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The CsPbX 3 perovskites have demonstrated promising applications in the field of X-ray detection. Appropriate element doping to substitute Pb in CsPbX 3 not only improves the photoresponse performance of the resulting material but also reduces the Pb content for achieving environmental protection. Herein, X-ray detectors based on Sr-doped CsPb 1-x Sr x Br 3 thick films were developed. The effects of Sr doping concentration were investigated. The incorporation of Sr increased the density of the CsPbBr 3 thick film and modulated the bandgap of the materials. CsPb 1-x Sr x Br 3 exhibited good optical responses at different bias voltages and X-ray doses. The X-ray response improved as the Sr-doping concentration increased. Therefore, the partial substitution of Sr into CsPbBr 3 is suitable for reducing the Pb content in X-ray detectors. Furthermore, the development of CsPb 1-x Sr x Br 3 thick films provides a new strategy for the detection of X-rays. [ABSTRACT FROM AUTHOR]

The nitrogen-doped TiO2 thin films are deposited on the glass substrate by using a direct-current (DC) magnetron sputtering technique. The film properties are analyzed by X-ray diffraction (XRD), atomic force microscopy (AFM), UV-vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) measurements. The results show that, under the same working pressure and other conditions, nitrogen doping promotes the phase transition from anatase to rutile. Also, on changing the nitrogen–oxygen ratio, nitrogen atoms enter the TiO2 lattice in different positions. When oxygen is abundant, nitrogen atoms will be presented in the interstitial positions; when oxygen is insufficient, nitrogen atoms enter the oxygen vacancies first, forming a substituted position. Finally, we find that, with the increase in nitrogen–oxygen ratio, the sample has a better response to visible light, attributed to the change in the energy band-gap. [ABSTRACT FROM AUTHOR]

In this paper, the dye-sensitized solar cells (DSSCs) were fabricated based on natural dyes extracting from carrot, mulberry, purple cabbage, potato, and grapes. The ultraviolet-visible spectra suggested purple cabbage and mulberry possess better absorption at 300–550 nm. The solar cells using purple cabbage as dye achieved a conversion efficiency of 0.162% with short-circuit photocurrent density ( J sc ) of 0.621 mA/cm 2 , open circuit voltage ( V oc ) of 0.541 V and fill factor ( FF ) of 0.484. The Infrared spectra revealed the bond of O H, C C, C O, C H were existed in purple cabbage. Finally, the optimal extraction time of dyes is also presented. [ABSTRACT FROM AUTHOR]

All-inorganic CsPbI2Br inverted perovskite solar cells (PSCs) have drawn increasing attention because of their outstanding thermal stability and compatible process with tandem cells. However, relatively low open circuit voltage (Voc) has lagged their progress far behind theoretical limits. Herein, we introduce phenylmethylammonium iodide and 4-trifluoromethyl phenylmethylammonium iodide (CFPMAI) on the surface of a CsPbI2Br perovskite film and investigate their passivation effects. It is found that CFPMAI with a –CF3 substituent significantly decreases the trap density of the perovskite film by forming interactions with the under-coordinated Pb2+ ions and effectively suppresses the non-radiative recombination in the resulting PSC. In addition, CFPMAI surface passivation facilitates the optimization of energy-level alignment at the CsPbI2Br perovskite/[6,6]-phenyl C61 butyric acid methyl ester interface, resulting in improved charge extraction from the perovskite to the charge transport layer. Consequently, the optimized inverted CsPbI2Br device exhibits a markedly improved champion efficiency of 14.43% with a Voc of 1.12 V, a Jsc of 16.31 mA/cm2, and a fill factor of 79.02%, compared to the 10.92% (Voc of 0.95 V) efficiency of the control device. This study confirms the importance of substituent groups on surface passivation molecules for effective passivation of defects and optimization of energy levels, particularly for Voc improvement. [ABSTRACT FROM AUTHOR]

The all-inorganic perovskite cesium lead bromine (CsPbBr3) has attracted much attention in the field of X-ray detectors because of its high X-ray absorption coefficient, high carrier collection efficiency, and easy solution preparation. The low-cost anti-solvent method is the main method to prepare CsPbBr3; during this process, solvent volatilization will bring a large number of holes to the film, leading to the increase of defects. Based on the heteroatomic doping strategy, we propose that Pb2+ should be partially replaced by Sr2+ to prepare leadless all-inorganic perovskite. The introduction of Sr2+ promoted the ordered growth of CsPbBr3 in the vertical direction, increased the density and uniformity of the thick film, and achieved the goal of CsPbBr3 thick film repairing. In addition, the prepared CsPbBr3 and CsPbBr3:Sr X-ray detectors were self-powered without external bias, maintaining a stable response during on and off states at different X-ray dose rates. Furthermore, the detector base on 160 µm CsPbBr3:Sr had a sensitivity of 517.02 µC Gyair−1 cm−3 at zero bias under the dose rate of 0.955 µGy ms−1 and it obtained a fast response speed of 0.053–0.148 s. Our work provides a new opportunity to produce cost-effective and highly efficient self-powered perovskite X-ray detectors in a sustainable way. [ABSTRACT FROM AUTHOR]

In this paper, we have achieved the hollow shell ZnS QDs with a simple preparation process, and deeply analysed the mechanism of hollow shell ZnS QDs (~10 nm). The co-doping of copper (Cu) and manganese (Mn) caused the cooperated effects on the ZnS quantum dots, in which hollow shell structure can be formed. The mechanism is that Mn2+ ions in ZnS matrix provide some diffusion channels allowing the outward movement of the Cu2+ ions. In addition, it has been shown that Cu doping at 0.2–0.3% and Mn doping at 3% could form hollow shell structure. [ABSTRACT FROM AUTHOR]

The unmanned aerial vehicle (UAV) is considered a promising auxiliary relay for enhancing network coverage due to its easy deployment, agility, and maneuverability. In order to overcome the obstruction of towering buildings and the limitation of relaying energy, this paper proposes a half-duplex decode-and-forward UAV-assisted relaying network based on simultaneous wireless information and power transfer scheme. The power splitting (PS) is implemented at the UAV relay to address the challenge of energy limitation by separating information and energy from the radio frequency signal. We also study the impact of hardware impairments on transmitters, which can actually degrade communication performance. We derive both an exact expression and asymptotic analysis for the outage probability (OP) with energy harvesting and hardware impairments. In addition, we formulate an optimization form to find the optimal PS ratio and minimize the outage probability. Due to the nonconvex nature of this optimization problem, we perform a series of transformations to reformulate it into a convex optimization form. Experimental simulations validate our theoretical results. Specifically, optimal altitude for UAV is about 300 m and relatively constant in different conditions. The OP of our work is nearly 0.33 smaller than that of AF relaying in a given situation. Moreover, we provide practical guidance for the design and deployment of the UAV-assisted communication by exploring the effects of UAV's altitude, hardware impairments level, and power splitting ratio on the outage probability. [ABSTRACT FROM AUTHOR]

