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Laser Reduction of Graphene Oxide/Zinc Oxide Nanoparticle Nanocomposites as a Onea??Step Process for Supercapacitor Fabrication
摘要： Herein, the laser reduction of graphene oxide (GO) and zinc oxide nanoparticle (ZnONP) nanocomposite ?lms is proposed as a one-step process for supercapacitor fabrication. The ?lms, deposited by casting onto a ?exible poly(ethylene terephthalate) (PET) substrate coated with indium-doped tin oxide (ITO), are subjected to laser irradiation (5 mW, 405 nm) to reduce the GO phase and produce laser-reduced GO (LRGO). Scanning electron microscopy/energy dispersion spectroscopy (SEM–EDS), micro-Raman spectroscopy, and current versus voltage (I(cid:1) V) analyses show a partial reduction of GO to LRGO, forming several conductor-insulating (LRGO/GO) microporous interfaces, and thereby favoring the formation of a supercapacitor structure. Moreover, the topmost LRGO ?lm layer is extensively reduced, making it suf?ciently conducting to work as the counter electrode as well. However, the reduction process is less effective when ZnONPs are introduced into the GO matrix because ZnONPs get clustered and scatter the incident laser before reaching the GO phase. The capacitive behavior, assessed by cyclic voltammetry and galvanostatic charge–discharge measurements, reveals the following (cid:3)1 (GO/LRGO/ ZnONP). The method proposed herein is advantageous because it produces the microcapacitor structures and LRGO counter electrode in a single laser reduction step.
关键词： laser-reduced graphene oxide,graphene oxide,nanocomposites,micro-heterojunctions,zinc oxide nanoparticles
更新于2025-09-23 15:21:01
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Highly Stable Red Quantum Dot Light Emitting Diodes with Long T <sub/>95</sub> Operation Lifetime
摘要： Quantum dot light-emitting diodes (QLEDs) with excellent performances such as external quantum efficiency (EQE) and lifetime have almost met the requirement of low brightness display. However, the short operation lifetime under high brightness limits the application of QLEDs in outdoor displays and lightings. Herein, we report a highly efficient, stable red QLED by using of lithium and magnesium co-doped as well as magnesium oxide shell-coated zinc oxide nanoparticle layer as electron transport layer (ETL). The optimized QLED has a high peak EQE of 20.6%, a low efficiency roll-off at high current, and a remarkably long lifetime T95 > 11000 h at 1000 cd m-2, which indicates the realization of the most stable red QLED up to now. The improvement in the long-term stability of the QLED is attributed to the use of co-doped and shell-coated zinc oxide ETL with reduced electron injection to improve the charge balance in device.
关键词： EQE,QLEDs,electron transport layer,ETL,magnesium oxide shell-coated zinc oxide,Quantum dot light-emitting diodes,external quantum efficiency,lithium and magnesium co-doped,ZLMO@MO,lifetime
更新于2025-09-23 15:21:01
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Design of color tunable thin film polymer solar cells for photovoltaics printing
摘要： Color tunable thin film polymer solar cells have demonstrated the potentials of a wide applications in photovoltaics printing, which is significant for ink pollution reduction and energy saving. This work presents a new effective approach to realize color-tuning photovoltaic cells with optical microcavity structures. Aluminum-doped zinc oxide is utilized as electron transport layer material. With its high electrical conductivity, the thickness tuning range can be quite large, which means the cavity length has a wide variation range. It thus provides sufficient space for optical thin film design to obtain multi colors. By the transfer matrix method, device reflection and absorption spectra are numerically investigated. Based on that, the optical principles for color tunability are explored. In further step, the relationship between device photovoltaics performance and reflective colors are also discussed. Finally, the color coordinates and luminosities are calculated. As results, the colors of the devices designed are capable to cover a relatively large region in Commission Internationale de l′Eclairage (CIE) 1931 x, y chromaticity diagram, which is available to be integrated into the advertisement poster boards, building wall printing and other display applications.
关键词： optical microcavity,thin film polymer solar cells,aluminum-doped zinc oxide,photovoltaics printing,color tunable
更新于2025-09-23 15:21:01
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Effects of background gases and pressure in pulsed laser deposition of Al-doped ZnO
摘要： Background gases (O2, He or Ar) with the pressure from ~ 10?3 Pa to 133.3 Pa are used in 355 nm laser deposition of Al-doped ZnO at room temperature. The effects of these gases and pressure on plasma formation are studied by optical emission spectroscopy (OES) and time of flight (TOF) measurement. The OES results show that the emission intensity of the species in O2 and Ar decrease slightly and then increase exponentially above ~ 5 Pa. The emission intensity in Ar is the highest, followed by emission in O2 whilst the emission in He is low and weakly depend on background gas pressure. TOF measurements indicate that the ion velocity decrease with increasing O2 and Ar pressure at about 5–10 Pa. The ion velocity is highest in He while the ion velocities in O2 and Ar are similar. Thin-film samples deposited in different gas at 2.6 Pa are amorphous, but those deposited at 133.3 Pa are crystalline and exhibit different morphologies and optical properties depending on type of gas. Samples deposited in O2 are highly transparent but those deposited in He and Ar contain nano and micron-sized structures with <50% transmittance. In addition, Zn crystallites are detected by X-ray diffraction.
