Quadrupolar π-Gels: Sol–Gel Tunable Red–Green–Blue Emission in Donor–Acceptor-Type Oligo(p-phenylenevinylene)s

2007 ◽  
Vol 19 (3) ◽  
pp. 411-415 ◽  
Author(s):  
A. Ajayaghosh ◽  
V. K. Praveen ◽  
S. Srinivasan ◽  
R. Varghese
Keyword(s):  
Sol Gel ◽  
Blue Emission ◽  
Donor Acceptor

Blue Emitting BaAl2O4:Ce3+ Nanophosphors with High Color Purity and Brightness for White LEDs

2019 ◽  
Vol 25 (6) ◽  
pp. 1466-1470 ◽  
Author(s):  
Rituparna Chatterjee ◽  
Subhajit Saha ◽  
Karamjyoti Panigrahi ◽  
Uttam Kumar Ghorai ◽  
Gopes Chandra Das ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Field Emission ◽  
Sol Gel ◽  
Blue Emission ◽  
Diffraction Field ◽  
White Leds ◽  
Display Devices ◽  
Transmission Electron ◽  
Structure Morphology ◽  
The Impact

AbstractIn this work, strongly blue emitting Ce3+-activated BaAl2O4 nanophosphors were successfully synthesized by a sol–gel technique. The crystal structure, morphology, and microstructure of the nanophosphors have been studied by X-ray powder diffraction, field emission scanning electron microscopy, and high-resolution transmission electron microscopy. The photoluminescence spectra show the impact of concentration variation of Ce3+ on the photoluminescence emission of the phosphor. These nanophosphors display intense blue emission peaking at 422 nm generated by the Ce3+ 5d → 4f transition under 350 nm excitation. Our results reveal that this nanophosphor has the capability to take part in the emergent domain of solid-state lighting and field-emission display devices.

Efficient deep-blue non-doped organic light-emitting diode with improved roll-off of efficiency based on hybrid local and charge-transfer excited state

RSC Advances ◽  
2016 ◽  
Vol 6 (74) ◽  
pp. 70085-70090 ◽  
Author(s):  
Haichao Liu ◽  
Qing Bai ◽  
Weijun Li ◽  
Yachen Guo ◽  
Liang Yao ◽  
...  
Keyword(s):  
Excited State ◽  
High Efficiency ◽  
Light Emitting Diode ◽  
Blue Emission ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Deep Blue ◽  
Organic Light ◽  
Slow Roll ◽  
Donor Acceptor

Acceptor–donor–acceptor triphenylamine–phenanthroimidazole derivate (TPA–2PPI) servers as an emitter, whose device exhibits deep-blue emission, high efficiency and slow roll-off of efficiency.

Nanosized LiSrPO4:Eu2+ phosphor with blue-emission synthesized by the sol–gel method

2007 ◽  
Vol 103 (2-3) ◽  
pp. 415-418 ◽  
Author(s):  
Z.C. Wu ◽  
J.X. Shi ◽  
M.L. Gong ◽  
J. Wang ◽  
Q. Su
Keyword(s):  
Sol Gel ◽  
Blue Emission ◽  
Gel Method ◽  
Sol Gel Method

scholarly journals Time Resolved Photoluminescence of Cubic Mg Doped GaN

1999 ◽  
Vol 572 ◽  
Author(s):  
R. Seitz ◽  
C. Gaspar ◽  
T. Monteiro ◽  
E. Pereira ◽  
B. Schoettker ◽  
...  
Keyword(s):  
Blue Emission ◽  
Spectral Shift ◽  
Excitation Density ◽  
Acceptor Pair ◽  
Time Resolved ◽  
Deep Donor ◽  
Cubic Gan ◽  
Donor Acceptor ◽  
Time Resolved Photoluminescence ◽  
Mg Doped

ABSTRACTMg doped cubic GaN layers were studied by steady state and time resolved photoluminescence. The blue emission due to Mg doping can be decomposed in three bands. The decay curves and the spectral shift with time delays indicates donor-acceptor pair behaviour. This can be confirmed by excitation density dependent measurements. Furthermore temperature dependent analysis shows that the three emissions have one impurity in common. We propose that this is an acceptor level related to the Mg incorporation and the three deep donor levels are due to compensation effects.