The advancement of efficient and stable inverted CsPbI 2 Br perovskite solar cells (PSCs) is imperative for their unique advantages of eliminating detrimental dopants and enabling compatible processes with tandem cells in comparison with the regular structures. However, the progress of this structure lags due to its relatively low open circuit voltage (V oc). Herein, we present an effective surface passivation strategy using phenethylammonium iodides with a different side group to ameliorate the aforementioned issues. It has been observed that 4-methyl phenethylammonium iodide (MePEAI) with the –CH 3 side group can effectively reduce the trap density of the perovskite film by forming interactions with the under-coordinated Pb2+ ions, thereby suppressing the nonradiative recombination. Additionally, this approach optimizes the energy-level alignment at the perovskite/PCBM interface. As a result, the optimized device demonstrates a substantially enhanced efficiency from 11.23 to 14.10 %. Furthermore, the MePEAI-treated device exhibits excellent long-term stability. The unencapsulated device retains 81.2 % of its initial power conversion efficiency (PCE) after being stored for over 2900 h in an N 2 atmosphere. [Display omitted] TOC GRAPHICS. [ABSTRACT FROM AUTHOR]

• Using ultrasonic and NH 4 + assisted electrodeposition to prepare MnO 2 electrode. • Ultrasonic and NH 4 + induce Ni in Ni substrate forming NiO. • NiO and MnO 2 are evenly compounded to rise greatly the electrode performance. • MnO 2 shows a high specific capacitance of 810 F g−1 at a current density of 1 A g−1. • The synergistic effect of NiO and MnO 2 is study. Electrodeposition has become a common technology for the preparation of MnO 2 supercapacitor materials. However, it was still difficult for MnO 2 to obtain high specific capacitance without any assistant technology, and most reports showed only 200–450 F g−1 as the load mass over 0.5 mg cm−2. In this work, we proposed ultrasound and NH 4 + assisted one step electrodeposition to prepare high-performance MnO 2 (UN-MnO 2) on Ni foam and explored relevant mechanisms. We also systematically studied the influence of ultrasound, the NH 4 + concentration, and the loading mass on the microstructure and electrochemical performance of MnO 2. The UN-MnO 2 electrode exhibits a high specific capacitance of 810 F g−1 at a current density of 1 A g−1 (1.0 mg cm−2, 630.8 mF at the scan rate of 5 mV/s). After 5000 cycles, the specific capacitance remains at 88.45% of the initial value. The assembled symmetric supercapacitor (SSC) based on UN-MnO 2 electrode can reach a high energy density of 58.3 Wh kg−1 (at a power density of 508 W kg−1) and high power density of 7.8 kW kg−1 (at an energy density of 26.8 Wh kg−1). This work demonstrates a simple and low-cost method, providing a good idea for the preparation of high-performance MnO 2. [ABSTRACT FROM AUTHOR]

MnO 2 and MnO 2 /Reduced graphene oxide composite electrodes with different electrodeposition time after alcohol infiltration were prepared by a simple electrochemical deposition method without any binder under argon atmosphere. Scanning electron microscope, transmission electron microscope, X-ray photoelectron spectroscopy and other analytical methods were used to analyze the morphology, microstructure and other properties of the composite material. Galvanostatic charge-discharge, Cyclic Voltammetry, Chronoamperometry and Electrochemical impedance spectroscopy were used to assess the electrochemical performance of the prepared electrodes. MnO 2 /RGO composite electrode deposited in a short time (50 s) has excellent electrochemical performance, the specific capacitance can maintain 175 F g−1 at a high current density of 20 A g−1, and the energy density can reach 41.27 Wh Kg−1 (1 A g−1). In addition, it has lower charge transfer resistance in 1 M Na 2 SO 4 solution (0.22 Ω). • High quality MnO 2 /RGO were electrodeposited on three-dimensional porous foam nickel. • The effects of different electrodeposition time were investigated. • The MnO 2 /RGO/Ni is used as binder-free electrode for supercapacitor. • MnO 2 /RGO/Ni electrode has high rate performance and cycle performance. • MnO 2 /RGO/Ni has a very low solution resistance and charge transfer resistance. [ABSTRACT FROM AUTHOR]

In this paper, Fe/C codoped TiO2 powders are successfully synthesized by the sol‐gel method. The crystalline size and interplanar spacing of doped TiO2 were smaller than undoped TiO2 powders. The narrow bandgap of TiO2 powders were observed by doping and the light absorption edge shift to longer wavelength, especially for Fe/C codoped TiO2 powders, and extended to 460 nm. Photoluminescence spectra showed similar luminescence band shape except for relative intensity under the excited source of 320 nm and Fe/C codoped TiO2 powders exhibited the weakest luminous intensity. Compared with undoped powders, doped TiO2 could significantly improve the photocatalytic degradation in methyl orange aqueous solution, and Fe/C codoped TiO2 powders exhibited optimal performance among other photocatalyst under ultraviolet light irradiation and also showed better stability in the air environment. If the energy of incident light was greater than the bandgap of TiO2, electronics on the valence band would divert into the conduction band, and then electron‐hole pairs were achieved. Hole occurred oxidation reaction, and the electrons occurred reduction reaction with the organic solvent when carriers migrated from the inside to the surface of the powders; finally, hydroxyl radicals and superoxide radicals would be generated, which changed the organic compounds into inorganic small molecules [ABSTRACT FROM AUTHOR]

