Decrease In Emission Intensity Research Articles

Effects of Mg2+/Si4+ doping on luminescence of Y3Al5O12:Ce3+ phosphors

A series of Mg2+/Si4+ codoped Y3Al5O12:Ce3+ phosphors were synthesized by a sol-gel method. X-ray diffraction, scanning election microscope, energy dispersive spectroscopy and fluorescent spectrophotometer were used to characterize the synthesized phosphors. The influence of codoped Mg2+/Si4+ ions on luminescence of Y3Al5O12:Ce3+ was investigated. The X-ray diffraction, scanning election microscope and energy dispersive spectroscopy results indicate that Ce3+, Mg2+ and Si4+ substitute Y3+ site, Al13+ in the octahedral site and Al23+ in the tetrahedral site and the substitution has no obvious influence on the phase and microstructure. And the Mg2+/Si4+ substitution leads to the red shift of emission band and the decrease of emission intensity.

Visualization of icing of supercooled water using Tb(III)-based temperature-sensitive paint

Visualization of icing processes of supercooled water is reported. Tb(hfa)3(tppo)2 composed of a Tb(III) ion, triphenylphosphine oxide (tppo), and hexafluoroacetylacetonato (hfa) ligands was coated on an aluminum surface using silicon grease/n-hexane medium for temperature-sensitive luminescent paint. The prepared Tb(III)-based sensor was characterized by temperature-dependent emission spectral measurements. The icing processes of a supercooled water droplet were observed using a high-speed camera. The time-dependent images clearly showed the water/ice phase change from an original point of physical stimulation to entire droplet. The emission intensity decrease was responsible for the heat-assisted back energy transfer from Tb(III) ions to hfa ligands due to the latent-heat release during the icing processes.

Highly Sensitive Ratiometric Fluorescent Detection of Indium(III) Using Fluorescent Probe Based on Phosphoserine as a Receptor.

Indium is one of the most widely used scarce metals for manufacturing various electronic devices including notebooks, mobile phones, and PC monitors. Recent studies revealed that indium and its compound could cause several toxicities to human beings and animals. However, there is no report about ratiometric fluorescent detection of In(III) in aqueous solutions. We synthesized a fluorescent probe (1) for In(III) based on a phosphoserine as a receptor with a pyrene fluorophore using solid phase synthesis. 1 showed highly sensitive ratiometric response to In(III) in purely aqueous solutions by increasing excimer emission intensity at 476 nm with a concomitant decrease in monomer emission intensity at 395 nm. 1 showed sensitive ratiometric responses to In(III) over a wide range of pH (2 < pH < 8) and exhibited a highly selective ratiometric response to In(III) among 18 tested metal including Al(III) and Ga(III). Job's plot analysis indicated that 1 preferred to form a 2:1 complex with In(III) and the binding affinity for In(III) was measured to be 2.3 × 1012 M-2 ( R2 = 0.989). 1 showed linear ratiometric responses to nanomolar concentrations (0-750 nM) of In(III) and the detection limit was calculated to be 64 nM ( R2 = 0.992) in aqueous solution. The binding mode study using NMR, IR, and CD spectroscopies revealed that the phosphate and the amide groups of the receptor of 1 played an important role for the binding with In(III). Moreover, 1 was suitable for the ratiometric detection of In(III) in tap water and groundwater. 1 showed much better detection properties than those of the colorimetric methods using EDTA with Eriochrome black T (EBT) and 4-(2-pyridylazo) resorcinol (PAR) for the detection of In(III) in tap water and groundwater.

Influence of Mg2+/Ga3+ doping on luminescence of Y3Al5O12:Ce3+ phosphors

Mg2+/Ga3+ doped Y3Al5O12:Ce3+ phosphors were synthesized through a solid state reaction. The phase and luminescent of the synthesized phosphors were investigated. For Ga3+ codoped Y2.96Ce0.04Al(5−x)GaxO12 phosphors, the emission intensity increases with the increase of Ga3+ concentration up to Y2.96Ce0.04Al4.80Ga0.20O12 and then decreases with a further increase of Ga3+ concentration, but the emission peak shifts to shorter wavelength continuously in the Ga3+ doping concentration range of 0.05–0.25. For Mg2+/Ga3+ codoped Y2.96Ce0.04Al(4.8−y)Ga0.20MgyO12 phosphors, the emission intensity decreases and the emission peak shifts to longer wavelength continuously in the Mg2+ doping concentration range of 0.02–0.12. The emission spectra of Y2.96Ce0.04Al(4.8−y)Ga0.20MgyO12 phosphors demonstrate that the codoped Mg2+/Ga3+ ions not only induce the enhancement of Y2.96Ce0.04Al5O12 emission intensity but also lead to the red shift of Y2.96Ce0.04Al5O12 emission peak. The decay lifetimes decrease in Mg2+/Ga3+ codoped Y2.96Ce0.04Al5O12 phosphors due to defects formed by substitutions of Y3+ by Mg2+/Ga3+.

