Increment In Band Gap Research Articles

Visible-light-operative photocatalyst based on Er-TiO2 Nanostructures Blended with Room temperature ferromagnetism, band-gap Increment, and high optical transparency

TiO2 thin films doped with Er+3 percentage (1-5wt.%) have been prepared using the sol-gel dip coating technique. Er influences the morphological, structural, magnetic, electrochemical, UV, dielectric, Photoluminescence, and photocatalytic properties of TiO2. FTIR was utilized to examine the different functional groups. The confirmation of the anatase phase formation was established through XRD spectra and FTIR spectra. When the concentration of dopant increased, the crystallite size was found to be decreased from 7.96 to 5.62 nm. A blue shift was noticed in transmission spectra as the dopant concentration increased leading to an increase in the bandgap of thin films. The dielectric properties of all thin films exhibited typical behavior. The barrier height, density of localized states at fermi levels, and hopping distance were examined using AC conductivity measurements. As dopant concentrations increased the dielectric constant increased while AC conductivity decreased. The outcomes of electrochemical charge-discharge tests provided the specific capacitance, power density, and Energy of Er-doped TiO2. Er-doped TiO2 especially at 5wt.% showed significant photocatalytic activity in decomposing indigo carmine under sunlight, suggesting its potential for water treatment, and mitigating environmental pollution. Furthermore, Er-doped TiO2 demonstrated efficient functionality as a CO gas sensor. Er-doped TiO2 exhibited violet photoluminescence, with emission intensity modulated by elevating the Er percentage attributed to heightened defect concentration. These properties find a utility in Optoelectronic device applications. Magnetic analysis indicated that incorporating a trivalent dopant (Er+3) into the Ti-O lattice enhanced ferromagnetic properties.

Nano structural and opto-magnetic investigation of Co–Ni co-doped ZnSe for spintronics

Cobalt and Nickel co-doped ZnSe nanoparticles with fixed concentration of nickel and varying concentration of cobalt formulated as Zn0.95-xCoxNi0.05Se(where x = 0.0, 0.01, 0.03, 0.05) are synthesized by using wet-chemical route by co-precipitation method at 60 °C and calcined at 200 °C temperature. The structural study is carried out by applying X-ray diffractometer (XRD) characterization technique and found the synthesized material having crystallite size in nanometer range 08–37 nm with cubic zinc blende structure. Size increment of nanoparticles has been obtained as the concentration of cobalt was increased. Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray Diffractometer (EDX) and Transmission-Electron Microscopy (TEM) analysis of the nanoparticles are performed to study morphology and confirming presence of doped elements by forming Cobalt and Nickel co-doped ZnSe nanoparticles. Fourier-Transform Infrared (FTIR) study is carried out to detect presence of different functional groups, bending and stretching in molecules. Energy band gap is also calculated using UV–Visible spectroscopy and found increment in band gap due to quantum confinement effect. Ferromagnetism is recorded in these Co and Ni co-doped ZnSe nanoparticles using Vibrating-Sample Magnetometer (VSM) characterization technique at 300 K and 15 K.This inducted magnetism is due to the presence of exchange interactions between electrons of different elements. Electron spin resonance (ESR) spectra is also recorded at room temperature by the presence of paramagnetic defects in the samples.

Preparation and investigation of physiochemical, magnetic, and anti-microbial properties of cobalt-doped Bi2S3 nanostructure

