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Abstract: New asymmetrically highly twisted anthracene derivatives serve as a matched host and guest material in high efficiency blue OLEDs. 2-(2-Methylnaphtathalene-1-yl)-9,10-di(naphthalene-2-yl)anthracene and N-(4-(10-naphthalene-2-yl)anthracene-9-yl)phenyl-N-phenylnaphthalene-2-amine were prepared as host material and as guest material, respectively. Multilayer organic electroluminecent devices constructed using these foregoing twisted anthracene derivatives as the emitting layer gave quantum efficiencies of 5% and exhibited a pure blue emission with CIE chromaticity coordinates x =0.15, y =0.14–0.18. [Copyright &y& Elsevier]

The electrical and optical properties of blue organic light-emitting devices (OLEDs) containing a mixed host emitting layer (EML) consisting of a 1,3-bis(carbazole-9-yl)benzene (mCP) layer and a 3-tert-butyl-9,10-di(naphtha-2-yl)anthracene (TBADN) layer were investigated. The driving voltage of the OLEDs with a mixed host EML was smaller than that of the OLEDs with a single EML. The electroluminescence spectra for OLEDs containing a mixed host EML showed a dominant peak related to the mCP or the TBADN layer. The color coordinates of the OLEDs containing a 5% TBADN-doped mCP EML were (0.146, 0.091), indicative of the deep blue color coordinates. [ABSTRACT FROM PUBLISHER]

Abstract: Luminescence efficiency of self-activated CaWO4 under 147nm vacuum ultraviolet (VUV) radiation excitation is about 90% of that of BaMgAl10O17:Eu2+ (BAM), the commercial blue plasma display panel (PDP) phosphor. However, the color purity and the particle size of the former needs substantial modification before it can be considered for application in PDP. CaWO4:Tm exhibits Tm3+ emission peaks in the blue region due to energy transfer from WO4 to Tm3+ ions but the overall emission intensity under 147nm excitation is reduced when compared to that of CaWO4. [Copyright &y& Elsevier]

Abstract: In this work, a series of electroluminescent (EL) devices based on trivalent europium (Eu3+) complex Eu(TTA)3phen (TTA=thenoyltrifluoroacetone, phen=1,10-phenanthroline) were fabricated by selecting 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) and tris(8-hydroxyquinoline) aluminum (Alq3) as hole block and electron transport materials, respectively. Interestingly, we found the transport of electrons decreases gradually with increasing thicknesses and evaporation rates of BCP and Alq3 layers. Analyzing carrier distribution and EL spectra, we conclude that appropriately modulating the thicknesses and evaporation rates is an efficient way to decrease the accumulation of electrons in HBL, thus suppressing the EL of hole block material. On the other hand, decreasing the transport of electrons can also facilitate the balance of holes and electrons on Eu(TTA)3phen molecules, thus further enhancing the EL efficiency. As a result, pure Eu3+ emission with the efficiency as high as 8.49cd/A was realized by controlling the thicknesses and evaporation rates of BCP and Alq3 layers to be 30nm and 0.10nm/s, 40nm and 0.10nm/s, respectively. [Copyright &y& Elsevier]

Abstract: The deep blue fluorescent spiro-type dopant materials N,N,N′,N′-tetraphenylspiro[fluorene-7,9′-benzofluorene] (SFBF)-5,9-diamine (BD-6DPA), N,N′-di-(2-naphthyl)-N,N′-diphenyl-SFBF-5,9-diamine (BD-6NPA), N,N′-diphenyl-N,N′-di-m-tolyl-SFBF-5,9-diamine (BD-6MDPA) and N,N′-diphenyl-N,N′-bis(4-(trimethylsilyl)phenyl)-SFBF-5,9-diamine (BD-6TMSA) were designed and successfully prepared by amination reactions. The EL characteristics of MADN as the blue host material doped with the above blue dopant materials were evaluated. The electroluminescence spectra of ITO/N,N′-diphenyl-N,N′-bis-[4-(phenyl-m-tolyl-amino)-phenyl]-biphenyl-4,4′-diamine (DNTPD/N,N′-di(1-naphthyl)-N,N′-diphenylbenzidine (NPB)/2-methyl-9,10-di(2-naphthyl)anthracene (MADN):BD-6MDPA/tris(8-hydroxyquinoline)aluminum (Alq3)/LiF/Al devices show a narrow emission band with a full width at half maximum of 48nm and a λ max(ε)=463nm. The device obtained from MADN doped with BD-6MDPA showed a good color purity (0.135, 0.156), high luminance efficiency (9.11cd/A at 6.5V) and high external quantum efficiency (8.16%). [ABSTRACT FROM AUTHOR]