The consistency of China's energy statistics and its implications for climate policy

Reliable energy statistics serve as the foundation and starting point for understanding the climate policies of any country. As the most comprehensive sources of energy data for China, China Energy Statistics Yearbooks (ESY), published by the National Bureau of Statistics (NBS), underwent three major revisions since 2005. This paper analyzes how these three major revisions correspond to data on China's energy use from 1996 to 2012, and theirs impacts on CO2 emissions, emission intensity and the share of non-fossil energy in total energy consumption, which are key indicators of China's climate policies. Some notable changes include CO2 emissions for 2012, which increased by 594 Million tons – a figure equivalent to South Korea's annual emissions, which implies that China's emissions at peak level will be higher than previous estimation. Meanwhile, revised emission intensity data show a higher amount and lower decreasing rate, which means that China's achievements in decreasing emission intensity during 2005–2012 have been overestimated, while future difficulties for achieving the goal of 40–45% reduction will be greater. On the share of non-fossil fuel energy in China's total energy mix, the adjustments increased the indicator by 1.26%, reflecting the fact that China's effort in developing non-fossil energy had been underestimated. Discrepancies in reported scattered coal in different statistics versions are the main contributors to these changes. To further enhance the reliability of its energy statistics, and thereby its climate policies, China should remove incentives for misreporting through legal means, and make the technical system for data collection more comprehensive and accurate, with particular emphasis on scattered coal.

A novel chromone and rhodamine derivative as fluorescent probe for the detection of Zn(II) and Al(III) based on two different mechanisms

In this study, a novel fluorescent probe, 6‑hydroxychromone‑3‑carbaldehyde‑(rhodamine B carbonyl) hydrazine (L), for Zn2+ and Al3+ was designed and synthesized. Initially, this probe L exhibited inferior fluorescence emission peak centered at 488 nm in EtOH/HEPES solution (3/1, 10.0 μM HEPES, pH 7.4) when excited at 421 nm. After the addition of Zn2+, this probe L displayed excellent selectivity towards Zn2+ with obvious fluorescence color change from colorless to yellow, which might be attributed to the formation of a 1:1 ligand-metal complex resulting in the inhibition of photo-induced electron transfer phenomenon. Whereas, the prepared Zn2+ complex of L could be used as a ratiometric fluorescent probe to detect Al3+ on the basis of fluorescence resonance energy transfer mechanism. This ligand-metal complex of Zn2+ (LZn) showed high selectivity towards Al3+ with obvious enhancement in fluorescence emission intensity at 580 nm and remarkable decrease in fluorescence emission intensity at 488 nm, and the fluorescence color also changed from yellow to pink. Furthermore, the detection limit of the probe L, LZn towards Zn2+, Al3+ were 1.25 × 10−7 M and 3.179 × 10−6 M, respectively. Additionally, the complexation properties of L towards Zn2+ and LZn towards Al3+ were studied in detail.

Effects of calcination temperature on the UV light emission of CaO-decorated ZnO nanorods

There have been numerous efforts to cap or decorate ZnO one-dimensional (1D) nanostructures with various materials including metal oxide semiconductors, metals, and polymers, to obtain intense ultraviolet (UV) emission. The UV emission intensity depends strongly on the calcination temperature conducted after the decoration of ZnO 1D nanostructures with other oxide, but it has hardly been reported yet. In this paper, we report on optimal calcination temperature for the most intense UV emission from CaO-decorated ZnO nanorods. The optimal calcination temperature was found to be 400 °C. The intensity of the UV emission from CaO-decorated ZnO nanorods was enhanced and the deep-level visible (vis) emission was suppressed completely with calcination at 400 °C in an oxidizing atmosphere. In contrast, higher temperature calcination resulted in a decrease in UV emission intensity. The underlying mechanism for the enhancement of the UV emission and the complete suppression of the vis emission from the CaO-decorated ZnO nanorods by calcination at 400 °C is discussed in detail.