关键词： Pulsed laser deposition,Background gases,Aluminum-doped zinc oxide,Pressure,Laser produced plasma,Nanostructured films
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 11th International Conference on Humanoid, Nanotechnology, Information Technology, Communication and Control, Environment, and Management ( HNICEM ) - Laoag, Philippines (2019.11.29-2019.12.1)] 2019 IEEE 11th International Conference on Humanoid, Nanotechnology, Information Technology, Communication and Control, Environment, and Management ( HNICEM ) - Voltage Characterization of Magnesium-doped Zinc Oxide by Electrodeposition Method for Solar Photovoltaic (PV) Cells
摘要： The research paper adapted the study of Rajpal and Kumar (2016). The Magnesium (Mg)-doped Zinc Oxide (ZnO) was prepared using the electrodeposition method. The samples obtained from the experiment were then collated to observe the photoconductivity value and the percentage of Voltage Regulation of the plates. Three (3) different tilt angle orientation were utilized in gathering the data of the Voltage Regulation percentage (%VR) and photoconductivity. The photoconductivity value acquired from the undoped plate is 0.7083 while, for the doped plates are 0.8438V, 0.6897V and 0.7204V. On the other hand, the %VR acquired for 0?, 13? and 20° were 1.283%, 5.820% and 3.456%, respectively. Moreover, the percent Battery Charge collated from the experiment are 0.39%, -1.20% and 1.11%, respectively. Further, the experiments showed that sun exposure and temperature have a significant impact on the electrical conductivity and output of the cells.
关键词： electrodeposition,tilt angles,Magnesium-doped,zinc oxide
更新于2025-09-23 15:21:01
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Zinc oxide quantum dots for textile dyes and real industrial wastewater treatment: Solar photocatalytic activity, photoluminescence properties and recycling process
摘要： Three samples of ZnO quantum dots (ZQDs) were synthesized by a modified sol–gel method at different temperatures for 3 h. The first sample (S1) was prepared at room temperature 27 °C, while second and third samples (S2) and (S3) were prepared by the calcination process at 500 and 900 °C, respectively. A study of XRD and TEM determines the purity, high crystallinity and the presence of elongated shape of the prepared catalysts. On using TEM, DRS and EBT analysis, the crystallite size values, bandgap energy, and active surface area were (7.1 nm, 3.49 eV, and 150.1 m2/g), (9.8 nm, 3.45 eV and 112.2 m2/g) and (13.5 nm, 3.39 eV and 78.94 m2/g) for S1, S2, and S3, respectively. The Photoluminescence properties showed that the fluorescence rate for S1 was doubled the observed one in the S2 sample. The photodegradation results of both methyl orange as an industrial raw material and real industrial wastewater of S1 sample showed the finest activity when compared with the rest samples. It was cleared from the collecting data that the photocatalytic performance decreases with the crystallite size increases The mineralization efficiency of the real industrial wastewater that exposed to sunlight for six months were evaluated according to the allowed COD limit for Egyptian Environmental Law, In addition the recycling process for reusable for ZnO prepared samples for 8 times investigated and evaluated.
关键词： Real industrial wastewater,Zinc oxide quantum dots,Solar photocatalytic activity,Recycling process,Sol-gel method
更新于2025-09-23 15:21:01
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Suppressing the Photocatalytic Activity of Zinc Oxide Electron-Transport Layer in Nonfullerene Organic Solar Cells with a Pyrene-Bodipy Interlayer
摘要： Organic solar cells based on nonfullerene acceptors have recently witnessed a significant rise in their power conversion efficiency values. However, they still suffer from severe instability issues, especially in an inverted device architecture based on the zinc oxide bottom electron transport layers. In this work, we insert a pyrene-bodipy donor?acceptor dye as a thin interlayer at the photoactive layer/zinc oxide interface to suppress the degradation reaction of the nonfullerene acceptor caused by the photocatalytic activity of zinc oxide. In particular, the pyrene-bodipy-based interlayer inhibits the direct contact between the nonfullerene acceptor and zinc oxide hence preventing the decomposition of the former by zinc oxide under illumination with UV light. As a result, the device photostability was significantly improved. The π?π interaction between the nonfullerene acceptor and the bodipy part of the interlayer facilitates charge transfer from the nonfullerene acceptor toward pyrene, which is followed by intramolecular charge transfer to bodipy part and then to zinc oxide. The bodipy-pyrene modified zinc oxide also increased the degree of crystallization of the photoactive blend and the face-on stacking of the polymer donor molecules within the blend hence contributing to both enhanced charge transport and increased absorption of the incident light. Furthermore, it decreased the surface work function as well as surface energy of the zinc oxide film all impacting in improved power conversion efficiency values of the fabricated cells with champion devices reaching values up to 9.86 and 11.80% for the fullerene and nonfullerene-based devices, respectively.