Deep blue colored, fluorescent, spiro-type host materials, 5-[4-(1-naphthyl)phenyl]-spiro[fluorene-7,9¿-benzofluorene] and 5,9-bis[4-(1-naphthyl)phenyl]-spiro[fluorene-7,9¿-benzofluorene] were designed and successfully prepared by the Suzuki reaction. The electroluminescence characteristics of the two compounds as blue host materials doped with blue dopant materials, diphenyl[4-(2-[1,1;4,1]terphenyl-4-yl-vinyl)phenyl]amine and 1,6-bis[(p-trimethylsilylphenyl)amino]pyrene (SPP) were evaluated. The device used comprised ITO/N,N¿-bis-[4-(di-m-tolylamino)phenyl]-N,N¿-diphenylbiphenyl-4,4¿-diamine)/bis[N-(1-naphthyl)-N-phenyl]benzidine/Host:5% dopant/tris(8-hydroxyquinolinato)aluminium/Al¿LiF. The device obtained from 5-[4-(1-naphthyl)phenyl]-spiro[fluorene-7,9¿-benzofluorene] doped with 1,6-bis[(p-trimethylsilylphenyl)amino]pyrene displayed high color purity (0.138, 0.138) and high efficiency (3.70 cd/A at 7 V). [Copyright &y& Elsevier]

Abstract: New spiro-type 5-biphenyl-spiro[fluorene-7,9′-benzofluorene] (BH-1BP) and 5-diphenyl amine-spiro[fluorene-7,9′-benzofluorene] (BH-1DPA) were synthesized for use as blue organic light-emitting host and dopant materials, respectively. Their optical properties, including their UV absorption, photoluminescence and energy levels, were measured and blue OLEDs were made from them. The structure of the blue device is ITO/DNTPD/α-NPD/BH-1BP:5% dopant/Alq3 or ET4/Al–LiF. Here, α-NPD is used as the hole transport layer, DNTPD as the hole injection layer, BH-1DPA or diphenyl-[4-(2-[1,1;4,1]terphenyl-4-yl-vinyl)-phenyl]-amine (BD-1) as the blue dopant materials, Alq3 or ET4 as the transporting layer and Al as the cathode. The blue devices doped with 5% BH-1DPA and BD-1 show blue EL emissions at 444–448nm at 7V. A high efficiency of 3.28cd/A and the CIE coordinates (0.14, 0.11) at 7V can be achieved from the devices composed of BH-1BP:5% BD-1/ET4. [Copyright &y& Elsevier]

A novel, spiro-type host material 2-(10-naphthylanthracene)-spiro[fluorene-7,9′-benzofluorene] was prepared by reacting 2-bromo-spiro[fluorene-7,9′-benzofluorene] with 9-(2-naphthylanthracene)-10-boronic acid via the Suzuki reaction. 2-4′-(Phenyl-4-vinylbenzeneamine)phenyl-spiro[fluorene-7,9′-benzofluorene], 4-[2-naphthyl-4′(phenyl-4-vinylbenzeneamine)]phenyl and diphenyl-[4-(2-[1,1;4,1]terphenyl-4-yl-vinyl)-phenyl]-amine were used as dopant materials. Devices with the configuration of ITO/N,N′-bis[4-(di-m-tolylamino)phenyl]-N,N′-diphenylbiphenyl-4,4′-diamine)/bis[N-(1-naphthyl)-N-phenyl]benzidine/2-(10-naphthylanthracene)-spiro[fluorene-7,9-benzofluorene]:5% dopant/aluminum tris(8-hydroxyquinoline)/Al-LiF showed a maximum power efficiency of 3.7cd/A at 17.93mA/cm2 and a maximum luminance of 5018cd/m2 at 10V with a turn-on voltage of 4.5V. [Copyright &y& Elsevier]

This study features structural and photometric aspects of a down-converted green emanating erbium (Er3+) activated nanophosphor synthesized via a versatile and environmentally benign urea aided solution combustion procedure. The powder X-ray diffraction pattern (PXRD) of optimal sample SrGd 1.96 Er 0.04 Al 2 O 7 studied qualitatively by employing the Rietveld refinement practice, disclosed the tetragonal crystal phase with space group 14/mmm (139), consisting grains of size 50.03 nm. Surface morphology and grain size of nanopowders were well investigated by electron microscopy practices like scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). SEM micrograph gave clear insight that Er3+ doped nanophosphors possess slightly agglomerated particles with pores, voids and cracks due to high pressure breakout of gases while combustion synthesis. TEM and SEM images revealed the size of nanoparticles in the ambit of 40–60 nm which was in coherence with that obtained from the scherrer's equation, while the inter-fringes distance corresponding to diffraction plane (116) was calculated to be 0.27 nm from the HRTEM image. The desired nanophosphor showed brilliant green emission with an intense peak at 551 nm attributed to 4S 3/2 → 4I 15/2 transition of Er3+ ions, as analyzed through photoluminescent (PL) emission spectra monitored via near ultraviolet excitation wavelength (381 nm) with an optimal doping concentration of 2.0 mol%. Advanced photometric features like CIE color coordinates (0.3017, 0.6043), CCT (6032K), and color purity (76.52%) confirmed their green glow and are found to be in harmony with standard green emission. The study offers a luminous cool green emanating component for the fabrication of WLEDs and advanced optoelectronic appliances. [Display omitted] • SrGd 2 Al 2 O 7 :Er3+ nanophosphors were prepared via combustion procedure. • Absolute crystal phase was analyzed using XRD assisted Rietveld Refinement technique. • The new down-converted nanophosphors exhibit excellent green luminescence. • CIE chromaticity co-ordinates, CCT and color purity were inspected thoroughly. • Potential candidate for cool WLEDs, lasers and optical sensors. [ABSTRACT FROM AUTHOR]