Microstructural (self-assembly) and optical based discrimination of Hg2+, CN− and Hg(CN)2 ion-pair; Hg2+ promoted-ESIPT assisted guanylation of thiourea

A multifunctional self-assembled dual-chemosensor DTS was synthesized and used for optical and microstructural based discrimination of Hg2+, CN− ions and Hg(CN)2 ion-pair. The addition of Hg2+ ions to the CH3CN solution of DTS promotes the ESIPT phenomena (emission peak at 458 nm red shifted to 510 nm; increase in absorption between 400 and 480 nm), followed by cyclization (guanylation) reaction with concomitant desulfurization (decrease of emission intensity at 510 nm and minor increase at 410 nm; increase and decrease in absorbance intensity at 270 and 325 nm, respectively). In contrast, CN− induced deprotonation in DTS results in simultaneous decrease in absorbance at 310 nm and increase in absorbance at 385 nm and 425–475 nm and fluorescence enhancement at λem 452 nm. On the addition of Hg(CN)2 ion pair, DTS shows apparent effect of both Hg2+ and CN− ions. The mechanism of interaction of DTS with Hg2+, CN− and Hg(CN)2 has been established by detailed 1H NMR and ESI–MS studies. DTS in CH3CN shows flake like morphology which undergoes analyte induced self-assembly to form a bunch of nanorods with Hg2+; segregated nanorods with curvy ends with CN− and spherical structures with Hg(CN)2 ion pair.

Histidine-Stabilized Copper Nanoclusters as a Fluorescent Probe for Selective and Sensitive Determination of Vitamin B12

Herein, we report the highly sensitive and selective determination of vitamin B12 (VB12) using histidine-stabilized copper nanoclusters (His-CuNCs) as a fluorescent probe by the spectrofluorometry method. The as-synthesized His-CuNCs were characterized by UV–Vis absorption, steady-state emission, and high-resolution transmission electron microscopy measurements. His-CuNCs exhibited an emission maximum around 443 nm, when excited at 350 nm. The emission intensity of His-CuNCs was significantly quenched by the addition of VB12, hinting that the synthesized probe can be employed for sensing of VB12. Based on the decrease in emission intensity, the concentration of VB12 was determined and the emission intensity of His-CuNCs can be quenched by VB12 via fluorescence resonance energy-transfer mechanism. His-CuNCs showed high selectivity toward the determination of VB12 in the presence of other potentially interfering vitamins, cations, and anions. In addition, the proposed sensing platform displayed a sensitive response to VB12 in the linear range of 4.00–28.00 × 10−6 mol dm−3 with a limit of detection of 3.30 × 10−9 mol dm−3. The proposed sensing system is simple, low cost, selective, and sensitive for the determination of VB12 in biological samples.

Spatial redistribution of photoexcited carriers in InGaN/GaN structures emitting in a wide spectral range

Capabilities of pulsed mode in metalorganic chemical vapor deposition in growing InGaN-based multiple quantum wells (QWs) emitting in a wide spectral range by varying deposition temperatures are tested. Lowering of the temperatures for growing short-period superlattices, which were used as templates, and the active QWs enabled redshifting the photoluminescence peak position to 580 nm. Spatially-resolved photoluminescence spectroscopy using confocal microscope revealed that the structures emitting at the wavelengths longer than ~530 nm have specific features in the profile of potential fluctuations, which are qualitatively different from those observed in the structures emitting in blue region. The transition from the dominance of the potential fluctuations of a small spatial scale to the prevalence of large-scale potential fluctuations is accompanied by the considerable decrease in emission intensity.

Aggregation induced emission based “turn-off” fluorescent chemosensor for selective and swift sensing of mercury (II) ions in water

An Anthracene based fluorescent probe, 1-(Anthracen-2-yliminomethyl)-napthalen-2-ol (AIN), was synthesized via simple one-pot reaction from inexpensive reagents. Intriguingly, it exhibited novel AIE characteristics in H2O-THF mixtures at high water content. Size and growth process of particles in different volume percentage of water and THF mixtures were investigated using TRPL, DLS, SEM and optical microscope. The fluorescent aggregates exhibited distinct Hg2+-selective “on-off” type fluorescence switching upon binding. Additionally, the fluorescence quenching showed a linear correlation in the Hg2+ concentration range from 0.3 to 3.6 μM and the limit of detection was estimated as low as ∼3 ppb. The drastic decrease in emission intensity of AIN aggregates was observed in the presence of mercury ions via a complex interplay through the ground state complexation between AIN and Hg2+ ions and external heavy atom induced perturbation by Hg2+ ions to the excited states of the AIN. A large Stern–Volmer quenching constant was estimated to be 2.54 × 105 M−1. The proposed analytical system with clear AIE characteristics demonstrates a potential outlook for the on-site visual detection of Hg2+ in paper strips. Finally, the sensory probe was also applied to determine the concentration of Hg2+ in real water samples to demonstrate its practical applications.