The current study proposes the synthesis of cobalt-doped Bi2S3 nanostructures by the unique reverse micelle method at room temperature. Analysis using Energy dispersive analysis of X-rays (EDAX) demonstrated the correct stoichiometry, powder X-ray diffraction (PXRD) data were Rietveld refined using GSAS-II software confirming the formation of orthorhombic Bi2S3 with some residuals for cubic CoS2 phase. As the weight% of cobalt increases, the unit cell volume of orthorhombic Bi2S3 increases from 503.17 (16) (A0)3 to 507.34 (4) (A0)3. The Raman measurement shows the vibrational mode of both orthorhombic Bi2S3 and cubic CoS2 phases. The weak peak centered at 255 cm−1 is due to the symmetric vibration of the Bi–S bond which disappears in cobalt-doped samples and was replaced by new peaks related to Co–S bond vibration. This indicates the deformation in host orthorhombic Bi2S3 crystal due to cobalt doping and is consistent with Rietveld refinement results of PXRD. This work also gives the value of isobaric Gruneisen parameter for CoxBi2-xS3 (x = 0.0,1.0,1.5 & 2.0 wt%) were 5.1, −7.3, −4.8, and −5.2 respectively obtained from the low-temperature Raman measurement. The optical study shows the increment in band-gap with doping and proves to have visible light active band-gap. The pristine Bi2S3 nanostructures showed broad emission from the violet region (400 nm) to the yellow region (590 nm) with maximum emission at 440 nm in the blue region. The PL intensity decreases as cobalt weight% increases because of electron-hole recombination. The morphological study through high-resolution transmission electron microscopy (HR-TEM) revealed the single crystalline nature and showed the change in morphology from nanocylinders and nanorods with nanoparticles. The room temperature ferromagnetic behavior increases as cobalt weight% increases and reaches the maximum for 1.5 wt% cobalt. This study showed that the prepared nanostructures have potential application as an antimicrobial agent against both Gram + ve and Gram-ve microorganisms.

Ab Initio Computational Details With Facile High-Temperature Synthesis of Pure and Alloyed CsPbI3 With Inherent Stability Analysis for Optoelectronic Applications

In this article, wee have performed a density functional theory-based computational experiment to gain insight into stability issues in host CsPbI <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> and attempted doping Mn as a dopant element to stabilize its phase. The obtained results throw light on various useful parameters like lattice structure, electronic band, absorption coefficient, and photoluminescence (PL). The optimized lattice parameter values of parent CsPbI <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> quantum dots (QDs) show a diminution in its value after introducing Mn on the Pb site in the crystal structure from 6.28 to 6.15 Å. This result is following the values of the lattice parameter obtained from experimentally observed X-ray diffraction (XRD) plot (6.25 to 6.15 Å) and high-resolution transmission electron microscopy (6.29 to 6.13 Å). Incorporation of Mn in parent CsPbI <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> QDs leads to phase stability, which can be seen in XRD, PL, and absorption spectra. The PL intensities can be preserved up to 30% and 80% in the case of host and Mn-alloyed CsPbI <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> QDs, respectively. The phase of host CsPbI <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> can be preserved up to five days, while the phase of Mn-alloyed CsPbI <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> QDs can be maintained up to 28 days, which can be seen in XRD plots. In addition, an increment in bandgap from 1.426 to 1.513 eV can be observed after Mn performing alloying in CsPbI <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> QDs from the theoretically calculated band structure plot, which can be further validated with the obtained bandgap values from the Tauc plot (1.76 to 1.81 eV) extracted using UV-visible spectrum.

An effect of metal ions (Cu, Mn) doping on the structural, morphological, optical, photoluminescence, electrical and photocatalytic properties of In2S3 nanoparticles

Pristine and Cu, Mn-doped In2S3 nanoparticles (NPs) were synthesized via a simple, elegant co-precipitation route. The dopant (Cu, Mn metal) influence on the structural, optical, photoluminescence and electrical properties were investigated. The (Cu, Mn) dope In2S3 exhibited polycrystalline XRD phases having particle sizes varying from 36.2 to 49 nm. We noted a substantial decrease in the crystallite size on dopant (Cu, Mn) incorporation in In2S3. From FE-SEM images, nanosheets, nanowires, and needle-like structures were observed. EDS elemental detection confirmed that In, Cu, Mn, and S elements are present in the produced NPs. The increment in bandgap (2.8–3.28 eV) was observed after the Cu, Mn doping in In2S3. Photoluminescence studies demonstrate the photoemission is mainly owing to the donor-acceptor pair transitions. The electrical conductivity decreases significantly with doping, and a maximum electrical conductivity of 1.28 × 10−6 (Ω m)−1 was obtained for pure In2S3 NPs. Mn-doped In2S3 exhibits the highest photocatalytic activity (84%) for Methylene blue.

