高光能农膜转光性能的研究

对高光能农膜的转光性能进行了研究。阐述聚烯烃树脂、转光剂、光稳定剂、流滴剂、着色剂等对转光效能的影响。研制出既转紫光又转绿光的新型高光能农膜。

氧化锌/卟啉复合材料的制备及转光性能研究

合成了氧化锌/卟啉复合材料,用XRD、扫描电镜、红外、热重等方法对材料结构进行了表征;实验结果表明,复合材料及其聚乙二醇膜在625-750nm红光范围内均有较强的荧光发射;因此,氧化锌/卟啉复合材料在农用转光膜领域具有潜在的应用价值。

RhB-金属有机骨架材料的制备及转光性能研究

转光材料可以将紫外光和部分不能起光合作用的可见光转换为作物可以利用的可见光,进而提高农作物对太阳光的利用率,有效增加农作物产量。本文选用荧光染料罗丹明B,将其嵌入到不同有机配体的金属有机骨架中。利用红外和热重对材料进行了结构表征,并对其荧光性能进行了测试。实验结果表明,当激发波长为500 nm,可得到植物光合作用所需的红橙光(600 nm左右)。

玉米淀粉/生物基碳点复合光转换薄膜的制备及性能

以壳聚糖(CS)、N-(2-羟乙基)-乙二胺和无水柠檬酸(CA)为主要原料,通过水热法合成了壳聚糖接枝柠檬酸碳点[P(CS-g-CA)CDs]。然后以玉米淀粉(CST)为基体材料,通过流延法制备了一系列不同P(CS-g-CA)CDs用量的玉米淀粉/壳聚糖基碳点复合光转换薄膜[CST/P(CS-g-CA)CDs5、CST/P(CS-g-CA)CDs10、CST/P(CS-g-CA)CDs20]。采用荧光分光光度计、万能试验机、接触角测量仪和土埋降解实验研究了复合薄膜的光学性能、力学性能、亲水性能和降解性能。结果表明,随着P(CS-g-CA)CDs用量的增加,该复合薄膜的拉伸强度先升高后降低,断裂伸长率整体呈现增加趋势;复合薄膜的接触角从37.50°提高到87.00°,复合薄膜亲水性能下降;纯玉米淀粉薄膜无荧光响应,CST/P(CS-g-CA)CDs20能将374 nm处紫外光区的光转换为459 nm的蓝色荧光,该复合薄膜具有蓝光转光性能;混入难水溶的碳点可以延缓纯玉米淀粉薄膜的降解,延长薄膜使用寿命,实现降解速率可调控。

CdWO_4纳米棒的合成及转光性能研究

以Cd（NO3）2·4H2O和Na2WO4·2H2O为原料,采用水热法合成了高荧光性CdWO4纳米棒,并通过X射线粉末衍射、扫描电子显微镜及荧光光谱对其进行了表征,系统地研究了体系的p H值及乙醇添加量对合成产物的物相、形貌和下转换发光性能的影响。结果表明：在p H值为5-9的范围内,能得到单斜晶系的CdWO4纳米棒,当激发波长为297nm时,所得样品均在400-550 nm有很强的发射峰。在水体系中引入乙醇后,所得Cd WO4纳米棒变细,随着乙醇量的增加,样品发光强度逐渐增大。

巯基-双键点击反应制备光固化红光转光膜及其性能

本研究将不同含量的稀土转光剂与含巯基和双键单体共混制备了光固化树脂,然后经巯基-双键或双键-双键点击反应制备了两种农用转光膜,通过荧光光谱、UV光谱、SEM、拉伸性能测试等对转光膜的结构与性能进行表征。研究结果表明,添加0.5%(质量分数)稀土转光剂的转光膜能将波长为353 nm的紫外光转换为波长为613 nm和617 nm的红光,且该转光膜具有良好的透光性能和力学性能,拉伸强度达到12.72 MPa,在农业大棚、玻璃温室等方面具有良好的应用前景。

