single System ◽  
Light Emitting ◽  
Color Rendering Index ◽  
Different Color ◽  
Color Rendering ◽  
Excellent Color ◽  
Emission Bandwidth

AbstractRecently, quantum dots (QDs) are finding enormous application in white light emitting diodes (WLEDs) and WLEDs with high color rendition are in high demand. QD-WLEDs use different color (Red, Blue, Green) emitting QDs to obtain white light. Use of different color emitting QDs affect purity of white light due to self-absorption losses and QD degradation, in the long run affecting color rendering index (CRI) of WLEDs. Herein, we report low cost, environment friendly, open air atmosphere synthesis of single system white light emitting carbon dots (CDs) with broad emission bandwidth ranging 116 –143 nm and quantum yields (QY) ~ 5 – 13 % in colloidal state by modifying CD surface. Furthermore, carbon dot polymer phosphor (CD-PDMS phosphor) is fabricated which emits white light under UV illumination with a record emission bandwidth of ~ 154 nm and QY ~ 16 % in solid state. Moreover, CD-PDMS phosphor exhibit excellent color rendering index (CRI) ~ 96, the highest reported so far with CIE co-ordinates (0.31, 0.33) that are quite akin to pure white light. Such high performances are achieved due to high quality of CDs and CD-PDMS polymer phosphors by precise control in passivation/functionalization of nanoparticle surface. This work will set platform for the application of CD-phosphor based WLEDs in lighting systems.

scholarly journals Stable blue-emissive aluminum acetylacetonate nanocrystals with high quantum yield of over 80% and embedded in polymer matrix for remote UV-pumped white light–emitting diodes

Nanophotonics ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 1509-1518
Author(s):  
Hong Zheng ◽  
Bingkun Chen ◽  
Lifu Shi ◽  
Fa Zhang ◽  
Ziheng Zhao ◽  
...  
Keyword(s):  
Composite Film ◽  
White Light ◽  
Light Emitting Diodes ◽  
Composite Films ◽  
Blue Emission ◽  
Quantum Yields ◽  
Aluminum Compound ◽  
Light Emitting ◽  
Air Atmosphere ◽  
White Light Emitting Diodes

AbstractBlue-emissive nanocrystals (NCs) with high photoluminescence quantum yields (PL QYs) and excellent stability are essential for lighting and displays. Here, a facile top-down approach (including two steps: thermal annealing and ultrasonic treatment) by using aluminum acetylacetonate (Al(acac)3) as a precursor is adopted to fabricate blue-emissive Al(acac)3 NCs with high PL QY reaching 81.8%, the highest reported value for the aluminum compound-based NCs so far. Additionally, the as-fabricated Al(acac)3 NC solution (in toluene) exhibits high stability under air atmosphere condition, maintaining 61.2% of initial PL QY after 1 year. Furthermore, solution-processed Al(acac)3 NCs/poly(methyl methacrylate) (PMMA) composite film with blue emission is demonstrated. Finally, combinations of the blue-emitting Al(acac)3 NCs/PMMA composite film with red-emitting and green-emitting CuInS2 composite films are realized, resulting in remote ultraviolet-pumped white light-emitting diodes with a high color rendering index of 91. These findings inform new blue-emissive NCs and composite films, potentially paving the way to design new structures of lighting and display devices.

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

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.

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

2015 ◽  
Vol 3 (17) ◽  
pp. 4553-4562 ◽  
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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