1,8-Naphthalimide derived dual-functioning fluorescent probe for “turn-off” and ratiometric detection of Cu2+ based on two distinct mechanisms in different concentration ranges

In this study, a novel 1,8-naphthalimide derived compound bearing the coumarin moiety called 7-Diethylaminocoumarin-3-aceone (N-hydroxyethyl-1’,8’-naphthalimide-4’-) hydrazone (1) has been designed, synthesized and evaluated as a dual-functioning fluorescent probe for “turn-off” and ratiometric detection of Cu2+ based on two distinct mechanisms in different concentration ranges in aqueous solution. This probe 1 showed high selectivity and sensitivity for Cu2+ over other common metal ions, for the limit of detection (LOD) could reach 3.90 × 10−8 M and 3.26 × 10−7 M for “turn-off” and ratiometric detection respectively. Moreover, in Cu2+ equivalence range of 0–0.5, a decrease in fluorescence emission intensity at 441 nm was observed upon addition of Cu2+, but in Cu2+ equivalence range of over 0.5, a new emission band centered at 462 nm appeared with increasing intensity accompanied by a decrease in fluorescence emission intensity at 570 nm, which provided ratiometric fluorescence detection of Cu2+. The sensing mechanisms for the responses of 1 to Cu2+ were chelation-quenched fluorescence (CHQF) and chemical reaction between 1 and Cu2+ over Cu2+ equivalence range of 0–0.5 and more than 0.5, respectively. Thus, this probe 1 could be utilized for sensing and monitoring Cu2+ in environmental and biological systems in different concentration ranges.

Optical Properties of Cubic GaN Quantum Dots Grown by Molecular Beam Epitaxy

We have investigated the optical properties of self‐assembled cubic GaN quantum dots (QDs) in a cubic AlN matrix grown in Stranski–Krastanov growth mode. Two different sample series are fabricated and optically characterized by photoluminescence measurements. Additionally, the experimental results are compared to theoretical calculations. Sample series A consists of one single QD layer with varying GaN amount. A red shift of emission energy of 140 meV is observed with increasing GaN deposition time. Simulations verify this behavior and can be explained by a decrease of the QD height. Sample series B has two layers of QDs on top of each other with different QD deposition amounts of three and six monolayers, respectively. The spacer layer thickness between the QD layers is 2 and 20 nm. A decreased emission intensity of the smaller QDs is measured for QD layers with smaller spacer layer thickness. This observation is a first hint of an electronic coupling between the two QD layers with thin spacer layer thickness resulting in tunneling of carriers from the smaller QDs to the larger QDs. Theoretical calculations further show that a strain induced structural coupling induces a vertical alignment of the QDs.

Influence of in doping in GaN barriers on luminescence properties of InGaN/GaN multiple quantum well LEDs

Room-temperature photoluminescence (RT PL) spectra of InGaN/GaN multiple quantum well (MQW) structures grown by metalorganic chemical vapor deposition (MOCVD) was investigated. It is found that with increasing In content in GaN barriers, the FWHM and emission intensity decreases, and the emission wavelength is first red shift and then blue shift. The shrinkage of FWHM and emission wavelength blue shift can be attributed to the reduction of piezoelectric field, and the lower height of potential barrier will make carrier confinement weaker and ground state level lower, which resulting in emission intensity decreasing and wavelength red shift. In addition, doping the barrier with In will induce more inhomogeneous and deeper localized states in InGaN QWs, which also contribute to a red shift of PL emission wavelength.