含[Eu(hfa)_(3)(TPPO)_(2)]的紫外转红光聚乙烯膜的制备、表征及性能研究

文章制备了含不同浓度转光剂[Eu(hfa)_(3)(TPPO)_(2)]的线性低密度聚乙烯(LLDPE)转光膜,并对其性能进行评估。扫描电子显微镜(SEM)结果表明:含[Eu(hfa)_(3)(TPPO)_(2)]的聚乙烯薄膜表面光滑,表面无颗粒物团聚。荧光光谱结果显示:转光膜在紫外区(200~345 nm)被激发,在红光区(600~700 nm)有强发射,发光范围与叶绿素的吸收范围相匹配,表明该转光膜可以吸收太阳光中对植物生长有害的紫外光,转换成植物生长需要的红光,有效实现光质调控。含1.0%[Eu(hfa)_(3)(TPPO)_(2)]的转光膜具有最高的荧光量子产率(66.38%)。自然光下,透过转光膜的光合光子通量密度(PPFD)在红光区提升,表明薄膜具有良好的转光性能。紫外-可见透射光谱显示:转光膜与纯LLDPE膜相比,透光性略微下降,表明转光膜具有良好的透光性。

Effect of sputtering conditions on growth and properties of ZnO :Al films

Al-doped zinc oxide（AZO） films were deposited on glass substrates by mid-frequency magnetron sputtering. The effects of substrate rotation speed and target-substrate distance on the electrical, optical properties and microstructure and crystal structures of the resulting films were investigated by scanning electron microscopy（SEM）, atomic force microscopy（AFM）, X-ray diffraction（XRD）, spectrophotometer and Hall-effect measurement system, respectively. XRD results show that all AZO films exhibit a strong preferred c-axis orientation. However, the crystallinity of films decreases with the increase of substrate rotation speed, accompanying with the unbalanced grains grows. For the films prepared at different target-substrate distances, the uniform microstructure and morphology are observed. The highest carrier concentration of 5.9×1020 cm-3 and Hall mobility of 13.1 cm^2/（V·s） are obtained at substrate rotation speed of 0 and target-substrate distance of 7 cm. The results indicate that the structure and performances of the AZO films are strongly affected by substrate rotation speed.

Regulation of Excited-State Intramolecular Proton Transfer Process and Photophysical Properties for Benzoxazole Isothiocyanate Fluorescent Dyes by Changing Atomic Electronegativity

Excited-state intramolecular proton transfer(ESIPT)is favored by researchers because of its unique optical properties.However,there are relatively few systematic studies on the effects of changing the electronegativity of atoms on the ESIPT process and photophysical properties.Therefore,we selected a series of benzoxazole isothiocyanate fluorescent dyes(2-HOB,2-HSB,and 2-HSe B)by theoretical methods,and systematically studied the ESIPT process and photophysical properties by changing the electronegativity of chalcogen atoms.The calculated bond angle,bond length,energy gap,and infrared spectrum analysis show that the order of the strength of intramolecular hydrogen bonding of the three molecules is 2-HOB<2-HSB<2-HSe B.Correspondingly,the magnitude of the energy barrier of the potential energy curve is 2-HOB>2-HSB>2-HSe B.In addition,the calculated electronic spectrum shows that as the atomic electronegativity decreases,the emission spectrum has a redshift.Therefore,this work will offer certain theoretical guidance for the synthesis and application of new dyes based on ESIPT properties.

Performance analysis of optical burst switching node with limited wavelength conversion capabilities

The systematical and scalable frameworks were provided for estimating the blocking probabilities under asynchronous traffic in optical burst switching(OBS) nodes with limited wavelength conversion capability(LWCC) . The relevant system architectures of limited range and limited number of wavelength converters(WCs) deployed by a share-per-fiber(SPF) mode were developed,and the novel theoretical analysis of node blocking probability was derived by combining the calculation of discouraged arrival rate in a birth-death process and two-dimensional Markov chain model of SPF. The simulation results on single node performance verify the accuracy and effectiveness of the analysis models. Under most scenarios,it is difficult to distinguish the plots generated by the analysis and simulation. As the conversion degree increases,the accuracy of the analysis model worsens slightly. However,the utmost error on burst loss probability is far less than one order of magnitude and hence,still allows for an accurate estimate. Some results are of actual significance to the construction of next-generation commercial OBS backbones.