Luminescence of SrY2O4:Eu3+ associated with defects

2010 ◽  
Vol 25 (11) ◽  
pp. 2120-2124 ◽  
Author(s):  
Jia Zhang ◽  
Yuhua Wang
Keyword(s):  
Solid State ◽  
Solid State Reaction ◽  
Vacuum Ultraviolet ◽  
Sol Gel ◽  
Blue Emission ◽  
Solid State Reaction Method ◽  
Excitation Spectra ◽  
Blue Emission Band ◽  
Gel Method ◽  
Sol Gel Method

SrY2O4:Eu3+ phosphors were synthesized by both the solid-state reaction method and the sol-gel method, and their photoluminescence in vacuum ultraviolet (VUV) and the ultraviolet (UV) region were evaluated. The excitation spectra of SrY2O4:Eu3+ phosphors prepared by solid-state reaction show another excitation band centered at 324 nm except for the charge-transfer bands (CTB) of Eu3+ when monitored at 610 nm, and a blue emission band around 406 nm is observed when excited at 324 nm, which could be associated with defects. Both the excitation and emission bands mentioned above disappear when the samples were prepared by the sol-gel method. SrY1.98O4:0.02Eu3+ phosphors synthesized by the sol-gel method exhibit a higher emission intensity under 147 nm excitation compared with solid-state reaction technology. The main reason could be that the samples prepared by the solution-based route have more regular and uniform morphologies.

Synthesis and characterization of sol-gel derived hexa-aluminate phosphors

1997 ◽  
Vol 12 (3) ◽  
pp. 819-824 ◽  
Author(s):  
D. Ravichandran ◽  
R. Roy ◽  
W. B. White ◽  
S. Erdei
Keyword(s):  
Sol Gel ◽  
Broad Band ◽  
Blue Emission ◽  
Emission Spectra ◽  
Steam Treatment ◽  
Optical Pyrometer ◽  
Processing Route ◽  
Sol Gel Process ◽  
State Processing

Two refractory phosphors, BaMg2Al16O27: Eu2+ (BAM) and MgAl11O17.5: Ce3+, Tb3+ (MAO), have been synthesized both by the conventional solid-state processing route (using oxides as the starting materials) and by reacting precursors made by the sol-gel process using organic precursors. The phases formed were reacted at 1000 °C in (a) steam and (b) steam + AlF3. The phosphors were well crystallized with particle sizes in the range of 1–10 μm. The emission spectra showed the characteristic broad band blue emission of Eu2+ for BAM and a narrow band green luminescence of Tb3+ for MAO. The melting points of BAM and MAO were measured to be 1920 ± 20 °C and 1950 ± 20 °C, respectively, using an Ir-strip furnace and optical pyrometer. BAM and MAO phosphor materials are congruently and incongruently melting, respectively. Excellent crystallization via the sol-gel route was found even at 1220 °C. Enhancement of the luminescent output by the steam treatment by some 25% was determined.

Optical properties of ZnO nanoparticles synthesized by varying the sodium hydroxide to zinc acetate molar ratios using a Sol-Gel process

Open Physics ◽  
2011 ◽  
Vol 9 (5) ◽  
Author(s):  
Francis Dejene ◽  
Abdub Ali ◽  
Hendrik Swart ◽  
Reinhardt Botha ◽  
Kittesa Roro ◽  
...  
Keyword(s):  
Zno Nanoparticles ◽  
Sol Gel ◽  
Visible Region ◽  
Blue Emission ◽  
Molar Ratio ◽  
Broad Emission Band ◽  
Photoluminescence Intensity ◽  
Molar Ratios ◽  
Quantum Confinement Effects ◽  
Sol Gel Process

AbstractMaterial property dependence on the OH−/Zn2+ molar ratio of the precursor was investigated by varying the amount of NaOH during synthesis of ZnO. It was necessary to control the water content and temperature of the mixture to ensure the reproducibility. It was observed that the structural properties, particle size, photoluminescence intensity and wavelength of maximum intensity were influenced by the molar ratio of the precursor. The XRD spectra for ZnO nanoparticles show the entire peaks corresponding to the various planes of wurtzite ZnO, indicating a single phase. UV measurements show the absorption that comes from the ZnO nanoparticles in visible region. The absorption edge of these ZnO nanoparticles are shifted to higher energies and the determined band gap energies are blue shifted as the OH−/Zn2 molar ration increases, due to the quantum confinement effects. The photoluminescence characterization of the ZnO nanostructures exhibited a broad emission band centred at green (600 nm) region for all molar ratios except for OH−/Zn2+ = 1.7 where a second blue emission around 468 nm was also observed. The photoluminescence properties of ZnO nanoparticles were largely determined by the size and surface properties of the nanoparticles.