Cs3Bi2I9 (CBI) is a promising material for direct X‐ray detectors. However, for the solution method, due to the difference in the chemical potential of Cs+, Bi3+, I− ions in the solvent, the composition of CBI single crystals (SCs) prepared by the solution method often deviates from the stoichiometric ratio, resulting in the formation of many defects in the material, which degrades the quality of the SC. Herein, Br− and Cl− are used as dopants to produce CBI SCs by the top seed solution method. It can be speculated that the dopant ions can reduce the VI defects in the CBI by means of density functional theory calculations. The carrier lifetimes of CBI SCs doped with Br− and Cl− have been increased to 41.7 and 13.0 ns, respectively. Meanwhile, the defect densities of the SCs are reduced to 1.02 × 109 and 1.85 × 109 cm−3, respectively. X‐ray detectors based on Br‐doped CBI and Cl‐doped CBI SCs exhibit high X‐ray sensitivity of 23071.3 and 18525.3 μC Gyair−1 cm−2 at an electric field of 40 V mm−1, respectively. In addition, the X‐ray detection limit reaches 1.07 and 1.35 nGyairs−1 at an electric field of 2.5 V mm−1, respectively. [ABSTRACT FROM AUTHOR]

Accurate mathematical modeling of state of charge (SOC) prediction is essential for battery management systems (BMSs) to improve battery utilization efficiency and ensure a good safety performance. The current SOC prediction framework only considers battery-related features but ignores vehicle information. Additionally, in light of the emergence of time-series Transformers (TSTs) that harness the power of multi-head attention, developing a SOC prediction model remains a significant challenge. Therefore, we introduce a new framework that integrates laboratory battery data with mathematical vehicle model features to improve the accuracy of the SOC and propose a prediction model named DLPformer, which can effectively capture variations in the SOC attributed to both trend and seasonal patterns. First, we apply Matlab/Simulink to simulate a mathematical model of electric vehicles and process the generated vehicle data with Spearman correlation analysis to identify the most relevant features, such as the mechanical losses of the electric motor, differential, and aerodynamic drag. Then, we employ a data fusion method to synchronize the heterogeneous datasets with different frequencies to capture the sudden changes in electric vehicles. Subsequently, the fused features are input into our prediction model, DLPformer, which incorporates a linear model for trend prediction and patch-input attention for seasonal component prediction. Finally, in order to effectively evaluate the extrapolation and adaptability of our model, we utilize different driving cycles and heterogeneous battery datasets for training and testing. The experimental results show that our prediction model significantly improves the accuracy and robustness of SOC prediction under the proposed framework, achieving MAE values of 0.18% and 0.10% across distinct driving cycles and battery types. [ABSTRACT FROM AUTHOR]

The natural dyes were successfully extracted from spinach, pitaya pericarp, orange peel, ginkgo leaf, purple cabbage and carrot, and then fabricated a dye-sensitized solar cells (DSSCs). It suggested that the absorption properties of natural dyes were strongly dependent on the types and concentration of pigments, and the purple cabbage exhibited an obvious absorption at 317 nm. Meanwhile, a higher conversion efficiency of 0.157% was obtained as the DSSCs were prepared by using purple cabbage, but the DSSCs showed a poor performance when the carrot was used as natural dyes, just achieved 0.01%. FTIR spectra revealed that purple cabbage showed a better adsorption properties between TiO2 films and dyes than carrot. The dipping time was further investigated and proved that an optimal dipping time was 6 min, the DSSCs using purple cabbage could achieve 0.146% in photoelectric conversion efficiency. [ABSTRACT FROM AUTHOR]

Usually, the photoresponse performances of zinc oxide based ultraviolet (UV) photodetector can be enhanced by improving the nanostructure of zinc oxide. Here, we demonstrate a kind of weak ultraviolet intensity photodetector which bases on ZnO superstructure doped with graphene quantum dots (ZnO superstructure/GQDs). The ZnO superstructure includes a ZnO nanoflower on the top of ZnO nanorod. The nanoflower has large specific surface area that is favor to the absorption of weak UV light, and the nanorod provides a good route for carriers transport. Also, the GQDs can assist the absorption of UV and the transport of carriers. The photo-response performance of the ZnO superstructure/GQDs we measured is obtained at a working bias of 3 V and an irradiate condition of 50 μW/cm2, under the excitation wavelength 365 nm. The results show that ZnO superstructure/GQDs has a low dark current (40 nA) and a good photocurrent (2.1 μA) in a low irradiation and power supply condition, and we calculate the current ratio of on/off is about 52.5 times. Further, we discuss in-depth the synthesis mechanism of ZnO superstructure and the transport mechanism of photo-generated carriers in this paper. At the same time, we develop a UV signal acquisition and voltage conversion system, which proves the practical application reference of ZnO superstructure/GQDs for weak UV intensity photodetector. [ABSTRACT FROM AUTHOR]

Direct X‐ray detectors require high‐quality and large‐size materials to reduce radiation hazards. As an all‐inorganic lead‐free perovskite, Cs3Bi2I9 has good prospects for research and applications in the field of X‐ray detection. A refined evaporation method is proposed for the growth of Cs3Bi2I9 single crystals (SCs), and a high‐quality SC with a size of 18 × 20.5 × 3 mm3 is obtained. Due to the anisotropy of Cs3Bi2I9 SCs, two different device structures, vertical and coplanar, are designed. The coplanar device has a higher sensitivity of 59 464.4 µC Gyair−1 cm−2, while the vertical device performs better on the limit of detection (LoD), with an LodD as low as 1.27 nGyair s−1. [ABSTRACT FROM AUTHOR]

Abstracts Fabric supercapacitors with mechanical flexible and excellent energy storage capacity attract considerable attention for the potential application in wearable smart electronics. A novel ternary composite electrode and assembled all-solid-state fabric supercapacitors are expected to achieve favorable electrochemical performances. The facile vapor phase polymerization method is employed to fabricate the ternary poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate)/molybdenum disulfide/poly (3,4-ethylenedioxythiophene) composite electrodes. The molybdenum disulfide nanograins are incorporated into the conducting polymer matrix which further facilitates the formation of hierarchical porous structures. On account of profitable synergistic effect among three-component materials and porous structure with reinforced electronic/ionic transport, the as-prepared hybrid electrode exhibits a high areal capacitance of 51.01 mF/cm2 at current density of 0.1 mA/cm2, as well as long cycling durability with 93.6% capacitance retention after 5000 cycles of galvanostatic charge/discharge tests. Furthermore, symmetric fabric micro-supercapacitor assembled by the as-prepared electrodes is also evaluated in a belt-shaped device. This assembled device exhibits an energy density of 0.2 μWh/cm2 (1.81 mWh/cm3) and the power density of 0.09 mW/cm2 (0.82 W/cm3). These results of excellent flexibility and favourable capacitive performance indicate a promising application in portable and wearable electronic devices. Graphical abstract Image 1 Highlights • The highlights of our original work are: • Ternary PEDOT:PSS/MoS 2 /PEDOT film exhibits excellent electrochemical performances. • The superior performance is a result of the synergistic effect of three components. • This ternary composite can be simply coated onto flexible textile substrate. • This flexible fabric electrode based micro-device is suitable for wearable device. [ABSTRACT FROM AUTHOR]

