Cd-doped ZnO Research Articles

Effect of Cd-doping on optoelectronic properties of ZnO thin films and their application for MAPbI3 photodetector

Abstract The Sol–gel method was used to synthesize Cd-doped ZnO nanoparticles at different doping concentrations. The nanomaterials crystal structure and microstructure were explained by XRD and SEM analysis of the materials. The absorption and transmission spectra were analyzed to explore the optical properties of Cd-doped ZnO thin films. The band gap of nanomaterials decreases from 3.26 to 3.12 eV with the increase of Cd doping concentration in ZnO. The Cd-doped ZnO shows an increasing trend of electrical conductivity and mobility with the increase of Cd concentration in ZnO. The Cd-doped ZnO-based MAPbI3 photodetectors show substantial responsivity in the wavelength range of 365 to 635 nm. The highest responsivity for devices FTO/ Zn1-xCdxO/MAPbI3/Al, having x = 0.05, 0.10 and 0.15, upon 465 nm wavelength (4 mW cm−2) illumination are ∼0.192, 0.272, and 2.1 μA W−1, respectively. The LDR of the x = 0.15 Cd-doped ZnO photodetector is two times higher than the x = 0.05 concentration of Cd doped ZnO photodetectors. Our studies confirm that the Cd-doped ZnO creates band narrowing and may be used for suitable perovskite photodetector.

The effect of the isoelectronic traps on the luminescence properties of Zn1-XCdXO thin films

In this report, Zn1-xCdxO ceramic thin films were deposited by the sol-gel method on an n-type Si (100) substrate. The structure, morphology, and luminescence properties of the thin films were studied. To elucidate the structure and the optical properties of Zn1-xCdxO thin films, our study focuses on the roles of changing the content of the doped Cd and the annealing temperature in Cd-doped ZnO thin films. The Cd doping behavior was investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and photoluminescence (PL). The research concentrates on the effects of doping concentration, annealing temperature, and isoelectronic trapping on the crystallization quality and luminescence properties of the thin films. On the basis of the different electronegativity of the doping elements, Cd substitution for Zn forms isoelectronic traps, which influence the intensity of luminescence and change the luminous peaks. By raising the annealing temperature further, the intensity of each diffraction peak of ZnO is gradually increasing, improving the quantity of Cd entering the ZnO crystal lattice. The PL spectra display that the ZnO thin films only appear in yellow-green emission bands, which appear redshift through the incorporation of Cd. With the increase in Cd doping amount, the yellow light luminous center keeps moving in the low energy direction. When the Cd doping amount reaches 20 %, the luminescence intensity reaches its maximum, which holds great promise for its application in light devices.

Structural and electrical characterization of Cd-doped ZnO thin films produced on p-type Si substrate by SILAR technique

Structural and electrical characterization of Cd-doped ZnO thin films produced on p-type Si substrate by SILAR technique

Electrochemically synthesized Cd doped ZnO nanorods and integrated atomic Cd-S bridged Cd:ZnO/CdS heterostructure photoanode for enhanced visible light responsive water oxidation applications

Cd-doped ZnO and CdS-decorated ZnO:Cd/CdS heterostructure nanorod arrays (NRA) were successfully fabricated and integrated in this study. The severe surface charge recombination and weak visible light responsivity of ZnO are barriers to the PEC application. Herein, electrochemically synthesized Cd doped ZnO nanorod arrays caged with visible light responsive CdS semiconductor catalyst rehabilitated the photoelectrocatalytic characteristics of the photoanode. The chemically modified Cd:ZnO/CdS photoanode shows a notable photocurrent density of 3.6 mA/cm2(at 0.2 V vs Ag/AgCl) and a prominent onset potential that is negatively shifted by 324 mV relative to the pure ZnOphotoelectrode. The 1D CdS cage around ZnO nanorod improves the visible light responsive photo electrochemical performance with low −1.064 V vs Ag/AgCl onset potential, 740 Ohm/cm2 charge transfer resistance and 0.24% of solar to hydrogen conversion efficiency with high built-in potential (515 mV). The realized result caused by the Cd doping and heterostructure of the ZnO:Cd/CdS photoanode with an exceptional nanostructure photoanode could be a pioneering technique for cost-effective applications in the photoelectrochemistry field.