Effect of substrate rotation speed on structure and properties of Al-doped ZnO thin films prepared by rf-sputtering

Al-doped ZnO(AZO)thin films were deposited on glass substrates by rf-sputtering at room temperature.The effects of substrate rotation speed(ωS)on the morphological,structural,optical and electrical properties were investigated.SEM transversal images show that the substrate rotation produces dense columnar structures which were found to be better defined under substrate rotation.AFM images show that the surface particles of the samples formed under substrate rotation are smaller and denser than those of a stationary one,leading to smaller grain sizes.XRD results show that all films have hexagonal wurtzite structure and preferred c-axis orientation with a tensile stress along the c-axis.The average optical transmittance was above90%in UV-Vis region.The lowest resistivity value(8.5×10?3Ω·cm)was achieved atωS=0r/min,with a carrier concentration of1.8×1020cm?3,and a Hall mobility of4.19cm2/(V·s).For all other samples,the substrate rotation induced changes in the carrier concentration and Hall mobility which resulted in the increasing of electrical resistivity.These results indicate that the morphology,structure,optical and electrical properties of the AZO thin films are strongly affected by the substrate rotation speed.

A Method of Peak Detecting for Nanosecond Pulse in Optical Performance Monitoring System

In optical performance monitoring system,the analog to digital converter is needed to detect the peak of nanosecond pulse and get the signal envelope.A scheme based on a designed anti-aliasing filter and analog to digital converter is proposed to broaden the nanosecond pulse and make it easier for the analog to digital converter to catch the peak of the nanosecond pulse.The experimental results demonstrate that,with the proposed scheme,the optical performance system needs less time to get the recovered eye-diagram of high speed optical data signal,and is robust to phase mismatch in the analog to digital converter circuit.

Transmission Performance of the Optical Millimeter-wave Up-conversion Link Using a Phase Modulator

Numerically analyzed is the transmission performance of the optical millimeter （mm）-wave generated by frequency up-conversion via a phase modulator along the dispersive fiber. 60 GHz ram-wave subcarrier（SC） signals can be obtained after fiber transmission, simultaneously, the phase-modulated signals can be converted to the intensity-modulated ones. The numerical results show that the optical ram-wave at fading loops has better performance, and the eye diagram still keeps open when optical mm-wave signal is transmitted over 98 km.

Impact of photogenerated charge behaviors on luminescence of Eu^(3+) -incorporated microporous titanosilicate ETS-10

A series of Eu3+ -incorporated ETS-10 samples were successfully prepared based on the traditional ion exchange method. The relationship between photogenerated charge behaviors and luminescent properties has been investigated in detail. It has been demonstrated that as a result of the charge transfer from the titanate quantum wires to Eu3+ crystal field states, the host matrix ETS-10 functions as the sensitizer of Eu3+ to enhance the red luminescence, while Eu3+ cations contribute to the recombination of photogenerated charges. The behavior of photogenerated charges has significant impact on the luminescent properties of Eu3+ -incorporated ETS-10 materials.

Carbon nanocomposites with high photothermal conversion efficiency

Photothermal conversion for water vapor gen- eration is a novel strategy and an efficient way to utilize solar energy, which has great potential for water purification and desalination. In this review, the development of photothermal conversion and the classification of absorbers for solar vapor generation systems are presented, especially in recent devel- opment of carbon nanocomposites （carbon nanotubes and graphene） as solar vapor generation devices. Combined with recent progresses and achievements in this field, we discuss the challenges and opportunities for photothermal conversion based on carbon nanocomposites as well as their promising applications.