• Reddish orange light emanating BaGd 2 ZnO 5 :Sm3+ nanocrystals fabricated for first time via solution combustion approach. • Refinement factors and crystal lattice parameters are computed for host and best luminescent composition. • The band-gap energy has been calculated using Kubelka-Munk function and further verified by Inokuti-Hirayama (I-H) model. • Versatile luminescent features have also been determined. • Widen new prospects for opto-electronic and solid state lighting applications. In the present report, a new series of Sm3+ doped BaGd 2 ZnO 5 nanomaterials emanating reddish orange light have been manufactured via an ecological, ideal and less energy consuming combustion methodology. Crystallographic investigation reports the orthorhombic symmetry type with Pbnm (62) space group. Morphological analysis examines the non-uniform agglomerated particles of 35-45 nm. Photoluminescent (PL) studies reveals about the orange red emanation from the fabricated nanomaterials by recording the PL emission spectrum, which shows a fine peak at 610 nm and also discloses that the exchange type interrelations as the main mechanism for non-radiative relaxation of energy, as validated by Inokuti-Hirayama (I-H) and Dexter's theory. Band gap, decay life time, quantum efficiency and non radiative rates of optimal powder were found as 4.84 eV, 0.607 ms, 87.84 % and 0.20 ms1, respectively. At the last, excellent luminescent performance is reflected in terms of CIE color parameters like color –coordinates (0.579, 0.420), color purity (78.88 %) and 1768 K color correlated temperature (CCT). These magnificent results certified the relevancy of the targeted nanocrystals as an auspicious agent in the manufacturing of advanced illuminating appliances like WLEDs, lasers, photonic devices, solar cell, sensors and various opto-electronic appliances. [Display omitted] [ABSTRACT FROM AUTHOR]

• Visible luminescence characteristics of Sm3+-doped borate-rich glasses are evaluated. • Sm3+: Li glass exhibits the highest emissions band intensity among all the glasses. • All Sm3+-doped glasses' CIE (x,y) and CCT values represent reddish-orange light region. • Obtained CP and LER values are varied within 98.04 99.75% and 365 383 lm/W ranges. • 7.093 × 10 22 cm2 & 12.46 nm are σ max em & Δ λ eff of 4G 5/2 →6H 7/2 transition in Sm3+: Li glass. [Display omitted] Optical absorption and visible luminescence aspects including visible emission decay times have been examined for six Sm3+ (1 mol%)-doped B 2 O 3 -rich glasses comprising single and mixed alkali oxides which were synthesized via melting-and-quenching approach. Upon intense λ exci. = 409 nm, fluorescence spectra displayed four bands peaked at 562 nm, 598 nm, 645 nm, and 706 nm owing to 4G 5/2 upper level to 6H 5/2 , 6H 7/2 , 6H 9/2 , and 6H 11/2 lower levels transitions respectively. Among identified emissions, orange fluorescence (598 nm) is found to be strong in all samples. Moreover Sm3+: Li ions having sample exhibits the dominant visible emissions band intensity in all samples, so for this sample, Judd–Ofelt (J O) analysis was carried out to calculate J O parameters Ω t (t = 2, 4, 6), and from them, radiative transition probabilities, branching ratios (calculated and experimental), and radiative lifetimes of Sm3+: 4G 5/2 level to distinct lower energy states were derived utilizing absorption and emission spectra. CIE (Commission Internationale de l′éclairage) coordinates, correlated color temperature (CCT), color purity, color rendering index, and luminous efficiency of radiation were determined from visible luminescence spectra of all studied glasses, and obtained CIE coordinates and CCT values lie in the reddish-orange light region of CIE diagram, indicating their potential for orange LEDs (light-emitting diodes) application. Here derived CCT values are lower than the typical warm light sources CCT limit (<3200 K). 4G 5/2 state luminescence decay patterns revealed double exponential behavior for assessing the measured lifetimes. Effective bandwidth, stimulated emission cross-section, and gain bandwidth were computed for observed luminescence transitions of Sm3+: Li ions possessing sample. [ABSTRACT FROM AUTHOR]