Cd doped ZnO nanorods for efficient room temperature NH3 sensing

We demonstrate room temperature (25 °C) and low temperature (≦100 °C) NH3 gas sensing properties of Cd-doped ZnO nanorods (NRs) synthesized by a low temperature (90 °C) hydrothermal method. Although, the Cd concentration in the growth solution was varied over a large range from 0 to 80 mol %, the maximum estimated Cd doping concentration in ZnO NRs was 0.5 at % (80 mol %). Structural analysis confirmed the successful doping of Cd in ZnO and microstructure investigation revealed the presence of single nanorod and flower like nanorods in the same ensemble whose dimensions reduced with the Cd doping concentration. Photoluminescence and Raman spectra analyses confirmed the increase of defect concentrations in ZnO NRs by Cd doping thereby enhancing the overall gas sensing. In response to NH3, the nanostructure sensors exhibited a gradual increase in the sensitivity with the Cd doping concentration where the 0.5 at % Cd-doped ZnO NRs showed the highest sensitivity with an enhancement of ∼9% (at 60 ppm NH3) as compared to the un-doped ZnO. The sensitivity continued to rise with the increase of temperature from 110% (25 °C), 120% (50 °C), 170% (75 °C) to 243% (100 °C) indicating a gigantic enhancement of ∼133% at 100 °C from 25 °C. The Cd-doped ZnO NRs also revealed superior specificity of detecting NH3 over NO2, and H2S even at room temperature.

Cd-doped ZnO-based electron transport layer for organic-inorganic hybrid perovskite cells: Experimental and numerical study

Organic-inorganic solar cells (PSCs) are considered emergent photovoltaics (PV) technology. For better performance and stability of the PSCs, the selection of the electron transport layer (ETL) is vital. In this study, Cd doped ZnO (CZO) nanoparticles (NPs) are synthesized using the solution process. The optical properties of the CZO NPs were determined experimentally. With Cd doping, the optical bandgap was reduced and the lowest bandgap was obtained for 2% Cd doping. With further increase of Cd doping concentrations, the bandgap was slightly increased. However, the highest values of refractive index were obtained for Cd doping of 1%. The optical parameters were used to simulate the n-i-p (FTO/ETL/MAPbI3/HTL/Au)-structured PSCs using gpvdm solar simulator. The simulated parameters viz. short circuit current density (Jsc), open circuit voltage (Voc), fill factor (FF), and power conversion efficiency (η) of the CZOs-based PSCs were compared with the parameters obtained for ZnO ETL. An efficiency of 26.07% was achieved for PSC with 1% Cd-doped ZnO, which is 9.72% higher than the efficiency of ZnO-based PSC (η ∼ 23.76%). These experimental results proved an opportunity to improve the performance of the PSCs via Cd doping.

Enhanced blue-shift of the optical band gap in Cd-doped ZnO nanoparticles

Nanoparticles of ZnO prepared through an inexpensive chemical route were doped with controlled quantities of Cd in wt%. The samples were found to be polycrystalline in nature which is confirmed by XRD. They also matched with their respective Powder Diffraction Data files. Morphological and compositional studies were conducted using FESEM to confirm the grain size, texture and doping. Frequency dependent impedance spectroscopy demonstrated that the ac conductivity increases with frequency but decreases with increasing cadmium concentration. Analysis on the samples shows that the absorbance does not significantly change with doping which is further established from the bandgap calculations using the reflectance graphs. Contrary to the common observation, the optical band gap of Cd-doped ZnO is blue-shifted from 3.47 to 3.56 eV as the doping weight percentage is increased to 3 %. This can also confirmed in FTIR analysis as signatures of new peaks in doped samples are obtained. From FTIR spectra it has been observed that the vibrational modes of the doped samples are around 473 cm-1and 475 cm−1. It also confirms a new peak which is due to defects created by incorporation of Cd in the host lattice.