Abstract The effects of side passivation with different functional groups (H, F and OH) on the electronic and optical properties of GeSe nanobelts (NBs) are investigated using density functional theory. The optimized structures of GeSe NBs are calculated by full optimization method. It is found that with side passivation of the terminators, pristine metallic GeSe NBs can be tuned to be p -typed semiconductors. Further analysis shows that the side terminators causes the shift of electronic bands and the modification of density of states (DOSs) of band edges of GeSe NBs, resulting in different effective masses of charge carriers depending on the terminator types. The study of optical properties of GeSe NBs shows that the main absorption peaks are modulated by side passivation of the terminators, and quantum yields of side passivated GeSe NBs are evidently bigger than those of pristine ones mainly because passivated ones have suitable band gap values. Our calculated results demonstrate that the electronic and optical properties of GeSe NBs can be effectively tuned by side passivation with functional groups. Highlights • Pristine metallic GeSe NBs can be designed to be p-typed semiconductors with side passivation of typical terminators. • Evident modulation of effective masses of charge carriers can be achieved by shift of electronic bands and modification of DOSs of band edges caused by side passivation. • Side-passivated GeSe NBs have bigger quantum yields than pristine ones because passivated ones have suitable band gap values. [ABSTRACT FROM AUTHOR]

In this work, we prepared the thermal evaporated amorphous selenium (a-Se) thin films with different evaporation time at low vacuum degree 10-2 Pa. The results showed a-Se thin films were easier to be crystallized with prolonging evaporation time. Also, the transmittance absorption edges of a-Se thin films showed a blue shift with the enhanced optical energy gap from 2.08 eV to 2.15 eV. Further, the dark current was found to depend on energy gap, and became lower as extending evaporation time. Moreover, a-Se thin films showed the improved X-ray photocurrent gain, with a rapid photoresponse and a small applied voltage requirement. Overall, this work revealed that the increase of evaporation time led to better deposition quality of thin films, enhancing energy gap and X-ray photoresponse, but thin films were not able to resist to higher temperature anymore. [ABSTRACT FROM AUTHOR]

Graphene is widely used in tunable photonic devices due to its numerous exotic and exceptional properties that are not found in conventional materials, such as high electron mobility, ultra-thin width, ease of integration and good tunability. In this paper, we propose a terahertz metamaterial absorber that is based on patterned graphene, which consists of stacked graphene disk layers, open ring graphene pattern layers and metal bottom layers, all separated by insulating dielectric layers. Simulation results showed that the designed absorber achieved almost perfect broadband absorption at 0.53–1.50 THz and exhibited polarization-insensitive and angle-insensitive characteristics. In addition, the absorption characteristics of the absorber can be adjusted by changing the Fermi energy of graphene and the geometrical parameters of the structure. The above results indicate that the designed absorber can be applied to photodetectors, photosensors and optoelectronic devices. [ABSTRACT FROM AUTHOR]

An amorphous state makes the material free of interface and ensures the overall uniformity of the material and device, to the benefit of large-area electronic devices, such as amorphous silicon and indium gallium zinc oxide display devices and amorphous selenium flat panel detectors. Elements with high atomic number endow the PbO-Ga 2 O 3 system materials with high X-ray absorption coefficients, and wide band gap leading to a low dark current and high signal-to-noise ratio. These advantages are in line with the criteria for a practical X-ray detector development. Herein, the direct photon-charge conversion X-ray detectors based on fully amorphous bulk PbO-Ga 2 O 3 system [(PbO) x (Ga 2 O 3) 1- x (x = 0.698, 0.747, 0.761, 0.789)] was fabricated by using high-temperature melt quenching method. Under a fixed electric field of 100 V/mm and X-ray irradiation dose rate of 0.57 μGy ms−1, the dark current as low as 1.1 pA mm−2, photocurrent up to 1600 pA mm−2, signal-to-noise ratio up to 800, comparable sensitivity as 2.02 μC Gy−1 cm−2 of the as fabricated X-ray detector were obtained. All the results suggest that amorphous bulk PbO-Ga 2 O 3 system materials are potential candidates for developing of direct photon-charge conversion X-ray detectors. An amorphous state makes the material free of interface and ensures the overall uniformity of the material and device, gaining much attention in large-area display and imaging devices. In this work, the direct photon-charge conversion X-ray detectors based on a new kind of fully amorphous bulk PbO-Ga 2 O 3 system material present excellent detection performance. [Display omitted] [ABSTRACT FROM AUTHOR]

Amorphous selenium (a-Se) thin films with a thickness of 1200 nm were successfully fabricated by thermal evaporation at a low vacuum degree of 10-2 Pa. The structural properties involving phase and morphology showed that a-Se thin films could be resistant to 60 °C in air. Also, a transformation to polycrystalline Selenium (p-Se) was shown as the annealing temperature rose to 62 °C and 65 °C, with obvious changes in color and surface morphology. Moreover, as the a-Se transformed to p-Se, the samples' transmittance decreased significantly, and the band gap declined dramatically from 2.15 eV to 1.92 eV. Finally, the X-radiation response of a-Se was investigated as an important property, revealing there is a remarkable response speed of photogeneration current both X-ray on and X-ray off, with a requirement of only a very small electrical field. [ABSTRACT FROM AUTHOR]

A promising flexible X-ray detector based on inorganic semiconductor PbI2 crystal is reported. The sliced crystals mechanically cleaved from an as-grown PbI2 crystal act as the absorber directly converting the impinging X-ray photons to electron hole pairs. Due to the ductile feature of the PbI2 crystal, the detector can be operated under a highly curved state with the strain on the top surface up to 1.03% and still maintaining effective detection performance. The stable photocurrent and fast response were obtained with the detector repeated bending to a strain of 1.03% for 100 cycles. This work presents an approach for developing efficient and cost-effective PbI2-based flexible X-ray detector. [ABSTRACT FROM AUTHOR]