Effect of trisodium citrate on morphological, structural, and optical properties of fluorine-doped ZnO structures

In this work, we present the effect of trisodium citrate (TSC) addition via a hydrothermal method on the morphological, compositional, structural, and optical changes of fluorine-doped zinc oxide (FZO) on silicon substrates. Field emission scanning electron microscopy revealed vertically aligned nanorods for FZO and pebble and block-like microstructures of different sizes upon TSC addition. X-ray diffraction analysis revealed a hexagonal structure for all the samples. Upon addition of TSC, the sample growth along the c-axis was inhibited strongly and the growth along the a-axis was developed. The crystallite size increased from 28.73 nm to 30.38 nm upon addition of TSC. The oxygen deficiency and, the presence of zinc, oxygen, fluorine, and sodium in the studied samples were confirmed by energy-dispersive X-ray analysis and X-ray photoelectron spectroscopy (XPS). Ultraviolet (UV)-visible analysis revealed the optical energy band gap increment from 3.204 eV to 3.241 eV with TSC addition. Photoluminescence (PL) analysis revealed a significant improvement in the intensity ratio of the near band emission to deep level emission from 5.44 to 12.59 upon TSC addition, indicating crystal quality improvement. Both UV–visible and PL analyses showed that the studied samples were blue-shifted upon TSC addition. The different morphologies with promising properties could be employed in different applications, eliminating the complexity and reducing cost in the fabrication of hybrid structures, and nano/microcomposites.

Effect of annealing and hydrogenation on optical and electrical properties of DC sputtered Mg-Ni bilayer thin films

Mg-Ni (150 nm) bilayer thin films were effectively prepared using the magnetron co-sputtering techniqueonto the glass and ITOcoated glass substrates. In order to get homogeneity in the prepared thin film, annealing of the samples was made at 573 K for an one hour in the vacuum. Afterwards films were hydrogenated at 30 psi H2for one hour. The optical, electrical and structural properties of Mg-Ni thin film were studiedusingUV–visspectroscopy, Keithleyelectrometer, Hall Effect measurement and Field emission scanning electron microscopy(FESEM)along with energy dispersive Spectroscopy (EDS).The optical bandgap of as-deposited thin film was found 3.85 eV and after annealing it was decreased to 3.79 eV.Furthermore, bandgap increment has been observed for annealed hydrogenated thin films and it was 3.91 eV.The Hall Effect measurements and I-V characteristics of samples showthe semiconducting nature(n-type) of the filmsand the conductivity increases after annealing and decreases after hydrogenation of the annealed sample.Further, the Hall Effect measurements indicate increment in the Hall mobility of annealed thin films where as it is found to be decreased after hydrogenation of the annealed samples. FE-SEMimagesrepresent uniform deposition of thin film. The composition of elements was recorded through energy dispersive X-ray spectroscopy (EDAX).Accumulation of hydrogen, particularly at the thin film’s interface, blocks the flow of electrons that results in decreased conductivity of thin film after hydrogenation. Therefore, it may be concluded that Mg-NI thin films are suitable for solid state hydrogen storage.

Magnetic, optical and phase transformation properties of Fe and Co doped VO2(A) nanobelts

In this work, the effects of Fe and Co dopants on the optical bandgap and structural, morphological, and magnetic properties of VO2(A) nanobelts with rectangular cross-sections were studied. The optimized hydrothermal method with proper parameters was used to synthesize the samples. The XRD analyses show that the hydrothermal method promotes the formation of VO2(B) rather than the usual VO2(A) and causes the tetragonal-monoclinic transformation in VO2. Furthermore, expanding the VO2 lattice constant by dopants reveals that Fe3+ and Co2+ are successfully substituted into the lattice sites of V4+. Also, obtained results indicate the optical band gap increment with dopants and superparamagnetic behavior of the samples at room temperature.

Impact of Aluminum Oxide Content on the Structural and Optical Properties of ZnO: AlO Thin Films

AlO-doped ZnO nanocrystalline thin films from with nano crystallite size in the range (19-15 nm) were fabricated by pulsed laser deposition technique. The reduction of crystallite size by increasing of doping ratio shift the bandgap to IR region the optical band gap decreases in a consistent manner, from 3.21to 2.1 eV by increasing AlO doping ratio from 0 to 7wt% but then returns to grow up to 3.21 eV by a further increase the doping ratio. The bandgap increment obtained for 9% AlO dopant concentration can be clarified in terms of the Burstein–Moss effect whereas the aluminum donor atom increased the carrier's concentration which in turn shifts the Fermi level and widened the bandgap (blue-shift). The engineering of the bandgap by low concentration of AlO dopant makes ZnO: AlO thin films favorable for the fabrication of optoelectronic devices. The optical constants were calculated and was found to be greatly affected by the increasing the doping ratio.