Systematic investigation on the electrochemical performance of Cd-doped ZnO as electrode material for energy storage devices

Many researchers have focused on enhancing the performance of energy storage devices to satisfy the growing demand for energy worldwide. This paper is an attempt to tune the capacitive behavior of pristine ZnO through its Cd doping via the simple synthetic method. To examine their electrochemical behavior, samples of modified ZnO with three concentrations of the dopant (Cd) (3, 6, and 9 wt% Cd-doped ZnO) were prepared. The as-prepared products were characterized by spectral as well as analytical techniques. The 9 wt% Cd-doped ZnO electrode, featuring fast electrolyte permeation and rich electrochemically active sites, showed an excellent specific capacitance (Csp) of 627 Fg−1 at a current density of 1 Ag-1 and substantial cycling stability of 93.3% even after 5000 GCD cycles. The addition of dopants enhanced electrical conductivity due to effective charge transfer and electron transport. The unique nanorod-like structure was found to be responsible for the exceptional electrochemical properties of the samples. Until now, there were no reports on Cd-doped ZnO nanorods as electrode material for supercapacitors. This work provides a simple and cost-effective method for fabricating a 9 wt% Cd-doped ZnO electrode, which may open up new possibilities for efficient electrodes in next-generation supercapacitors.

Antibacterial activity of Cd-doped ZnO nanoparticles against Gram- positive and GRAM-NEGATIVE bacteria

Antibacterial activity of Cd-doped ZnO nanoparticles against Gram- positive and GRAM-NEGATIVE bacteria

Plasmonic nano-particles mediated energy harvesting in thin-film organic solar cells

A Cd-doped ZnO nano-composite (Cd:ZnO) was synthesized using wet chemistry, and then incorporated into the photo-active layer of a thin film organic solar cell (TFOSC) to assist photon harvesting. The nano-composite (NC) formed different sized nano-structures that are beneficial to optical absorption and charge transport processes in the TFOSC. The effects on the NC were studied using a solar absorber medium composed of a poly(3-hexylthiophene) (P3HT) and 6-6-phenyl-C61-butyric acid methyl ester (PCBM) blend with standard device architecture: ITO/PEDOT:PSS/P3HT:PCBM/LiF/Al. The electrical and optical properties of the photoactive films were investigated at various doping levels of Cd:ZnO NC in the medium. The composite showed interesting local surface plasmon resonance, which significantly impacted on the performance of the cells. Consequently, the power conversion efficiency of the TFOSC grew by 84% compared to the reference cell. It is also noted that Cd:ZnO is environmentally stable and compatible for solution device processing.

Room temperature dielectric and optical studies of Cd-doped ZnO nanostructures

Room temperature dielectric and optical studies of Cd-doped ZnO nanostructures

Structural, optical and magnetic properties of Cd doped ZnO nanomaterials for optoelectronic device application

Cd-doped ZnO nanopowder is synthesized by solid-state reaction. XRD pattern shows a sharp pinnacle at θ = 36° which corresponds to (101) plane. Cd-doped ZnO powder shows a little aggleromation indicating that each grain is made of semicrystalline nature with little humps. FTIR shows a high intense broad IR band at 4350 cm−1 corresponding to the O–H stretching vibration. Raman studies clearly shows that the relays of two different peaks which are observed at 315 and 531 cm−1. Impedance plots state that the decrement in Z′ with expanding recurrence might be because of the increment of the AC conductivity. Dielectric behaviour occurs due to the large formation of grains associated with host lattice. Photosensitivity is found to be as high as 86% at input power of 120 mW. From the optical studies, the bandgap energy is measured and it is found to be 3.15 eV. Photoluminescence studies reveal that the sharp peak tends to move so wide as luminescent range changes from red to blue. The peak which has been seen at 631 nm indicates the green. EPR range demonstrates that Cd particles are in mutilated octahedral sties. The magnetic properties lie in the sample with the Cd fixation expands and the molecules can come close to each other and forms the clusters. These results suggest that these materials can be used for optoelectronic and luminescent device applications.

Cd-doped ZnO nanoparticles: An experimental and first-principles DFT studies

The sol–gel method was used for Zn1−xCdxO nanoparticles with various concentrations (x = 0.01, 0.02, 0.03, 0.04, 0.05, 0.1, 0.2, and 0.3). This work aimed to compare the estimated stress, strain, and crystallite size of Zn1−xCdxO nanoparticles using the Williamson–Hall method with the help of the least-squares method for various Cd concentrations with the Debye–Scherrer formula whose level of accuracy was found to be sufficiently comprehensive for this study. The linear regression model was also analyzed statistically and it was shown that our model was very good for 5% of Cd, where the p-values were 0.0018, 0.0202, and 0.0061 for the UDM, USDM, and UDEDM, respectively. According to the density functional theory (DFT) calculations within GGA and GGA+U based on experimental structural data deducing that high band-gap tuned via CBM instead of VB states and increasing Cd amount let band-gap lowered. A redshift was observed according to absorption spectra of the visible region which is more obvious by increasing Cd amount. In addition, one can conclude that band-gap is decreased when crystalline size is reduced through increasing guest concentration. The X-ray diffraction method was used for the structural analysis of all nanoparticles. Up to x < 0.02, Cd replaced Zn and yielded ZnO single phase; while for x ≥ 0.02, two phases (ZnO and CdO) emerged. To determine surface morphology, particle size, and shapes of the nanoparticles, the SEM technique was employed and the EDS was utilized for the elemental compositions of the nanoparticles. It was observed that the ZnCdO nanoparticles had a hexagonal wurtzite structure. Moreover, the crystallite size, microstrain, and stress values became maximum for the Zn0.95Cd0.05O sample.