This review gives a full-scale and in-depth summary of CsPbX3 perovskite materials from basic properties to photovoltaic applications. [Display omitted] Compared with organic–inorganic hybrid halide perovskites (OIHPs), inorganic cesium lead halide perovskites (CsPbX 3) possess superior intrinsic stability for high temperatures and are considered one of the most attractive research hotspots in the perovskite photovoltaic (PV) field in the past several years. The PCE of CsPbX 3 inorganic perovskite solar cells (IPSCs) has increased from 2.9% in 2015 to more than 20% with excellent stability. There are still many on-going studies on the properties of perovskite materials and their applications in PV technology, thereby needing a thorough understanding. Here, the progress of inorganic perovskites is systematically introduced, including the fundamental properties of CsPbX 3 materials and CsPbX 3 -based PV devices. The origins of stability and instability of CsPbX 3 and defects in CsPbX 3 are discussed. CsPbI 3 -, CsPbI 2 Br-, CsPbIBr 2 - and CsPbBr 3 -based PV devices and performance are comprehensively reviewed. The stabilization methods and mechanism for the photoactive phases of inorganic perovskites with low bandgap are emphasized. Reported strategies to boost the performance of CsPbX 3 -based IPSCs are summarized. In the end, the potential of inorganic perovskites is evaluated, which opens up new prospects for the commercialization of IPSCs. [ABSTRACT FROM AUTHOR]

Resource management of deep learning training (DLT) jobs is critical for cluster resource efficiency and client QoS assurance. Most existing scheduling frameworks require clients to specify job resource configuration, which can lead to over-provision or under-provision issues. Additionally, the performance of some static scheduling frameworks degrades in highly dynamic clusters. In this paper, we propose a Qo S-aware joint re source optimization framework called Qore-DL for distributed DLT jobs. We divide the lifecycle of a DLT job into submission, queuing and running stages. Qore-DL automatically configures reasonable resources for submitted jobs and greedily assigns scheduled jobs to hosts. For running jobs, Qore-DL employs a heuristic scheme to adjust their resources. Qore-DL jointly considers the optimization of QoS satisfaction and resource efficiency at the three stages of DLT jobs. We implemented the prototype of Qore-DL in TensorFlow based on Kubernetes and conducted extensive experiments in CPU and GPU clusters to evaluate its performance. The experiment results show that, compared with its counterparts, Qore-DL can improve the job completion rate by up to 42.4% and the cluster resource efficiency by up to 21.8%. [ABSTRACT FROM AUTHOR]

Using bilayer graphene structures (L-type and disk-type structures), we numerically demonstrate a tunable single-band terahertz metamaterial absorber with nearly perfect (100%) absorption by continuously adjusting the graphene Fermi energy parameters to determine the maximum absorption rate, the corresponding center frequency, and bandwidth. Graphene distinct dielectric–metal transition properties make it possible to achieve tunable terahertz absorption. The maximum absorption rate increases from 18% to 100% when the Fermi energy is increased from 0.1 to 1 eV. At 1 eV, the absorption rate exceeds 90% in the range of 0.57–1.03 THz. The incident angle is also tested. When the angle is in the range of 60°, excellent adsorption performance is maintained. [ABSTRACT FROM AUTHOR]

In this work, we report on the results of the electrical behavior of coplanar electrode structure X-ray detector based on PbI2 crystal. The detector with coplanar electrode similar to the Van der Pauw structure instead of conventional planar structure can partly reduce the influence of trapping effect to charge carrier transport along the $c$ -axis. According to the configuration, four operating modes of the detector were thoroughly studied. Several novel results, such as the negative polarity dark current and photocurrent under zero bias voltage, orientation polarization, short relaxation time of steady-state surface leakage current and fast photocurrent response are obtained by this kind of coplanar structure configuration. The detector has the potential to be developed as a solid state X-ray dosimeter in the medical radiation environment, providing a high sensitivity and good adaptability under positive or negative bias voltage. [ABSTRACT FROM PUBLISHER]

Existing closed sequential pattern mining generates a more compact yet complete resulting set compared with general sequential pattern mining. However, conventional closed sequential pattern mining algorithms pose a great challenge at spawning a large number of inefficient and redundant patterns, especially when using low support thresholds or pattern-enriched databases. Driven by wide applications of sequential patterns with contiguous constraint, we propose CCSpan ( C losed C ontiguous S equential pa tter n mining), an efficient algorithm for mining closed contiguous sequential patterns, which contributes to a much more compact pattern set but with the same information w.r.t. closed sequential patterns. Moreover, with the shorter feature of patterns, the closed contiguous sequential patterns are preferred for feature selection and sequence classification based on the Minimum Description Length principle. CCSpan adopts a novel snippet-growth paradigm to generate a series of snippets as candidates, each of which is attached with a set of item(s) that precisely record the pattern’s occurrences in the database, and CCSpan leverages three pruning techniques to improve the computational efficiency significantly. Our experiments based on both sparse and dense datasets demonstrated that CCSpan is efficient and scalable in terms of both database size and support threshold. [ABSTRACT FROM AUTHOR]

PbI 2 polycrystalline thin films have been prepared by using a thermally physical vapor phase growth in vacuum. X-ray diffraction measurement and atomic force microscope analysis show that the structural change of the films occurs depending on growth condition. The width of the Urbach tail of the films indicates that the disordered structure inside the grains changes relying on preparation condition. It is found that the structure of the films is sensitive to growth parameter. A microstructure evolution model with respect to grain orientation is developed to explain the morphological and structural variation process during the films growth. [ABSTRACT FROM AUTHOR]

We report a controllable, economical and rapid preparation of amorphous selenium (a-Se) thick films by using e-beam evaporation technique. Characterization including X-ray diffraction, Raman and FTIR spectroscopy confirm the amorphous nature of the as-grown films. The films in thickness as high as 267 µm were obtained with a deposition rate of 2.11–2.3 µm/min. A Raman shift peak at 252.4 cm −1 and the absorption of the vibration band at 487.9 and 737.7 cm −1 in FTIR spectra are related to the disordered Se chains and Se 8 rings assigned to a-Se. All the results indicate that the e-beam evaporation is a promising technique for a-Se films fabrication. [ABSTRACT FROM AUTHOR]

We report the experimental study on the electrical characteristics of a flexible device based on PbI2 crystal. It is found that the ohmic contact characteristics remain the same, but the dark current decreased with increasing mechanical tensile strain. The value of the bandgap Eg = 2.28 eV obtained from optical absorption spectra is kept in a steady state during bending, but a widening of the band-tail state occurs. [ABSTRACT FROM AUTHOR]