Static isotropic pressure induced ultra-wide band gap response of NaCaF3 fluoro-perovskite and its repercussions on optical properties: ab initio calculation

ABSTRACT A comprehensive theoretical study to investigate the outcomes of externally applied static isotropic pressure (0–50 GPa) on electronic, optical and structural properties of NaCaF3, using density functional theory based CASTEP code with ultra-soft pseudo-potential USP plane wave and Perdew Burke Ernzerhof exchange–correlation functional of Generalized Gradient Approximation, is reported. The electronic band gap shows the increasing trend 4.773–6.203 eV with increasing external pressure. The increase in band gap is significant up to 20 GPa as compared to higher external pressures. The mystery of increasing band gap is nicely decoded by the total density of states and elemental partial density of states. Optical properties have been calculated to analyse the impact of increment in band gap on them. We observed that the highest peak of energy loss function shows the blue shift which confirms the increment of band gap. At zero photon energy, for 0 GPa, the static refractive index has a value of 1.4456. After applying external pressure, there is a slight increase in which favours the ultrawide band gap behaviour of the ternary compound. The energy points at which the absorption peak is maxima, the refractive index has lowest value.

Synthesis and Characterization of Cu-Incorporated Zinc Tin Zorcinate Thin Film as a Promising Candidate as Absorber Layer in DSSC

This study presents the elaboration and characterization of un-doped and Copper co-doped Zinc-Tin-Zirconiate (3, 6, 9 mol.%). Cux-ZTZr(2-x) nanostructured thin films prepared using sol-gel Copper co-doped Zinc Tin method on a glass substrate and annealed at 500oC for 1hr. The synthesized film samples are characterized by X-ray (XRD), scanning electron microscopy and energy dispersive X-ray (HR-SEM/EDX), Fourier transform infrared spectroscopy (FTIR), and UV–VIS–NIR double beam spectrophotometer. The experimental results demonstrated that all the prepared films exhibited a polycrystalline nanoparticle structure, and the crystallites size was found to be ranged from 17 and 32 nm. SEM micrographs showed scattered nanoparticles with irregular distribution over the substrates, and the particles size is in the range of 21–29 nm. The highly transparent (>85% for doped sample) nanostructures films show a bandgap increment from 4 to 4.19 ev with rising Copper content in zinc Tin Zirconiate. The effect of Cu focus in ZTZr will differ in the optical properties of the semiconductor, which means that these films have many advantages in solar cell application.

Bandgap engineering of hydrogenated a-SiC:H thin films for photoelectrochemical water splitting applications

Bandgap engineering of a-SiC:H thin films was carried out to assess the material light absorption without compromising its photoelectrochemical water splitting capabilities. The tailoring was performed by varying the hydrogen concentration in the semiconductor and by post-deposition isochronical annealing treatments from 100 °C to 700 °C. Bandgap values were obtained by fitting the fundamental absorption region of the absorption coefficient using three different models. Differences among bandgap values extracted by these methods and its correlation with the a-SiC:H structure, demonstrate that structural features, rather than a hydrogen rearrangement or depletion, would be responsible for annealing induced optical bandgap increment. These features are taking in advantage for the bandgap engineering of a-SiC:H without changing Si-C stoichiometry. Optical bandgap values for p-doped a-SiC:H samples gradually increased from 2.59 to 2.76 eV upon performing each annealing step until 600 °C. Temperature at which an enhancement in the electric performance is observed. We believe, these results will help on the design of monolithic tandem solar cells for water splitting applications.