Effect of the Sols’ Zinc Ions’ Concentration on Structural and Optical Properties of (Cu, Al) Co-Doped ZnO Thin Film by Sol - Gel Method

2014 ◽  
Vol 496-500 ◽  
pp. 206-209
Author(s):  
Ying Xiang Yang ◽  
Hong Lin Tan ◽  
Qing Nan Shi
Keyword(s):  
Sol Gel ◽  
Blue Emission ◽  
Electron Transition ◽  
Photoluminescence Spectra ◽  
Zinc Vacancy ◽  
Structural And Optical Properties ◽  
Gel Method ◽  
Sol Gel Method ◽  
Doped Zno ◽  
Co Doped

(Cu-Al) co-doped ZnO thin films were deposited on glass substrate by the sol-gel method using the spin coating technique.The crystalline phase structure of the films were analyzed by X-raydiffraction.The photoluminescence spectra of samples were measured by fluorescence spectrophotometer.The results show that these films have a compact hexagonal wurtzitetype structure. five peaks have been observed from the PL spectra of the all samples,367nm (3.38eV),398nm (3.12eV),450nm (2.759eV),483nm (2.57eV) and 468nm (2.653eV).It is concluded that the violet peak may correspond to the excit on emission,the blue emission corresponds to the electron transition from the bottom of the conduction band to the accept or level of zinc vacancy.

scholarly journals On the origin of the 2.8 eV blue emission in p-type GaN:Mg : A time-resolved photoluminescence investigation

2001 ◽  
Vol 6 ◽  
Author(s):  
F. Shahedipour ◽  
B.W. Wessels
Keyword(s):  
Luminescence Intensity ◽  
Random Distribution ◽  
Blue Emission ◽  
Acceptor Pair ◽  
Time Resolved ◽  
Donor Acceptor ◽  
Shallow Acceptors ◽  
Donor Acceptor Pair ◽  
P Type ◽  
Time Resolved Photoluminescence

The decay dynamics of the 2.8 eV emission band in p-type GaN was investigated using time-resolved photoluminescence spectroscopy. The luminescence intensity decays non-exponentially. The decay dynamics were consistent with donor-acceptor pair recombination for a random distribution of pair distances. Calculations using the Thomas-Hopfield model indicated that recombination involves deep donors and shallow acceptors.

Tailored TiO2 Nanorod Arrays for Dye Sensitized Solar Cell Applications

2021 ◽  
Author(s):  
Jeba Beula R ◽  
Suganthi Devadason ◽  
Abiram A ◽  
Vidhya B
Keyword(s):  
Solar Cell ◽  
Seed Layer ◽  
Sol Gel ◽  
Blue Emission ◽  
Photo Luminescence ◽  
Dye Sensitized Solar Cell ◽  
Luminescence Spectra ◽  
Step Method ◽  
Blue Emission Band ◽  
Dye Sensitized

A TiO2 layer using titanium (IV) butoxide on fluorine doped tin oxide (FTO) substrate is used as a seed layer for the growth of 2D-TiO2 arrays (TRA). TRAs with length of ~1 to 2 µm were grown on seed layer (SL) by two step method. In the first step TiO2 SLs were deposited by sol-gel assisted spin coating method and the second step involved the typical hydrothermal technique to grow rutile TRAs. Most of the TRAs grown on FTO substrate without SL were randomly oriented and TRAs with 0.025M SL was oriented vertically from the substrate. Whereas TRAs grown on 0.05M SL showed hierarchical nanoflower clusters composed of a bunch of TRAs as petals blooming to all directions from the core. The XRD pattern showed all the three TRAs to be crystallized in a tetragonal rutile phase. Photo Luminescence spectra revealed that the TRAs on 0.05M SL have comparatively low intense blue emission band, predicting the suppressed electron-hole recombination rate. The power conversion efficiency of the dye sensitized solar cell (DSSC) with TRAs grown on 0.05M SL was recorded as 3%, which is 3 times greater than that without SL and 1.6 times greater than that with 0.025M SL in our observations.

Sign in / Sign up

Export Citation Format

Share Document