The chemiluminescence （CL） performance of luminol is improved using reduced graphene oxide/gold nanoparticle （rGO-AuNP） nano-composites as catalyst. To prepare this catalyst, we propose a linker free, one-step method to in- situ synthesize rGO-AuNP nano-composites. Various measurements are utilized to characterize the resulting rGO-AuNP samples, and it is revealed that rGO could improve the stability and conductivity. Furthermore, we investigate the CL signals of luminal catalyzed by rGO-AuNP. Afterwards, the size effect of particle and the assisted enhancement effect of rGO are studied and discussed in detail. Based on the discussion, an optimal, sensitive and stable rGO-AuNP-luminon- H202 CL system is proposed. Finally, we utilize the system as a sensor to detect hydrogen peroxide and organic compounds containing amino, hydroxyl, or thiol groups. The CL system might provide a more attractive platform for various analytical devices with CL detection in the field of biosensors, bioassays, and immunosensors.
In this paper, we report a Schottky ultraviolet photodetector based on poly（3,4-ethylenedioxy-thiophene）poly（styrenesulfonate）（PEDOT：PSS） transparent electrode contacts to Mg0.1Zn0.9O. The I-V characteristic curves of the device are measured in the dark condition and under the illumination of a 340-nm UV light. The device shows a typical rectifying behavior with a current rectification ratio of 103 at ±2 V, which exhibits a good Schottky behavior. The phototo-dark current ratio is high, which is 1×103at-4 V. A peak response of 0.156 A/W at 340 nm is observed. The device also exhibits a wide response from 250 nm to 340 nm, with a response larger than 0.1 A/W. It covers the UV-B region（280 nm-320 nm）, which makes the device very suitable for the detection of UV-B light.
The performance of P3HT：PCBM solar cells was improved by anode modification using spin-coated Tb（aca）3phen ultrathin films. The modification of the Tb（aca）3phen ultrathin film between the indium tin oxide （ITO） anode and the PEDOT：PSS layer resulted in a maximum power conversion efficiency （PCE） of 2.99% compared to 2.66% for the reference device, which was due to the increase in the short-circuit current density （Jsc）. The PCE improvement could be attributed to the short-wavelength energy utilization and the optimized morphology of the active layers. Tb（aca）3phen with its strong down-conversion luminescence properties is suitable for the P3HT：PCBM blend active layer, and the absorption region of the ternary blend films is extended into the near ultraviolet region. Furthermore, the crystallization and the surface morphol- ogy of P3HT：PCBM films were improved with the Tb（aca）3phen ultrathin film. The ultraviolent-visible absorption spectra, atomic force microscope （AFM）, and X-ray diffraction （XRD） of the films were investigated. Both anode modification and short-wavelength energy utilization using Tb（aca）3phen in P3HT：PCBM solar cells led to about a 12% PCE increase.
We have researched the performances of organic photovoltaic devices with the bulk heterojunction （BHJ） structure using the organic solution-processable functionalized graphene （SPFGraphene） material as the electron-accepter material and P3OT as the donor material. The structural configuration of the device is ITO/PEDOT：PSS/P3OT：PCBM-SPFGraphene/LiF/A1. Given the P3OT/PCBM （1：1） mixture with 8wt% of SPFGraphene, the open-circuit voltage （Voc） of the device reaches 0.64 V, a short-circuit current density （J^c） reaches 5.7 mA/cm2, a fill factor （FF） reaches 0.42, and the power conversion efficiency （7？） reaches 1.53% at illumination at 100 mW/cm2 AM1.5. We further studied the reason for the device performances improvement In the P3OT：PCBM-SPFGraphene composite, the SPFGraphene material acts as exciton dissociation sites and provides the transport pathways of the lowest unoccupied molecular orbital （LUMO）-SPFGraphene-A1. Furthermore, adding SPFGraphene to P3OT results in appropriate energetic distance between the highest occupied molecular orbital （HOMO） and LUMO of the donoffacceptor and provides higher exciton dissociation volume mobility of carrier transport. We have researched the effect of annealing treatment for the devices and found that the devices with annealing treatment at 180℃ show better performances compared with devices without annealed treatment. The devices with annealed treatment show the best performance, with an enhancement of the power conversion efficiency from 1.53% to 1.75%.