The performance of blue quantum dot light-emitting diode (QD-LED) device as one of the three primary color sources still lag behind that of red and green QD-LEDs. In this study, to obtain highly brightness, excellent color purity, and environmentally friendly blue-light-emitting materials for next generation display applications, we designed and synthesized ZnSeS quantum dots (GCS-QDs) from core Se–S composition-gradient to shell, in which the majority of Se resides close to the core domain and S dominantly locates outmost of the shells. The final GCS-QDs had a high quantum yield value of 78%, significantly narrow spectrum width of 12 nm, and reached an emission peak at 445 nm. Moreover, the blue-emitting QD-LED were fabricated by employing the GCS-QDs as light emitter, and the resulting device exhibited maximum brightness of 3,359 cd/m2, maximum current efficiency of 1.2 cd/A, maximum external efficiency of 3.5%, and full width at half maximum of only 16 nm at 448 nm). • High-quality blue ZnSeS QDs with a uniform alloy as an intermediate shell prepared. • These exhibited excellent crystallinity and fluorescent stability and possessed outstanding PL properties. • QY of 78% and FWHM of 12 nm at an emission of 445 nm. • Corresponding QLEDs exhibited a maximum brightness of 3,359 cd/m2, EQE of 3.5%, EL FWHM of 16 nm, and CIE of (0.157, 0.045). [ABSTRACT FROM AUTHOR]

Abstract: The novel spiro[fluorene-7,9′-benzofluorene]-based blue host material, 2-(10-phenylanthracene)-spiro[fluorene-7,9′-benzofluorene] (BH-3P), was successfully prepared by reacting 2-bromo-9,11-spiro[benzofluorene-fluorene] (3) with 9-phenylanthracene-10-boronic acid through the Suzuki reaction. Diphenyl-[4-(2-[1,1;4,1]terphenyl-4-yl-vinyl)-phenyl]-amine (BD-1), 2-[4′-(phenyl-4-vinylbenzeneamine)phenyl-spiro[fluorene-7,9′-benzofluorene] (BH-3BD) and 4-[2-naphthyl-4′ (phenyl-4-vinylbenzeneamine)]phenyl (BD-1N) were used as dopant materials. Blue OLEDs with the configuration of ITO/DNTPD/α-NPD/BH-3P:5% dopant/Alq3/Al–LiF were prepared from the BH-3P host and BD-1, BD-1N and BH-3BD dopants and they showed blue EL spectra at around 452nm at 7V and luminance efficiencies of 1.9–3.3cd/A. [Copyright &y& Elsevier]

Abstract: A new spiro-type compound, 2-(10-biphenylanthracene)-spiro[fluorene-7,9′-benzofluorene] (BH-3B) containing anthracene moiety was prepared for the blue host material. Also new dopant materials, 2-[4′-(phenyl-4-vinylbenzeneamine)phenyl-spiro[fluorene-7,9′-benzofluorene] (BH-3BD) and 4-[2-naphthyl-4′(phenyl-4-vinylbenzeneamine)]phenyl (BD-1N) were successfully synthesized and a blue OLEDs were made from them. The structure of the device was as follows; ITO/DNTPD/α-NPD/Host:5% dopant/Alq3/Al-LiF. Among all of the devices, the device obtained from BH-3B host doped with 5% BH-3BD showed the best electroluminescence characteristics. The emission peak of EL is at 456nm and the CIE value is (0.15,0.14). The brightness of the device is up to 5407cd/m2 at 10V with the maximum EL efficiency of 3.4cd/A. [Copyright &y& Elsevier]

Abstract: Novel spiro-type blue host material, 5-naphthyl-spiro[fluorene-7,9′-benzofluorene] (BH-1SN) and dopant material, 5-diphenyl amine-spiro[fluorene-7,9′-benzofluorene] (BH-1DPA) were successfully synthesized, and a blue OLED was made from them. The structure of the blue device is ITO/DNTPD/α-NPD/BH-1SN:5% dopant/Alq3 or ET4/Al–LiF. Here, α-NPD is used as the hole transport layer, DNTPD as the hole injection layer, BH-1DPA or BD-1 as the blue dopant materials, Alq3 or ET4 as the transporting layer and Al as the cathode. The blue devices doped with 5% BH-1DPA and BD-1 show blue EL emissions at 444 and 448nm at 7V, respectively, and a high efficiency of 3.4cd/A at 5V for the device was obtained from BH-1SN:5% BD-1/ET4. The CIE coordinates of the blue emission are 0.15, 0.08 at an applied voltage of 7V for the device obtained from BH-1SN/5% BH-1DPA/Alq3. [Copyright &y& Elsevier]