The bound states in a continuum (BICs) are objective physical phenomena that defy conventional wisdom, and they exist in the radiating continuous spectrum but remain perfectly localized with non-radiation, which is different from the traditional bound states. In this paper, we report in theory and experiment the high thickness all-silicon terahertz (THz) metasurfaces supporting BIC and quasi-BIC, which is realized by simple pairs of elliptical pillars. Meanwhile, we used an extra optical pump to modulate the transmission amplitude difference between BIC and quasi-BIC metasurfaces, to complete the active control from "On" state to "Off" state. We utilize the abundant amplitude gradation of metasurfaces with different asymmetric degrees to develop the polarization-dependent THz near-field displaying application that can make the grayscale characteristics of a photograph reappear and also be dynamically controlled at On state to Off state. [ABSTRACT FROM AUTHOR]

Abstract: Lead iodide (PbI2) polycrystalline thick films were fabricated on glass substrates with a conductive indium–tin-oxide layer using a close space deposition technique. The morphology of the as-deposited PbI2 films is typically and highly oriented polycrystalline structure, made up of microcrystal platelets upright on the substrate plane. Two techniques including the surface mechanical cutting and after-growth cadmium telluride coating were employed to improve the films′ surface properties. It was shown that both of the film surface treatment methods markedly decreased the dark current of PbI2 films. The photo-to-dark current ratio of about 2.05 under 241Am γ-ray source with activity of 2.78μCi irradiation was obtained from the film treated using both surface cutting and after-growth CdTe coating. Charge transport characteristics of these films were measured and the hole mobility 7.7×10−2–1.67×10−1 cm2/Vs was estimated. [Copyright &y& Elsevier]

Abstract: Crystallization kinetics of the sputtered SmCo based permanent magnetic films was investigated by differential scanning calorimeter, x-ray diffraction, and atomic force microscope methods. The results show that the apparent activation energy for crystallization is observed as 173.7kJ/mol, and the local activation energy for crystallization decreases with increasing crystal phase transformation fraction in non-isothermal crystallization. For isothermal crystallization, the apparent activation energy for crystallization is 159.8kJ/mol. The local activation energy for crystallization exhibits non-monotonic dependence on the crystal phase transformation fraction. The crystallization mechanism is obtained from the investigation of Avrami exponent and microstructure. [Copyright &y& Elsevier]

Abstract: The magnetic field along the central axis for an axially magnetized permanent magnetic ring was investigated by analytical and finite element methods. For open magnetic rings, both calculated and measured results show that the existence of the radial magnetic field creates a remarkable cosine distribution field along the central axis. A new structure of periodic permanent magnet focusing system with open magnetic rings is proposed. The structure provides a satisfactory magnetic field with a stable peak value of 120mT for a traveling wave tube system. [Copyright &y& Elsevier]

PbI2 crystal is a typical layered material with a I–Pb–I monolayer as a repeating unit. Benefiting from the coexistence of ionic and van der Waals bonding, the crystal exhibits low hardness and a low Young's modulus, slips easily along the a–b plane, and is endowed with inherently high flexibility. In this work, bendable three-dimensional (3D)-structured x-ray photodetectors based on PbI2 crystal were prepared, and finite element simulation was employed to reveal the von Mises stress distribution from the surface to the bulk of the crystal, indicating the bending stress associated with the crystal's thickness. The uniformly distributed electric bias field inside the crystal constrains the carrier transport process, provides a consistent geometric variation and electrical contact between the crystal and the electrodes, and further ensures a high effective collection area and enhanced collection capacity for photocarriers, even when the device is subjected to bending. The degradation percentage of the sensitivity after 100 bending cycles is 12.7% and 6.6% for thick (100 μm) and thin (10 μm) samples, respectively. All the simulated and experimental results indicate that PbI2 crystal, when used to construct a 3D-structured device of appropriate thickness, is a promising candidate for the development of flexible x-ray photodetectors. [ABSTRACT FROM AUTHOR]

LiNi 0.5 Mn 1.5 O 4 (LNMO) is a promising high-performance lithium-ion battery cathode material. We synthesized various structures of LNMO precursors based on two calculations, using the solution combustion method with different fuel ratios. The precursors were annealed for a short time under ambient atmospheric conditions, and various polyhedral structures of LNMO samples were formed through natural oxygen absorption. The results reveal that lower fuel ratios (0.2) cause the samples having incomplete crystal structures and severe particle aggregation, resulting in higher polarization and poorer electrochemical performance. Samples with higher fuel ratios (0.8) exhibit complete crystal structures, lower polarization, and excellent rate performance. At 20 C, the electrochemical capacity of sample with fuel ratios (0.8) can reach 90.47 mAh/g. Samples with theoretical fuel ratios (0.5) show the best electrochemical cycling performance, capacity retention, and cycling stability. After 200 cycles at 1 C, the electrochemical capacity still maintains 123.08 mAh/g, with a capacity retention rate of 96.5%. The results indicate that the formation of the precursor, oxygen absorption during annealing, polyhedral structures, different redox couples, and stability of the electrode/electrolyte interface have significant effects on the electrochemical performance. In summary, our research provides insights into the solution combustion synthesis of high-performance LNMO cathode materials, emphasizing the importance of accurate calculation of synthesis parameters to achieve optimal electrochemical performance. [Display omitted] • The fuel ratios are calculated and adjusted to obtain different precursors to optimize the electrochemical performance. • There is a correlation between the formation of LNMO polyhedral structures and the oxygen uptake of different precursors. • Specific fuel ratios for superior electrochemical cycling performance, capacity retention and cycle stability. • Accurate calculation and optimization of the solution combustion method are important for the synthesis of LNMO. [ABSTRACT FROM AUTHOR]