关键词： bodipy,zinc oxide,photocatalytic activity,pyrene,organic solar cells,photostability,nonfullerene acceptors
更新于2025-09-23 15:21:01
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Electroluminescence from amorphous GIZO/p-GaN heterojunction light-emitting diodes
摘要： The electroluminescence from the amorphous gallium-indium-zinc oxide (a-GIZO)/p-GaN heterojunction light-emitting diodes (LEDs) were demonstrated. The heterojunction LEDs showed a current flow under both forward and reverse bias voltages. The light emissions were observed at around 410 nm (originating from p-GaN) and ~450–800 nm (originating from interfacial layer and/or from a-GIZO), which were particularly pronounced under reverse bias condition. As a result, the standard white light with the chromaticity coordinate of (0.2899, 0.3034) was obtained.
关键词： Light emitting diode,Gallium-indium-zinc oxide,Heterojunction,Amorphous
更新于2025-09-23 15:21:01
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A low-temperature limit for growth of ZnO nanowires by using of laser ablation processes
摘要： The contribution deals with growth of ZnO nanowires on metal catalysts by using of pulsed laser deposition and with the influence of growth temperature. The process of nanowires preparation comprised two technological steps—both were based on pulsed laser ablation processes: (1) production of metal nanoparticles by laser ablation in liquids and (2) pulsed laser deposition of ZnO nanowires by ablation of ZnO target on substrate with metal nanoparticles. Nanoparticles from various metals (Au, Ag, Ni, Cu, Al, Mg, Zn, Sn and BiSn alloy) were prepared by pulsed laser ablation at 1064 nm in deionised water. Colloids contained metal nanoparticles were applied on Si (100) substrates, and after drying, nanoparticles served as catalysts of VLS crystallisation. Temperatures in interval 600—200 °C were experimentally compared for the nanowires growth with applied ablation laser working at 248 nm. The lowest achieved temperature value for growth of ZnO nanowires was 425–450 °C. However, among applied metals Cu and Al nanoparticles only successfully catalysed ZnO nanowires at this temperature. Properties of prepared samples were investigated by scanning electron microscopy and photoluminescence. Experimental results revealed that along with the growth temperature, selection of proper metal catalyst is also important factor for nanowires crystallisation.
关键词： Nanoparticles,Zinc oxide,Pulsed laser ablation,Nanowires,Directed growth
更新于2025-09-23 15:21:01
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ZnO Nanosheets Modified with Graphene Quantum Dots and SnO2 Quantum Nanoparticles for Room-Temperature H2S Sensing
摘要： Overcoming the low selectivity issue of semiconductor oxide (SMO)-based gas sensors at room temperature and realizing the accurate detection of trace disease biomarkers are highly desirable for widespread deployments of sensors in exhaled breath. Here, a self-assembly strategy is proposed to create a graphene quantum dot (GQD) functionalized porous and hierarchical SnO2 quantum nanoparticles (SnO2QNP)/ZnO nanostructure. SnO2QNP/ZnO nanosheets self-assembled directly on the digital integrated electrodes with a post-synthetic humidity treatment (psHT), the construction of GQD and SnO2QNP loaded ZnO nanosheet heterostructure is highly controllable and reproducible. The strong synergistic effect and p-n heterojunction between the p-type GQD and n-type SnO2 and ZnO effectively enlarged the resistance variation due to the change in oxygen adsorption. In comparison with pristine ZnO and SnO2/ZnO sensors, the GQD modified hierarchical SnO2QNP/ZnO nanostructure exhibited a remarkably high response (S=15.9 for 0.1 ppm H2S) and rapid response/recovery time (14/13s), and good selectivity towards H2S against other interfering gases. In particular, we applied principal component analysis (PCA) to analyze the sensing performance of GQD-SnO2QNP/ZnO sensor and found that the combined effects of GQD/SnO2QNP/ZnO heterointerfaces contributed to the improvement of selectivity of sensors. The results demonstrate that the GQD modified SMO with the hierarchical structure has a high potential in the non-invasive exhaled diagnosis.
关键词： graphene quantum dot,principal component analysis,exhaled diagnosis,gas sensor,zinc oxide nanosheet,tin dioxide quantum nanoparticle
更新于2025-09-23 15:21:01