We demonstrate the simulation results of the radiation properties from top-emitting organic light-emitting devices (top-emitting OLEDs) with two- and three-microcavity structures based on the general electromagnetic theory. The parameters of the layer thickness and complex refractive index of each layer, the locations and density of the oscillating dipoles, and the emission photoluminescence spectrum are varied to optimize the device performance. In evaluating the deice performances, the output spectrum, the intensity distribution, and the viewing-angle characteristics of a top-emitting OLED are concerned. The simulation results are consistent with the Fabry-Perot cavity equation, which can be used as a guideline for designing a two-cavity top-emitting OLED. In such a design process, the dipole position is chosen first. Then the thicknesses of the whole organic layer, the semitransparent cathode, and the dielectric layer are adjusted for optimizing the device performance. In a three-cavity top-emitting OLED, not only the emission intensity and the viewing angle can be optimized at the same time, but also the emission wavelength can be independently tuned. Besides, the use of a three-cavity structure helps to narrow the spectral width and increase the color purity [ABSTRACT FROM PUBLISHER]

The phosphors of red (Y,Gd)BO3:Eu3+, green Zn2SiO4:Mn2+, and blue BaMgAl10O17:Eu2+ (BAM) are widely being used in plasma display panels (PDPs). However, BAM deteriorates seriously during the panel processing and operation, resulting in a loss of efficiency and color purity. Three aspects of the phosphors related to PDP applications are reviewed in this paper: degradation mechanisms of the blue phosphor under thermal treatment and vacuum ultraviolet (VUV) irradiation, the improvements for the currently-used phosphors, and the research of new phosphors. [ABSTRACT FROM PUBLISHER]

Abstract: We demonstrated blue organic light-emitting devices employing a novel blue-light-material, 2,5,2′,5′-tetrakis (4′-fluorostyryl) biphenyl as emitting layer. Maximum brightness and luminous efficiency were of 1828 cd/m2 at 9 V drive voltage and of 1.92 cd/A at 16 V. Commission Internationale de 1''Eclairage (CIE) coordinates are x =0.20 and y =0.22. The device color purity was further improved by introducing 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline as hole-blocking layer. Here, CIE coordinates are x =0.16 and y =0.20. A maximum brightness 1834 cd/m2 was achieved at 17 V. The peak current efficiencies was 1.52 cd/A at 10 V. [Copyright &y& Elsevier]

A series of high molecular weight, readily soluble copolymers of 9,9-dioctylfluorene with pyridine (less than or equal to 50 mol%) are synthesized by Suzuki polycondensation. Copolymers emit blue light and exhibit high PL efficiency. PL efficiencies show the maximum at 3,5-pyridine content of around 30 mol% in the copolymer. With further the increase of meta-linkage contents, PL efficiencies decrease rapidly to15% for alternating copolymer. Cyclic voltammetry investigation reveals that LUMO levels of copolymers increase with the increase of pyridine content. The introduction of pyridine unit at 3,5-position into polyfluorene backbone significantly depresses the excimer formation. The intensity of excimer emission decreases with the increase of 3,5-pyridine contents. Narrow and pure blue EL emission is obtained for copolymer with pyridine content of 40 mol%. External quantum efficiency is moderately high (0.4–0.5%) for such a pure blue emitter. The threshold voltages of devices from copolymers with the pyridine content of less than 40 mol% are low in the range of 5–6 V based on the device configuration: ITO/PEDOT/polymer/Ba/Al. The results indicate that fluorene-co-3,5-pyridine copolymers are promising blue-emitting electroluminescent materials. [Copyright &y& Elsevier]

[C5H5NC16H33][Eu(TTA)4] (TTA: 1-(2-thenoy)-3,3,3-trifluoracetate) is encapsulated in Si-MCM-41 which is modified with (3-chloropropyl)triethoxysilane and (1R,2R)-(−)-1,2-diaminocyclohexane. The XPS and IR spectra prove that the two organic molecules is grafted onto the surface of the channel of Si-MCM-41, UV-visible spectra and XPS of the rare earth (RE) complex and the assembly prove that the RE complex is dispersed in the channels of the chiral Si-MCM-41. Compared with the RE complex itself, the colour purity and the unit-mass luminescent intensity of the assembly are enhanced four times and twelve times, respectively. [Copyright &y& Elsevier]