Functional evaluation of tryptophans in glycolipid binding and membrane interaction by HET-C2, a fungal glycolipid transfer protein

HET-C2 is a fungal glycolipid transfer protein (GLTP) that uses an evolutionarily-modified GLTP-fold to achieve more focused transfer specificity for simple neutral glycosphingolipids than mammalian GLTPs. Only one of HET-C2's two Trp residues is topologically identical to the three Trp residues of mammalian GLTP. Here, we provide the first assessment of the functional roles of HET-C2 Trp residues in glycolipid binding and membrane interaction. Point mutants HET-C2W208F, HET-C2W208A and HET-C2F149Y all retained >90% activity and 80–90% intrinsic Trp fluorescence intensity; whereas HET-C2F149A transfer activity decreased to ~55% but displayed ~120% intrinsic Trp emission intensity. Thus, neither W208 nor F149 is absolutely essential for activity and most Trp emission intensity (~85–90%) originates from Trp109. This conclusion was supported by HET-C2W109Y/F149Y which displayed ~8% intrinsic Trp intensity and was nearly inactive. Incubation of the HET-C2 mutants with 1-palmitoyl-2-oleoyl-phosphatidylcholine vesicles containing different monoglycosylceramides or presented by lipid ethanol-injection decreased Trp fluorescence intensity and blue-shifted the Trp λmax by differing amounts compared to wtHET-C2. With HET-C2 mutants for Trp208, the emission intensity decreases (~30–40%) and λmax blue-shifts (~12nm) were more dramatic than for wtHET-C2 or F149 mutants and closely resembled human GLTP. When Trp109 was mutated, the glycolipid induced changes in HET-C2 emission intensity and λmax blue-shift were nearly nonexistent. Our findings indicate that the HET-C2 Trp λmax blue-shift is diagnostic for glycolipid binding; whereas the emission intensity decrease reflects higher environmental polarity encountered upon nonspecific interaction with phosphocholine headgroups comprising the membrane interface and specific interaction with the hydrated glycolipid sugar.

Nano Gold (Au0) and Au0-Er3+ Containing Plasmonic K2O-ZnO-SiO2 Glass Nanocomposites: Processing and Properties

ABSTRACTIn this paper, nano gold (Au) and nano gold-erbium (Au-Er) co-embedded potassium zinc silicate based monolithic plasmonic glass nanocomposites have been evaluated. These plasmonic glass nanocomposites of Au were prepared by a controlled heat-treatment of the K2O-ZnO-SiO2 glasses obtained by melt-quench technique. Differential scanning calorimeter, dilatometer, ultra violet-visible absorption spectrophotometer, X-ray diffractometer, transmission electron microscope, Fourier transform infrared spectrometer, prism coupler and spectrofluorimeter were used to characterize the glasses and heat-treated glass nanocomposites. A gradual creation of more Au0 nanoparticles with prolongation of heat-treatment time resulted in strong surface plasmon resonance band around 520 nm in the glass nanocomposite samples. Decreased photoluminescence spectral intensities of Er3+ ion around 550 and 1540 nm due to 2H11/2, 4S3/2 → 4I15/2 and 4I13/2 → 4I15/2 emission transitions were observed with increase in heat-treatment time. The decrease in emission intensity was caused due to lower excitation spectral intensity of Er3+ ions and higher absorption intensity of Au0 nanoparticles around 523 nm with increase in heat-treatment time of the samples.

Optically sensing phospholipid induced coil-helix transitions in the phosphoinositide-binding motif of gelsolin.

We present a systematic experimental and computational study of phospholipid induced peptide coil-helix transitions which are relevant in the context of proteins mediating cytoskeletal rearrangement via membrane binding. We developed a sensitive Förster resonance energy transfer (FRET) based assay to address whether coil-helix transitions in phospholipid binding motifs of actin-binding proteins can be induced by physiologically-relevant concentrations (1-20 μM) of phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2) phospholipids. Based on inter-residue distance constraints obtained from Molecular Dynamics (MD) simulations of a 20 residue peptide (Gel 150-169) from the actin-severing protein gelsolin, we synthetized and labeled the peptide with a tryptophan donor and IAEDANS acceptor pair. Upon addition of PI(4,5)P2 micelles and mixed vesicles containing PI(4,5)P2 and phosphatidylcholine to the peptide, we observed a decrease in the tryptophan emission intensity with increasing concentrations of PI(4,5)P2. The IAEDANS emission spectra showed a more complex profile exhibiting a blue shift of the emission peak and non-monotonic changes in the intensity profile with increasing concentrations of PI(4,5)P2. We showed that the IAEDANS acceptor emission response is a result of both intrinsic polarity sensitivity of the acceptor in the vicinity of the membrane surface and fluorescence energy transfer from the donor. Importantly, the fluorescence lifetime of the donor (tryptophan) showed a monotonous decrease with increasing mol% of PI(4,5)P2 from 1.13 ± 0.10 ns in the absence of phospholipids to 0.25 ± 0.03 ns in the presence of 100% PI(4,5)P2 micelles. We also showed a concomitant increase in FRET efficiency with increasing PI(4,5)P2 levels indicating a PI(4,5)P2 concentration dependent coil-helix transition. Our studies demonstrate that membrane PI(4,5)P2 concentrations as low as 2.5-5 μM can trigger helix-coil conformational changes in gelsolin relevant for triggering regulatory processes in the cell.