WANG HaiTeng HE DaWei WANG YongSheng LIU ZhiYong WU HongPeng WANG JiGang ZHAO Yu
We report fabrication and characterization of metal-semiconductor-metal photoconductive detectors based on Al-doped ZnO thin films fabricated by radio frequency magnetron sputtering.Optical and structural properties of the thin films were characterized using various techniques.At 6 V bias,a responsivity higher than 4 A/W in the wavelength shorter than 350 nm was obtained,and this responsibility dropped quickly and reached the noise floor in the visible region.Transient response measurement revealed that the detector had a fast photoresponse with a rise time of 9 ns and a fall time of 1.2 μs.
SUN JianDAI QianLIU FengJuanHUANG HaiQinLI ZhenJunZHANG XiQingWANG YongSheng
Ag/ZnO/Zn/Pt structure resistive switching devices are prepared by radio frequency magnetron sputtering.The ZnO thin films are grown at room temperature and 400 C substrate temperature,respectively.By comparing the data,we find that the latter device displayed better stability in the repetitive switching cycle test,and the resistance ratio between a high resistance state and a low resistance state is correspondingly increased.After 104-s storage time measurement,this device exhibits a good retention property.Moreover,the operation voltages are very low:-0.3 V/-0.7 V(OFF state) and 0.3 V(ON state).A high-voltage forming process in the initial state is not required,and a multistep reset process is demonstrated.
In order to investigate the impedance matching properties of microwave absorbers,the ternary nanocomposites of GO/PANI/Fe3O4（GPF） are prepared via a two-step method,GO/PANI composites are synthesized by dilute polymerization in the presence of aniline monomer and GO,and GO/PANI/Fe3O4 is prepared via a co-precipitation method.The obtained nanocomposites are characterized by scanning electron microscopy（SEM）,X-ray diffraction（XRD）,and Fourier transform infrared spectroscopy（FTIR）,respectively.The microwave absorbability reveals enhanced microwave absorption properties compared with GO,PANI,and GO/PANI.The maximum reflection loss of GO/PANI/Fe3O4 is up to-27 dB at 14 GHz with its thickness being 2 mm,and its absorption bandwidths exceeding-10 dB are more than 11.2 GHz with its thickness values being in the range from 1.5 mm-4 mm.It provides that GO/PANI/Fe3O4 can be used as an attractive candidate for microwave absorbers.
Ag/ZnO/Zn/Pt structure resistive switching devices are prepared by radio frequency magnetron sputtering. The ZnO thin films are grown at room temperature and 400 ℃ substrate temperature, respectively. By comparing the data, we find that the latter device displayed better stability in the repetitive switching cycle test, and the resistance ratio between a high resistance state and a low resistance state is correspondingly increased. After 104-s storage time measurement, this device exhibits a good retention property. Moreover, the operation voltages are very low： -0.3 V/-0.7 V （OFF state） and 0.3 V （ON state）. A high-voltage forming process in the initial state is not required, and a multistep reset process is demonstrated.
We report a facile method of synthesizing graphene quantum dots（GQDs） with tunable emission. The as-prepared GQDs each with a uniform lateral dimension of ca. 6 nm have fine solubility and high stability. The photoluminescence mechanism is further investigated based on the surfacestructure and the photoluminescence behaviors. Based on our discussion, the green fluorescence emission can be attributed to the oxygen functional groups, which could possess broad emission bands within the π –π ＊ gap. This work is helpful to explain the vague fluorescent mechanism of GQDs, and the reported synthetic method is useful to prepare GQDs with controllable fluorescent colors.