Significant effort has been made in the exploration of Mn4+ activated red phosphor as a red component for the fabrication of white light emitting diodes (WLEDs) with superior performance (e.g., low correlated color temperature (CCT), high color render index (CRI)). Herein, the red luminescence of Sr 2 LaTaO 6 :Mn4+ phosphor was synthesized via high temperature solid state method. The crystal structure, luminescence behavior, and application in WLEDs of as-prepared phosphor were systematically investigated. The optimal Sr 2 LaTaO 6 :0.001Mn4+ phosphor showed a strong red emission with high color purity of 98.7 under the excitation wavelength of 316 nm, which is originated from the 2E g →4A 2 g transition of Mn4+ ion transition. Besides, the concentration quenching and thermal quenching phenomena were analyzed. Finally, by employing the Sr 2 LaTaO 6 :0.001Mn4+ phosphor as a red component for the fabrication of WLEDs, warm white lighting with a good CRI (91.45) and a low CCT (3859 K) could be achieved. Those findings suggested that the prepared Sr 2 LaTaO 6 : Mn4+ phosphor could be promising as a red component for the construction of good CRI warm-WLED devices [ABSTRACT FROM AUTHOR]

In this study, two natural small molecules, α-cyclodextrin (α-CD) and β-cyclodextrin (β-CD), are used as additives to improve the performance of quasi-2D PEA 2 Cs n -1 Pb n Br 3 n +1 ( n = 3, herein) PeLEDs. Both of them are shown to efficiently passivate the quasi-2D perovskite films to afford improved film quality and morphology, but they exhibit distinct phase regulation behaviors possibly due to their different pore sizes. It reveals that α-CD effectively suppresses the formation of the low- n phases ( n ≤ 2), while β-CD better regulates the phase with a medium- n value ( n = 3). Because of effectively suppressing the formation of low- n phases, the CD-assisted quasi-2D perovskite films possess facilitated exciton energy transfer and reduced nonradiative recombination. Consequently, the optimized α-CD-derived PeLED shows the highest luminance ( L max ) of 37,825 cd/m 2 with an external quantum efficiency (EQE) of 3.81%, while the β-CD-derived PeLED delivers a lower L max is enhanced by 6.3 and 3.8 times for α-CD- and β-CD-based PeLEDs, respectively, and EQE is enhanced by ∼4.8 times for both devices; besides, both CD-assisted devices also exhibit improved color purity and a lower bias dependency of electroluminescent intensity.2 with an EQE of 3.09%. Compared to the pristine device, L max is enhanced by 6.3 and 3.8 times for α-CD- and β-CD-based PeLEDs, respectively, and EQE is enhanced by ∼4.8 times for both devices; besides, both CD-assisted devices also exhibit improved color purity and a lower bias dependency of electroluminescent intensity.

Tin sulfide (SnS) is an earth-abundance material of non-toxic nature compared to commercially available quantum dots (QDs). Herein, a novel strategy is reported to improve the spectral tunability and stability of SnS/polyvinylpyrrolidone (PVP) core/shell QDs via microwave irradiation synthesis. Although PVP is used as a capping agent and passivating ligand for SnS QDs, as reported elsewhere, we take advantage of its polarity that allows good interaction with microwave irradiation, which impacts the nucleation and growth of SnS QDs. Furthermore, the amount of PVP in the precursor solutions controls the surface states and color purity of the QDs, and the obtained SnS/PVP QDs exhibit color-tunable emission light from blue to orange. The photoluminescence quantum yield reached the highest reported for SnS QDs, whereas 50% of their fluorescence intensity was maintained after 1-year storage at daylight. This approach provides a synthetic route to produce tunable and efficient colloidal QDs. A novel strategy using different polyvinylpyrrolidone (PVP) concentration to control the PVP shell thickness of SnS quantum dot cores, to improve the spectral tunability and stability of SnS/PVP core/shell QDs via microwave irradiation synthesis. With a range of diameters of those SnS/PVP core/shell QDs from 4.29 to 10.53 ​nm [Display omitted]. • Tuning of SnS QDs size by increasing PVP amount in microwave synthesis. • Color-tunable emission from blue to orange light under UV light by SnS/PVP QDs. • FRET is achieved through coupling the PVP chains with SnS cores, reached a high quantum yield. • The optimized PVP thickness gives high color purity and stability of SnS/PVP QDs. [ABSTRACT FROM AUTHOR]