The controlled synthesis of g-C3N4/Cd-doped ZnO nanocomposites as potential photocatalysts for the disinfection and degradation of organic pollutants under visible light irradiation.

The in situ growth of well-dispersed Cd-doped ZnO nanoparticles (Cd-ZnO NPs) on graphitic carbon nitride (g-C3N4) nanosheets was successfully achieved through the co-precipitation method for the formation of Cd-doped ZnO nanocomposites with g-C3N4 (Cd-ZnO/g-C3N4 NCs). The effect of different compositions of ternary nanocomposites (Cd-ZnO/g-C3N4 NCs) on photocatalytic properties was investigated. Ternary NCs, in which 60% g-C3N4 hybridized with 7% Cd-doped ZnO (g-C3N4/Cd-ZnO) NCs were proven to be optimum visible-light-driven (VLD) photocatalysts for the degradation of methylene blue (MB) dye. The enhanced photodegradation of MB is mainly due to the increase in the generation of photogenerated charge carriers (reactive oxygen species (ROS), O2−, and ˙OH radicals). The electron spin resonance (ESR) experiment revealed that the superoxide and hydroxyl radicals were the leading species responsible for the degradation of MB. Moreover, the NC exhibited tremendous stability with a consistently high MB degradation rate for 10 successive catalytic cycles. The structural and optical properties of CdO, ZnO NPs, Cd-ZnO NPs, g-C3N4 NSs, and g-C3N4/Cd-ZnO NCs were investigated via XRD, SEM, EDX, TEM, FTIR spectroscopy, UV-Vis spectroscopy, ESR spectroscopy, and PL spectroscopy techniques. The synthesized photocatalysts were also applied against Gram-positive and Gram-negative bacterial strains to evaluate their antibacterial activities.

Study the photovoltaic performance of pure and Cd-doped ZnO nanoparticles prepared by reflux method

Abstract In the present work, cadmium doped zinc oxide (Cd-ZnO) nanocrystals have been prepared by the reflux method. The effect of Cd doping on the structural, morphological, optical and photovoltaic properties has been investigated. Structural characterization by X-ray diffraction reveals that polycrystalline nature increases with increasing cadmium incorporation. The particle size shows an increasing trend with increasing cadmium impurification. The average particle size for pure ZnO is 32·19 nm and it augments to 57.94 nm for 10% Cd:ZnO. The strong preferred c-axis orientation is found due to cadmium doping and degree of polycrystallinity of the crystallites also increases with increasing Cd incorporation. Integration of cadmium was confirmed from elemental analysis using EDX. SEM technique proved that the successfully coated the surfaces of the nanostructures. The optical bandgap of the films decreases with increasing Cd dopant. The value of fundamental absorption edge is 3·24 eV for pure ZnO and it decreases to 3·18 eV for 10% Cd:ZnO. The photovoltaic performance was simultaneously enhanced with Cd doing significantly. The results showed that the described synthetic method is appropriate for the preparation of doped nanostructures with high photovoltaic results.

Improved structural and dielectric properties of Cd and Ti dual doped ZnO nanoparticles

This report addressed the impact of Cadmium (Cd) and Titanium (Ti) substitution on the structural, optical and dielectric properties of Zn0.94Cd0.06−xTixO (x = 0 and 0.03). Both the samples are synthesized using the sol–gel auto combustion method and their properties are investigated using X-ray diffraction (XRD), Raman spectroscopy, UV–Visible spectroscopy and dielectric measurements. The structural study using Rietveld refinement of XRD patterns showed the presence of a single-phase hexagonal structure with the P63mc space group for both the samples. The refinement results revealed that with the increase in Ti content, both the lattice parameter and the unit cell volume increase. Shifting of the absorption edge to lower wavelength and blue shift of the bandgap are observed in the UV–Visible spectra of the Ti-doped Zn0.94Cd0.06O sample. The dielectric properties of the prepared samples were investigated by the dielectric spectrometer with varying frequencies. It has been found that dielectric constant and conductivity properties of Zn0.94Cd0.06O are enhanced via Ti substitution.