Structural, optical and magnetic behaviour of cobalt- and ferrous-doped zinc stannate nanoparticles synthesized by hydrothermal method

Zinc stannate has attracted substantial interest owing to its unique properties making it a suitable ternary oxide for numerous applications. One of the most promising ternary semiconducting oxides, zinc stannate (Zn2SnO4) is more stable than binary semiconducting oxides such as ZnO and SnO2 because of its attractive physical properties and very high electrical conductivity. Nanoparticles of pure and doped Zn2SnO4 were synthesized via facile hydrothermal technique. Characterization methods such as XRD, FTIR, SEM, UV and VSM were carried out to study the behaviour of zinc stannate. X-ray diffraction analysis confirmed the phase purity and high crystalline nature of the synthesized sample. Scanning electron micrography illustrated its spherical morphology. The increment of bandgap was observed for the doped zinc stannate. The presence of functional groups was confirmed using FTIR spectrum. The magnetic property of the material was analysed using vibrational sample magnetometer and found to exhibit diamagnetic behaviour for pure zinc stannate and weak ferromagnetic property for Co- and Fe-doped Zn2SnO4. The attained results depict the excellent and exceptional structural, optical and magnetic properties which establish the use of Zn2SnO4 nanoparticles in a wide range of applications especially in the field of optoelectronic devices and spintronics.

Optical and electrical properties of Ti1-XSnXO2 nanoparticles

In this work we successfully doped Sn to TiO2 in an anatase and rutile structural form from 0.2% to 1% by standard peptization method. Crystallographic properties and reduction in size is confirmed by XRD, Scherrer formula confirms the average crystallite size from 92 to 40 nm. UV–Visible spectra confirms the increment in band gap and absorption is in visible region from 420 to 435 nm. SEM images show the reduction in the size and tending towards spherical in nature with average particle size from 110 to 40 nm. EDAX confirms the doping is successful as with the desired amount from 0.2% to 1%. Pellet form of these samples were studied in the frequency range from 1 MHz–10 MHz, which shows the ε′ predominant in the lower frequency region, which is more for the particle size of 67 nm at 1 MHz, then it decreases instantly with increase in frequency then saturates with increase in frequency due to charge carriers, with hopping conduction is prominent at this region. ε′′ and tanδ show the same nature loss is minimum in lower frequency and slightly increases with the frequency and then decreases at higher frequencies, and it decreases with decrease in particle size due to size effect. σac Increases with increase in frequency, at 1 MHz σac maximum for average particle size and it decreases with decrease in particle size due to hopping conduction become predominant.

Quantum Capacitance Model for Graphene FET-Based Gas Sensor

Because of its extraordinary characteristics, this material has attracted researchers in various arenas. Among the numerous fields where this material can be applied is the gas sensor technology. The graphene experiences remarkable changes in its electrical and physical characteristics when exposed to different gases; and they are, therefore, the ideal candidates for gas sensing application. However, a deep understanding of the effects of gas molecules on the graphene energy band structure and its electronic properties, need to be further studied. In this paper, a new quantum capacitance model for the gas sensor employing the graphene field effect transistor platform is proposed. Hence, a general approach using the Tight-binding approximation based on the nearest neighbor incorporating Schrodinger equation is developed. Therefore, the adsorption effects of the CO, NO, and NH3 gases on the energy band structure, quantum capacitance, and I-V characteristics of the graphene FET are analytically modeled and investigated. The results indicated that, the gas adsorption can cause significant changes on the graphene band structure and quantum capacitance. The I-V characteristics evaluation indicated current decrement after gas adsorption because of the conductance decrement induced by the band gap increment. The proposed models for the capacitance were also compared with the published experimental data and a satisfactory agreement was achieved.

Sol–gel mediated microwave synthesis of pure, La and Zr doped SnS2 nanoflowers an efficient photocatalyst for the degradation of methylene blue

La and Zr intercalated SnS2 nanostructures have been synthesised using facile sol–gel mediated microwave method. Photocatalytic activity of methylene blue dye was investigated using the synthesized nanosturctures and superior photocatalytic activity was witnessed for the La and Zr intercalated SnS2 than the pure SnS2 nanoflower. It is attributed to the enhanced surface charge carriers and fast electron transport inside the lattice of SnS2. Enlargement on surface active sites in turn increases surface absorption effect due to La and Zr which acts as tentacles to control the recombination process and promotes the higher photoredox reaction. The synthesized nanomaterials were characterized using PXRD, Raman, PL, UV–Vis spectroscopy, FE-SEM and XPS. It is noted from the structural analysis that the decrease in cell volume with increase of doping concentration contributes to Moss-Burstein effect. The increment of band gap and quenching in the photoluminescence effect supported the absorptivity of photoenergies which served as photosensitizer.