Photogated proton conductivity of ZIF-8 membranes co-modified with graphene quantum dots and polystyrene sulfonate

Smart proton conductive metal-organic framework(MOF) membranes with dynamic remote control over proton conduction show high potential for use in advanced applications, such as sensors and bioprocesses. Here, we report a photoswitchable proton conductive ZIF-8 membrane by coencapsulating polystyrene sulfonate and graphene quantum dots into a ZIF-8 matrix(GQDs-PSS@ZIF-8) via a solidconfined conversion process. The proton conductivity of the GQDs-PSS@ZIF-8 membrane is 6.3 times higher than that of pristine ZIF-8 and can be reversibly switched by light due to photoluminescence quenching and the photothermal conversion effect, which converts light into heat. The local increase in temperature allows water molecules to escape from the porous channels, which cuts off the proton transport pathways and results in a decrease in proton conductivity. The proton conductivity is restored when the light is off owing to regaining water molecules, which act as proton carriers, from the surroundings. The GQDs-PSS@ZIF-8 membrane responds efficiently to light and exhibits an ON/OFF ratio of 12.8. This photogated proton conduction in MOFs has potential for the development and application of MOF-based protonic solids in advanced photoelectric devices.

New D-π-A dyes for efficient dye-sensitized solar cells

Functional organic dyes have promising prospect in dye-sensitized solar cells as a crucial element, of which sensitizers based on donor-π-acceptor are the most important dyes. On the basis of the structures of the aromatic amine donors such as triphenylamine and indoline, this paper reviews the photoelectric conversion properties of organic sensitizers since 2008, and highlights research work in our laboratory in this area.

Luminescence properties of tunable red-green emitting phosphor Ba2Ca(BO3)2：Eu3＋,Tb3＋

A series of Eu^(3+) or Tb^(3+) doped Ba_2Ca(BO_3)_2 phosphors were synthesized by a high temperature solid state method, and the luminescence properties are investigated. Ba_2Ca(BO_3)_2:Tb^(3+) can show an obvious green emission, and the peak locates at 551 nm, which corresponds to the 5D34→7F5 transition of Tb^(3+). Ba_2Ca(BO_3)_2:Eu+ can present the characteristic emission of Eu^(3+), and the peak locates at 600 nm, which is ascribed to the 5D70→F2 transition of Eu^(3+). In order to achieve the emission-tunable phosphors, the Eu^(3+)/Tb^(3+) co-doped Ba_2Ca(BO_3)_2 are synthesized. When tuning the Eu^(3+) or Tb^(3+) concentration, Ba_2Ca(BO_3)_2:Eu^(3+), Tb^(3+) can both show the tunable emission, which may be induced by the energy transfer from Tb^(3+) to Eu^(3+).

Influence of annealing temperature of ZnO film as the electron transport layer on the performance of polymer solar cells

The surface morphology of Zn O films at different annealing temperatures and the performance of polymer solar cells(PSCs) with Zn O as the electron transport layer are studied.The low temperature sol-gel processed Zn O film has smoother surface than that in higher temperature,which results in the best photovoltaic performance with a power conversion efficiency(PCE) of 3.66% for P3HT:PC61BM based solar cell.With increasing annealing temperature,the photovoltaic performance first deceases and then increases.It could be ascribed to the synergy effects of interface area,the conductivity and surface energy of Zn O film and series resistance of devices.

A series of dithienobenzodithiophene based small molecules for highly efficient organic solar cells

Three acceptor-donor-acceptor （A-D-A） small molecules DCAODTBDT, DRDTBDT and DTBDTBDT using dithieno[2,3-d：2＇,3＇-d＇]benzo[1,2-b：4,5-b＇]dithiophene as the central building block, octyl cyanoacetate, 3-octylrhodanine and thiobarbituric acid as the end groups were designed and synthesized as donor materials in solution-processed photovoltaic cells （OPVs）. The impacts of these different electron withdrawing end groups on the photophysical properties, energy levels, charge carrier mobility, morphologies of blend films, and their photovoltaic properties have been systematically investigated. OPVs device based on DRDTBDT gave the best power conversion efficiency （PCE） of 8.34%, which was significantly higher than that based on DCAODTBDT （4.83%） or DTBDTBDT （3.39%）. These results indicate that rather dedicated and balanced consideration of absorption, energy levels, morphology, mobility, etc. for the design of small-molecule-based OPVs （SM-OPVs） and systematic investigations are highly needed to achieve high performance for SM-OPVs.