Sensitive determination of rutin by spectrofluorimetry using carbon dots synthesized from a non-essential amino acid

The present study describes the synthesis of carbon dots (CDs) using a non-essential amino acid, asparagine as a precursor. The HR-TEM image shows that the size of the prepared CDs was 2.9±0.2nm with a spherical morphology. The UV–visible spectrum of CDs exhibits a major band at 307nm along with a shoulder band around 207nm corresponding to n-π* and π-π* transitions, respectively. Further, the CDs show emission maximum at 441nm when excited at 348nm. The synthesized CDs were then exploited for the determination of rutin by spectrofluorimetry based on the decrease in emission intensity at 441nm. It was found that emission intensity of CDs at 441nm was decreased while adding 0.5μM rutin to CDs. On the other hand, addition of other metal ions and anions including 5mM Mg2+, K+, Ca2+, Na+, NO3− and oxalate, 2.5mM Cu2+ and Fe3+ and 3mM glycine, glucose, histidine, proline and cysteine does not affect the emission intensity at 441nm. A good linearity was observed for the emission intensity against 0.5–15μM rutin with a correlation coefficient of 0.997 and the limit of detection was found to be 1×10−7M (61μg/L) (S/N=3). The real sample analysis was done by determining rutin in a pharmaceutical sample.

One‐Photon and Two‐Photon Mitochondrial Fluorescent Probes Based on a Rhodol Chromophore

AbstractA synthesized water‐soluble rhodol derivative bearing a triphenylphosphonium moiety possesses an intense fluorescent light emission spectrum in the yellow range upon using one‐ or two‐photon excitation techniques. The presence of the positively charged triphenylphosphonium functional group gives rise to selective accumulation and labeling active and coupled mitochondria according to mitochondrial membrane potential Δψ. These chemical and spectroscopic properties of the rhodol derivative allow efficient labeling and imaging eukaryotic cell mitochondria with one‐photon excitation at 488 nm and two‐photon excitation at 800 nm. Selective staining of the coupled mitochondria has been confirmed by a decrease of emission intensity after treatment with protonophore, which acts as an inner mitochondrial membrane‐depolarizing agent. A rhodol‐based fluorescent probe possessing an uncharged structure also accumulates in the eukaryotic cells but with much lower selectivity in relation to the mitochondria. The uncharged rhodol molecule is spread more evenly in the cell without specific organelle labeling. In our experimental conditions, rhodol probes exhibit very low phototoxicity as evaluated based on the morphology of endothelial EA.hy 926 cells.

Band gap engineering, enhanced morphology and photoluminescence of un-doped, Ga and/or Al-doped ZnO nanoparticles by reflux precipitation method

In this study, un-doped ZnO, Ga/Al-doped and co-doped ZnO nanoparticles (NPs) at 2mol% Ga doping (GZO), 2mol% Al doping and combined Ga and Al doping concentrations summing up to 2mol% (ranging from 1:1 to 1.9:0.1mol% Ga/Al) were synthesized using the reflux precipitation method. The effects of increasing the mole ratios of Ga in the ZnO host material or reducing Al mol%, on the structural, luminescence and optical properties of impurity-doped ZnO were investigated along with the properties of ZnO NPs. The X-ray diffraction patterns for all samples exhibit highly crystalline NPs with a hexagonal wurtzite structure. The crystallite size and average relative intensity of the diffraction peaks of the samples increased with increasing Ga doping indicating improved crystallinity with an increase in the content of gallium in the ratio. Photoluminescence spectra also displayed an increase in exciton peak emission with increasing Ga doping levels and reached a maximum at a doping concentration of 2.0mol% Ga, as well as a corresponding decrease in the deep level emission intensity, indicative that the best optical quality was obtained at the 2mol% Ga level. It was observed a blue shift in the PL exciton emission peak position and the band edge emission of the reflectance spectra with increasing concentration of Ga in the sample. The optical band gap calculated from the reflectance data also increased with increasing Ga concentration. These GZO NPs with improved crystallinity, minimum lattice stress, and enhanced luminescence intensity and optical properties would be suitable for deposition on a glass substrate to form the seed layer to produce a transparent conducting oxide for a dye- sensitized solar cell based thin films.