Influence of Mo-vacancy concentration on the structural, electronic and optical properties of monolayer MoS2: A first-principles study

Effects of Mo-vacancy concentration on the structural, electronic and optical properties of monolayer MoS2 have been investigated using the first-principles calculations. Results show that Mo-vacancy is prone to form in monolayer MoS2 under S-rich condition. S atoms around Mo-vacancy exhibit an outward relaxation, whereas Mo atoms around Mo-vacancy show an inward relaxation. At low Mo-vacancy concentration, some localized impurity states are induced in the band gap of monolayer MoS2, coupled with a band gap increment. As the Mo-vacancy concentration increases, the impurity states become delocalized and mix with the upper valence bands, resulting in the band gap decrease. The covalent character of Mo-S bonding is enhanced upon the introduction of Mo-vacancy, and the enhancement is weakened as the Mo-vacancy concentration increases. Optical properties calculations show that the static dielectric constant increases with the increasing Mo-vacancy concentration. The imaginary part of complex dielectric function exhibits a little blue shift for monolayer MoS2 with low Mo-vacancy concentration, whereas the imaginary part of complex dielectric function shows distinct red shift for monolayer MoS2 with high Mo-vacancy concentration.

Hybrid density functional study of bandgaps for 27 new proposed half-Heusler semiconductors

Recently, 27 new half-Heusler compounds XYZ (X = Co, Rh, Fe, Ru, Ni; Y = Sc, Ti, V; Z = P, As, Sb, Si, Ge, Sn, Al, Ga, In) with 18 valence electrons are proposed and their bandgaps span a wide range of 0.10–1.39 eV, which have a great potential of applications in varied areas. Note that the bandgaps are predicted on the gradient-corrected Perdew-Burke-Ernzerhof functional, which underestimates the magnitude of bandgap. To obtain the accurate bandgaps, we recalculate them based on the Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional. Our results show that the nonlocal correction from the HSE06 functional mainly acts on the two lowest conduction bands. The variation in energy separation between these two bands dominates the relative increment of bandgap. More importantly, the band ordering is distinguished in the presence of HSE06 functional, where the dz2 orbital exhibits. When the lattice constant varies, such a band ordering can be inverted, similar to the case of topological insulators. In addition, we find an abnormal behavior of the bandgap related to the Pauling electronegativity difference between the X- and Z-sites, which arises from the delocalization of charge on the Y-site. We expect that our work can provide guidance to the study of bandgap based on the hybrid density functional theory in the half-Heusler semiconductors.

Structural Distortion and Bandgap Increment in Nanocrystalline Wurtzite Si Substituted ZnO.

Crystalline Zn(1−x) Si(x) O(0 ≤ x ≤ 0.156) nanoparticles reveal decreasing particle size with increasing Si content and a undistorted wurtzite form until x = 0.062 beyond which local deformation is observed maintaining the parent structure. There is a sharp increment in bandgap with nominal Si-doping and then almost saturates onwards. Moreover thermal annealing demonstrate the increase bandgap and decreasing lattice parameters. The details of samples synthesis and characterization is presented in the present manuscript.

Structural and optoelectronic properties of glucose capped Al and Cu doped ZnO nanostructures

AbstractAl and Cu doped ZnO nanoparticles are considered as appropriate for modulation of structural and optoelectronic properties. Al atoms are found to substitute the host Zn whereas Cu dopants mainly segregate in grain boundaries and thereby determine the optical properties. The undoped as well as Al and Cu doped ZnO exhibit spherical well defined particles. The spherical nanoparticles change to rod type structures on co-doping. The average particle size decreases on doping what consequently results in an increment in band gap. Blue shift in UV absorption is governed by the functional group of glucose; further blue shift occurring on metal doping may be attributed to Burstein-Moss effect. PL spectra of doped and undoped ZnO show a dominant near band gap UV emission along with visible emission owing to the defects. The PL peak intensity increases on doping with Cu and Al. The linear I-V characteristics indicate the ohmic behavior of ZnO nanostructures.