The preparation of Mn-doped Fe 3 O 4 was carried out using the low-temperature combustion synthesis (LCS) method through the addition of Mn2+ to the ferric nitrate-glycine system. Here, we investigate the mechanism of the redox reaction involving Fe3+ and Mn2+ ions, and the results reveal that for the synthesis of porous Mn-doped Fe 3 O 4 , the presence of Mn2+ in the raw material is necessary. The carbon source, such as ethylene glycol, glucose, and polyethylene glycol-4000, serves as both reducing and complexing agent, leading to the formation of more pores during the combustion reaction. Increased specific surface area of combustion products. By conducting a LCS reaction in a solution with added ethylene glycol, Mn-doped Fe 3 O 4 was obtained for lithium ions batteries as anode material, at current density of 5 A g−1, it demonstrates an impressive capacity retention rate of 90% with a high capacity of 452.5 mA h g−1 after 650 cycles. Similarly, Mn-doped Fe 3 O 4 obtained with the addition of polyethylene glycol shows a capacity retention rate of 89.7% after 1500 cycles. Our findings provide a new and innovative method for the preparation of manganese ferrites with a porous structure and a new research approach for developing metal oxide anode materials. • (1)Low-temperature combustion effectively disrupts the ion equilibrium in the solution through the presence of Mn2+, facilitating the formation of Mn-doped Fe 3 O 4. • FM/E electrode material demonstrates a remarkable reversible capacity of 452.5 mA h g−1 (at 5 A g-1, after 650 cycles). • This study introduces a simple and efficient method for using Mn-doped Fe 3 O 4 as anode oxides in lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Large-area and high-crystallinity CdZnTe (CZT) thick films are grown by physical vapor transport and vacuum thermal evaporation (PVT-VTE) hybrid method. The structure, morphology and composition of which are characterized by X-ray diffraction, scanning electron microscope, energy dispersive spectroscopy and X-ray photoelectron spectroscopy. The as-grown CZT thick films are polycrystalline with (111) preferential orientation, which has a dense pyramid surface structure and a thickness of 590 μm. An 8 × 8 array pixilated X-ray detector is fabricated based on the CZT thick film. The average dark resistivity of 8 pixels on the detector diagonal is up to 3.33 × 1011 Ω cm. The estimated mobility-lifetime product of the CZT array detector is 0.72 × 10−2 cm2V−1. Film structure makes the corresponding detector reduce the influence of trapping effect on the charge carrier transport along the grain growth direction, which shows a short relaxation time and fast photocurrent response. The results demonstrate that the CZT thick film based array detector has high resistivity and sensitivity, and the potential to develop X-ray detection and imaging device under room temperature environment. • Large-area and high-crystalline CZT thick films are grown via PVT-VTE hybrid method. • An 8 × 8 array detector was fabricated based on the CZT thick film. • The average dark resistivity of the array detector is up to 4.24 × 1010 Ω cm. • The CZT array detector has a good imaging performance. • The photocurrent has a linear relationship with the number of coppers. [ABSTRACT FROM AUTHOR]

It is one of the effective methods to modulate Fano resonance intensity by adding the thin photoactive material in the Fano metadevice and then light pumping them. However, most photoactive materials not only depend on high power femtosecond pulse, but also violently destroy the initial Fano resonance, thus deteriorating the modulated amplitude range (less than 0.35 in previous reports). This study introduces a terahertz (THz) Fano resonator based on Si photoactive substrate (SPS) which is modulated by low power 1064 nm continuous wave without additional photoactive materials. 90% modulation depth and the 0.45 modulated amplitude range are obtained by this device with only 2 mW (0.064 W cm−2) pump power. Meanwhile, this study also perfectly solves a long‐neglected problem, i.e., the Fano resonance amplitude of the whole sample seriously deviates from the Au metasurface. At first, the influence of SPS thickness on Fano resonance is investigated, which reveals that SPS thickness low to 3–0.5 µm is required in order to achieve basically the same between Fano resonance of the whole sample and the Au metasurface. And this device shows sharper initial Fano resonance and obtains a higher modulation amplitude range of 0.65 at this time. [ABSTRACT FROM AUTHOR]

Well-aligned ZnO nanorods (NRs) arrays were grown on ZnO seed layer/ITO substrate using chemical bath deposition (CBD) technique and then fabricating ultraviolet (UV) photodetectors (PDs). The effect of precursor concentration of sols on the properties of ZnO seed layer was investigated, and indicated that the crystallinity and growth orientation of samples depend significantly on precursor concentration. ZnO NRs deposited on seed layer exhibit hexagonal wurtzite structure and found that changing the concentration not only affects seed layer, but also influence the rods growth, making it possible to improve the aspect ratio and crystallinity of ZnO NRs. Moreover, the performance of PDs was further discussed and suggested that the maximum signal-to-noise ratio (SNR) and sensitivity (S) of PDs are 67 dB and 2348, when the concentration is 0.5 mol/L, also the shortest rise time of 0.993 s and fall time of 2.036 s can be obtained in such preparation conditions, which is related to larger aspect ratio and higher crystal quality of ZnO NRs. The fabricated UV PDs with high performance are helpful to its application in ultraviolet astronomy, fire detection, especially in military fields, and also are promising for large-scale production. • Vertically aligned ZnO nanorods arrays were prepared by hydrothermal method. • The aspect ratio of obtained ZnO nanorods is up to 14.69 • UV detectors based on ZnO NRs show high response performance. • The signal-to-noise ratio (SNR) and sensitivity of device are 67 dB and 2348. [ABSTRACT FROM AUTHOR]

Rational design of electrode materials and facile synthetic process are essential for developing high performance energy storage devices. Here, a novel reduced graphene oxide/molybdenum disulfide/poly (3,4-ethylenedioxythiophene) ternary material is constructed and deposited on carbon fiber cloth by a facile hydrothermal polymerization method. Thereinto, the graphene oxide is directly used as an oxidant to initiate the polymerization of 3,4-ethylenedioxythiophene. Meanwhile, graphene oxide is transformed into reduced graphene oxide subsequently. This unique ternary flexible electrode exhibits a remarkable areal capacitance of 241.81 mF/cm2 at a current density of 0.5 mA/cm2 as well as good stability with 93.7% capacitance retention after 5000 cycles. The excellent electrochemical properties can be attributed to the profitable synergistic effect among three components. Reduced graphene oxide as a framework provides improved electrical conductivity network. Molybdenum disulfide and poly (3,4-ethylenedioxythiophene) afford large pseudocapacitance. Moreover, the ternary electrode possesses porous folded structures which can reinforce the electronic/ionic transport and result in the conspicuous increase in areal capacitance. In addition, the assembled fabric micro-supercapacitor based on the ternary electrodes delivers a superior energy density of 1.44 μWh/cm2 at a power density of 0.058 mW/cm2. This as-prepared device with excellent flexibility and favorable capacitive performance demonstrates a promising wearable energy storage device. [ABSTRACT FROM AUTHOR]

The physical Schottky parameters of devices based on Schottky contact are important to analyze the working mechanism. This article theoretically studies the parameter characteristics of the current–voltage curve of two back‐to‐back connected Schottky contacts via the thermionic emission model, and it is found that not all the parameters are able to be extracted under some constraints. Compared with some classical extraction methods, a straightforward strategy to approach the Schottky intrinsic parameters by solving equations during the characteristic interval are presented. In addition, this method is verified on several representative standard curves and experimental curves, and the extracted parameters are highly compatible with those curves. The current extraction method will be of great significance for the design and preparation of Schottky‐based devices. [ABSTRACT FROM AUTHOR]