A variety of optoelectronic devices such as photovoltaics and light-emitting diodes need stable performance of phosphors and the most important factor in liquid-crystal display (LCD) backlights will be the color purity. Here, a novel rare-earth-free narrow-band green-emitting phosphor based on the substitution of Mg2+ for Zn2+ in the lattice of Zn 3.98- x Mg x B 6 O 13 :0.02Mn2+ has been assembled via a solid-state reaction method. According to XRD and Rietveld refinement results, Zn 3.98- x Mg x B 6 O 13 :0.02Mn2+ can achieve perfect solid solution phases at 0 ≤ x ≤ 0.2 in terms of the same cubic structure of Zn 4 B 6 O 13 with space group I-43m (217). Under the excitation at 450 nm in blue region, Zn 3.98- x Mg x B 6 O 13 :0.02Mn2+ phosphors possess the green emission band at λ max ~542 nm and its full-width at half-maximum (FWHM) has been found to be only 39 nm. In addition, the emission intensity can be enhanced by increasing Mg content (x) from 0 to 0.1. It has to be mentioned that the thermal stability for the composition-optimized x = 0.1 sample is superior to that of the unsubstituted sample (x = 0). The underlying mechanism for this luminescence improvement has been verified. By virtue of assembling a green-emitting Zn 3·97 Mg 0·1 B 6 O 13 :0.02Mn2+ phosphor and a commercial red-emitting K 2 SiF 6 :Mn4+ phosphor as light converters, a warm white light has been achieved based on InGaN-based blue-LED (450 nm) and such device gives rise to wide color gamut of 105% National Television System Committee (NTSC) and good color-rendering index Ra of 90.6 at a correlated color temperature of 3683 K. Our results pave a new way in developing Mn2+-activated thermally stable narrow-band green-emitting phosphors with improving luminescence performance by simple compositional adjustments. • The color purity for green emission was improved. • Cation substitution strategy has been extensively explored. • Thermal stability was dramatically enhanced. [ABSTRACT FROM AUTHOR]

The host NaSrBi 2 (PO 4) 3 (abbreviated as NSBP) and the rare earth ions (RE3+) Dy3+/Sm3+/Eu3+ doped and codoped NSBP phosphors were prepared by a simple solid state reaction method. The phase identification and the morphological nature were studied by Powder XRD and HRSEM characterization tools respectively. The band gap of the host and RE3+ ions (Dy3+/Sm3+/Eu3+) doped phosphors were deduced from the diffused reflectance (DR) spectral data. The PLE spectra, the PL spectra and the energy transfer (ET) mechanism of Dy3+/Sm3+/Eu3+ doped and Dy3+-Sm3+, Dy3+-Eu3+ codoped NSBP phosphors were studied. The lifetime of the Dy3+/Sm3+/Eu3+ ions in NSBP was in the order of millisecond. The temperature dependent photoluminescence (TDPL) of the optimized phosphors were recorded from 23 °C to 210 °C, showed good thermal stability at 150 °C. The PL emission from the NSBP-xDy3+ phosphors found very closer to the ideal white region. The Sm3+ and Eu3+ doped NSBP phosphors exhibited excellent color coordinates and color purity when compared to the commercial phosphors. Combining the PL emission of the optimized NSBP-0.09Dy3+ phosphor with Sm3+ and Eu3+ ions separately, warm white emission was obtained when excited in the NUV region. Thus the prepared phosphors NSBP-0.09Dy3+,uSm3+ and NSBP-0.09Dy3+,vEu3+ might have promising applications in NUV excitable warm white light emitting diodes fabrication. • New eulytite NSBP-xDy/ySm/zEu and the Sm/Eu codoped NSBP-0.09Dy phosphors are prepared by solid state reaction method. • A narrow-band red emitting NaSrBi 2 (PO 4) 3 :Eu3+ phosphor showed good chromaticity, color purity and thermal stability. • NSBP-0.09Dy,uSm phosphors give warm white emission (CCT~3100 K) at λ ex =402 nm, favoring the indoor lighting applications. • Color tuning from cool white to warm white emission is possible when excited by near UV/blue LEDs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Phase-pure garnets based Y 3 Al 5 O 12 (YAG):Er3+ NPs have been developed via combustion technique. • Absolute YAG phase development has been confirmed via X-ray powder diffraction technique. • Down-conversion PL was thoroughly scrutinized via PL spectra, decay-time, QE and color parameters. • Potential candidate for optical-sensors, lasers and cool-WLEDs. New generation electro-optic appliances, mainly white-LEDs (light emitting diodes) foster excellent energy-efficacy, low cost, high lumen yield and environment friendly features. Y 3 Al 5 O 12 (YAG):Er3+ nanophosphors (NPs) have been developed via combustion technique. Owing to near-UV excitation (379 nm), vivid-green emission was acquired in the fabricated phosphor materials. The best possible luminous intensity has been ascertained at × = 0.02 Er3+content, with laudable quantum-efficiency (85.37%), suitable CCT (7246 K) and a high color-purity (82.30%). All the derived results predicate their effective performance in optical-sensors, lasers and cool-WLEDs. Moreover, the current findings can be protracted to develop other green-glimmering nanophosphors. [ABSTRACT FROM AUTHOR]