Solution-processible Cd-doped ZnO nanoparticles as an electron transport layer to achieve high performance polymer solar cells through improve conductivity and light transmittance

In this work, electron transport layers (ETLs) with high charge transfer ability were prepared by doping ZnO nanoparticles with different concentrations of cadmium(Cd). The inverted polymer solar cell based on PTB7-Th: PC71BM as active layer and various concentrations Cd-doped ZnO (CZO) as ETLs were fabricated. The PCE of the device with optimized Cd content in the ZnO film was about 14.7% larger than that of the pure ZnO-based cells. The cadmium-doped ZnO(CZO) is a good candidate to be used as a high-quality transparent electrode in solar cell applications.

Photocatalysis of Cd-doped ZnO synthesized with precipitation method

ZnO particles doped with 0 mol%–5 mol% Cd dopant were successfully synthesized by a precipitation method. The as-synthesized products were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), photoluminescence (PL) spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM) coupled with an energy-dispersive X-ray (EDX) spectroscopy and transmission electron microscopy (TEM). The precursors showed weight loss at 35–700 °C caused by phase transformation and evaporation processes. The as-synthesized products were specified as hexagonal wurtzite ZnO. The crystallite size of ZnO samples doped with 0 mol%–5 mol% Cd gradually increased with the increase in Cd content. The photocatalytic activities of 0 mol%–5 mol% Cd-doped ZnO samples were evaluated through photodecolorization of methylene blue (MB) under ultraviolet (UV) radiation. In this research, ZnO doped with 3 mol% Cd shows the best photocatalytic activity in degrading of MB molecules as much as 89% within 240 min.

Hydrothermally synthesized Cd-doped ZnO nanostructures with efficient sunlight-driven photocatalytic and antibacterial activity

The doping in the metal oxide is key factors that can affect the photocatalytic and antibacterial activity. In present work, Cd-doped ZnO nanostructures have been synthesized by using a facile hydrothermal method. The sunlight induced photocatalytic activity of Cd-doped ZnO nanostructures was evaluated towards the degradation of methylene blue dye. The antibacterial activity of ZnO nanoparticles against Staphylococcus aureus was investigated. The XRD patterns exhibit a wurtzite hexagonal crystal structure with crystallite size in the range of 18–23 nm. Field emission scanning electron microscopy revealed the plate-like morphology of undoped ZnO and it transforms into small nanorods and aggregated irregularly shaped nanoparticles with the incorporation of Cd into ZnO. Energy dispersive spectroscopy analysis confirms the presence of cadmium in Cd-doped ZnO sample. The UV–Visible absorption spectra showed a redshift with an increase in Cd dopant concentration in ZnO. The PL spectra show near band edge emission and defect-related visible emission band. The Cd-doped ZnO exhibits excellent photocatalytic degradation of methylene blue dye compared to undoped ZnO within 30 min. The Cd-doped ZnO (4 wt%) shows maximum photocatalytic degradation efficiency of 84% under sunlight irradiation.

CO Gas Sensor Based on E-Beam Evaporated ZnO, MgZnO, and CdZnO Thin Films: A Comparative Study

This paper reports a comparative study of electron-beam evaporated ZnO, MgZnO, and CdZnO thin film based-gas sensor. At room temperature (RT), these semi-conductive thin films were deposited on Si/SiO2 substrate and an interdigitated pattern of chromium electrode deposited on these films. Device properties, such as structural, optical, and electrical, have been reported and analyzed. The sensors have been tested at different operating temperatures. At 250 °C, the sensor shows the best response for CdZnO thin films. We have obtained sensor response 4.86 with response time 15 sec for 100-PPM carbon mono oxide (CO) gas concentration for CdZnO thin film. Based on experimental results, Cd-doped ZnO has been found most suitable among these semiconducting metal oxides, when used as a CO gas sensor. A correlation between structural, optical, and electrical properties with these thin films has also been established.