Usually, ZnO thin films used in ultraviolet photodetector exhibit good photoresponse property when ultraviolet signal is strong enough. However, due to the high dark current, pure ZnO is insusceptible to weak ultraviolet signal. To address this problem, lithium-doped ZnO (LZO) thin films were prepared using the sol-gel method in this study. Results revealed that the LZO thin film doped with low concentration (2 at.%) had a dark current about 10 times lower than the pure ZnO. In addition, the ultraviolet with a low irradiance of 90 μW/cm2 was used. According to the results of the investigations on the external quantum efficiency and responsivity, the inherent photocurrent generation ability of ZnO was not deteriorated through low concentration lithium doping. LZO thin film doped with 2 at.% exhibited a high sensitivity to weak ultraviolet signal --- the signal-to-noise ratio was enhanced by approximately 10 times compared with that of pure ZnO. This study indicates that LZO thin films with low doping concentration are promising application on weak ultraviolet signal photodetector. • Li atoms with 2 at.% are doped into ZnO thin films, showing substitute mode. • The dark current of LZO is about 10 times less than pure ZnO. • Further, the signal-to-noise ratio of LZO enhances to about 10 times. • LZO thin films achieve a high sensitivity for the weak UV signal detection. [ABSTRACT FROM AUTHOR]

ZnO films prepared by sol-gel method and the ultraviolet detectors based on this material have been investigated in this paper. X-ray diffraction (XRD) patterns showed ZnO films present hexagonal wurtzite structure with a preferential orientation of (002) plane, and the crystallite size of films gradually increased from 44.3 to 54.8 nm as the annealing temperature increased from 400 to 600 °C. Ultraviolet-visible (UV-Vis) spectra indicated that the optical band gap decreases gradually with the increase of annealing temperature, and the minimum band gap is 3.06 eV at 600 °C. Photoluminescence (PL) spectra revealed that increasing annealing temperature can significantly reduce the defects and improve the crystallinity. Finally, gold (Au) coplanar interdigital electrodes were deposited on ZnO film surface and used to fabricate the ultraviolet photodetectors. The response performance of the devices improved as the annealing temperature of ZnO films increased, and the fastest response speed with a rise time of 4.172 s and a fall time of 11.012 s was obtained. [ABSTRACT FROM AUTHOR]

A key challenge to software product line engineering is to explore a huge space of various products and to find optimal or near-optimal solutions that satisfy all predefined constraints and balance multiple often competing objectives. To address this challenge, we propose a hybrid multi-objective optimization algorithm called SMTIBEA that combines the indicator-based evolutionary algorithm (IBEA) with the satisfiability modulo theories (SMT) solving. We evaluated the proposed algorithm on five large, constrained, real-world SPLs. Compared to the state-of-the-art, our approach significantly extends the expressiveness of constraints and simultaneously achieves a comparable performance. Furthermore, we investigate the performance influence of the SMT solving on two evolutionary operators of the IBEA. [ABSTRACT FROM AUTHOR]

Abstract In this paper, the effect of sputtering distance between target and substrate (D TS) on the structural, morphological and optical properties of TiO 2 films were investigated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed that crystallite size and surface morphology were strongly dependent on D TS. The X-ray photoelectron spectroscopy (XPS) results showed that obvious three peaks including C1S, Ti2p and O1s could be clearly observed and the binding energy was 285, 458 and 531 eV, respectively. For each sample, four peaks near 386, 462, 527 and 595 nm in photoluminescence (PL) spectra were observed and originated from intrinsic recombination, F center, F+ center and electrons transferred from 3d Ti3+ states to the deep levels OH−, respectively. Finally, the photoresponse properties of UV detectors based on TiO 2 films were analyzed and the TiO 2 UV detector prepared at a D TS of 80 mm showed high responsivity of 2.02 × 10−4 A/W and excellent photosensitivity of 32.25, also, exhibited a fast response with a rise time (τ r) of 0.98 s and fall time (τ f) of 3.14 s. Highlights • TiO 2 films was successfully prepared by magnetron sputtering technology. • Properties of TiO 2 films UV detector were mainly decided by oxygen vacancy. • Device showed a fast response with rise time of 0.98 s and fall time of 3.14 s. • Device showed a high photosensitivity of 32.25. [ABSTRACT FROM AUTHOR]

Abstract Previous reports found Al-doped ZnO nanosheets were formed at a certain preparation condition, but the formation mechanism was vague. In this work, we prepare sol-gel Al-doped ZnO films, and find that films show the obvious nanorods structure on surface of pure ZnO, but the nanorods changes to nanosheets gradually with rising doping concentration. The formation mechanism of nanosheets is clarified, and the doping concentration dependence of morphology is discussed in this paper. In addition, the photoluminescence spectra of all films appear a series of emissions including the near band edge emission (NBE) at 388 nm and several defect emissions (DE) at 396–499 nm. Previous reports proposed that NBE and DE would rise monotonously or decline monotonously with doping. However, this work reveals that the NBE decreases firstly in the range of low doping concentrations and then improves upon excessive doping concentration, due to crystalline quality and optical energy gap --- this reason is different from traditional explanations. Also, DE at different positions show the different variation trends, without the same increase or the same decrease. At excessive doping concentration, both NBE and DE enhance, illustrating the potential application for the enhanced ultraviolet and white light emitting devices. [ABSTRACT FROM AUTHOR]

Nanocrystalline ZnO thin films with the varied thickness were deposited on glass substrate using sol-gel spin coating method, and the different thickness of samples was achieved via changing the number of layers. X-ray diffraction patterns of samples showed the preferential orientation at (002) planeupon coating with 2 layers and the gradual increase in random orientation with coating up to 6 layers. Scanning electron microscopeimages appeared a few layer interfaces for 4 and 6 layers sample, and atomic force microscope images revealed the larger particle size and rougher surfacewith increasing thickness, which showed the obvious effects on optical properties of samples too. The increased absorption and reduced energy gap were found through deducing transmittance curves of samples. Further, photoluminescence characteristic was measured and revealed that there are the best intrinsic emission in ultraviolet region and lowest defect emissions in visible region for the sample coated with 4 layers. [ABSTRACT FROM AUTHOR]