• Spherical SS with uniform distribution were prepared in ethanol via PLAL method. • Yield of such SS was enhanced via the transfer of colloidal NPs hydroxyls. • Colloidal Au-Ag N suspension showed significant physiochemical and optical traits. • Raman shift, size and fluorescence quantum yield of SS was evaluated. • The cinnamaldehyde enriched SS are potential for biomedical applications. Various bio-compatible nanostructures with strong fluorescence and tailored physiochemical properties are desirable for the biomedicine and bioelectronics applications. Based on this fact, we prepared some gold/silver-integrated cinnamon shell structure (SS) using the nanosecond pulse laser ablation in liquid (PLAL) method and characterized systematically. The structure, morphology, color purity, absorption and fluorescence properties of these SS were tuned via the laser parameters variation to determine their practical applications feasibility. The HRTEM images of the produced SS showed the nucleation of the face centered cubic nanocrystallites with growth orientation along (1 1 1) and (2 0 0) lattice planes. The XRD and thermogravimetric analysis of the as-prepared samples confirmed their crystalline nature and thermal stability, respectively. The EDX spectra and maps of the studied SS revealed their corresponding atomic compositions and distributions. The FTIR and Raman spectra displayed the existence of bimolecular residues within the SS. These plasmonic SS demonstrated very strong UV–Vis absorbance, high fluorescence quantum yield (0.055) and blue emission color purity (CCT and CIE coordinate of 2454.93 K and 0.164, 0.1033) at room temperature. The lifetime decay analyses showed significant decrease of the donor in the presence of the luminescent SS (6.5 ± 5.46 ns), attributing to the interplay of radiative energy transfer and subsequent emission of the photons at longer wavelength in the SS. It is established that the PLAL fabricated SS may be useful for the antimicrobial drugs formulation and biophotonic applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel Sm3+ ion-activated Sr 2 YSbO 6 phosphors were successfully prepared via the conventional solid-state reaction. • The concentration quenching and thermal quenching mechanisms were systematically investigated. • The novel Sm3+ ion-activated Sr 2 YSbO 6 phosphors exhibited an orange-red emission with the color purity of 66.66% and good thermal stability. The novel orange-emitting Sr 2 YSbO 6 :Sm3+ phosphors were synthesized in this work. The crystal structure, morphology, elemental composition, photoluminescence (PL) performances were investigated in detail. The Sr 2 YSbO 6 :Sm3+ phosphors was confirmed to possess the monoclinic phase with the space group of P 21/n by using the Rietveld refinement. The [SbO 6 octahedral would be made of one Sb5+ and six O2–, which would offer a relatively stable micro-structure. The optimal doping concentration was determined to be 5 mol% with the CIE chromatic coordinate of (0.583, 0.411) while the concentration quenching mechanism was dominated by the dipole–dipole interaction. It is worth noting that the emission intensity could remain about 78.11% at 423 K compared with its value at 303 K, suggesting that the resultant Sr 2 YSbO 6 :Sm3+ phosphors having good thermal stability which could be utilized for solid-state lighting. [ABSTRACT FROM AUTHOR]

[Display omitted] • BaZrO 3 :Sm3+ (1–9 mol %) nanopowders are synthesized by using the solution combustion route with Aloe vera gel as fuel. • PXRD results indicated the pure cubic phase and energy band gap vales are found to be in the range of 4.71–5.55 eV. • The obtained results exhibit reddish-orange color useful for w-LED applications. In this communication, we report the orange-red light emitting Sm3+ ions doped BaZrO 3 (BZO) nanopowders (NPs) prepared via green combustion synthesis route by utilizing the local available Aloe vera (AV) gel as the surfactant. For convenient to the readers, we represent BaZrO 3 :Sm3+ as BZOS. The cubic structure of the BZOS is confirmed by the results of powder X-ray diffraction (PXRD). The energy band gap values are studied by diffuse reflectance spectra (DRS) plots and found to be in the range of 4.71–5.55 eV. The spherical structure of the fabricated nanopowders is analyzed by means of scanning electron microscope (SEM) images. Transmission electron microscope (TEM) image are castoff to evaluate the particle size of the prepared powders. The crystallinity and interplanar distance are analyzed by selected area diffraction (SAED) and high-resolution TEM (HRTEM) images. The luminescence studies are performed at RT. The strong absorption in NUV spectral region is observed. Upon excitation at 403 nm wavelength the emission peaks centered at 565, 607 and 649 nm ascribed to Sm3+ ions 4f-4f characteristics. The explanation for this quenching of focus has been explored in depth. In the pure orange field, the pixel coordinates (0.579, 0.419) for improved BZO: Sm3+ phosphor lie. The CP levels are also calculated and observed to be ~ 90 percent. The quantum efficiency of the prepared nanopowders is found to be ~ 88. 62%. The above findings substantiate the ability of BZO: Sm3+ phosphor to be used in photovoltaic applications as a high thermal stability orange-red light producing element. [ABSTRACT FROM AUTHOR]