The photoluminescence enhancement of electrospun poly(ethylene oxide) fibers with CdS and polyaniline inoculations

Blending electrospinning of cadmium sulfide (CdS) quantum dots (QD) with poly(ethylene oxide) (PEO) solution was employed to fabricate one-dimensional ultrafine fibers with an average diameter of 450 nm. This study focused on systematic investigations into the role of the matrix polymer and the optimal electrospinning parameters for enhancing the photoluminescence properties of fibrous composites. CdS QDs showed a homogeneous distribution within the composite fibers, and fluorescence spectra showed that PEO successfully passivated the interface defects and quenched the visible emission of CdS QDs. The QDs concentration and electrospinning voltage were found to play important roles in enhancing the passivation effect of PEO and adjusting the photoluminescence intensity of the composite fibers. Furthermore, the addition of polyaniline enhanced the photoluminescence intensity of the electrospun fibers, and an electron–hole mechanism was proposed.     

All spray pyrolysis deposited CdS sensitized ZnO films for quantum dot-sensitized solar cells

Sensitized-type solar cells based on ZnO photoanode and CdS quantum dots (QDs) as sensitizers have been fabricated. Both ZnO films and CdS QDs are prepared using ultrasonic spray pyrolysis (USP) deposition technique. This method allows a facile and rapid deposition and integration between CdS QDs and ZnO films without the need for post thermal treatment. The photovoltaic performances of the cells are investigated. The results show that the performance of the cell based on all USP deposited CdS sensitized ZnO photoanode achieves maximally a short circuit current density of 6.99 mA cm⁻² and a power conversion efficiency of 1.54%.     

SURFACE MORPHOLOGY OF SELF-ASSEMBLED VERTICALLY STACKED InAs QUANTUM DOTS BY SIZE-CONTROLLED GROWTH

Structural and optical properties of vertically aligned lnAs quantum dots (QDs) were embedded in Al0.5Ga0.5As spacer layers. The aligned QDs were grown at 520℃ in the Stranski-Krastanow (S-K) growth mode of molecular beam epitaxy. To improve QD characteristics, we employed a size- and density-controlled growth procedure in the upper layers. Measurements by reflection high-energy electron diffraction (RHEED) and atomic force microscopy (AFM) showed that both the size and density of the QDs. The temperature dependence of the wavelength-integrated photoluminescence (PL) intensity revealed the InAs QD emission.     

An optimized multilayer structure of CdS layer for CdTe solar cells application

CdS layers grown by ‘dry’ (close space sublimation) and ‘wet’ (chemical bath deposition) methods are deposited and analyzed. CdS prepared with close space sublimation (CSS) has better crystal quality, electrical and optical properties than that prepared with chemical bath deposition (CBD). The performance of CdTe solar cell based on the CSS CdS layer has higher efficiency than that based on CBD CdS layer. However, the CSS CdS suffers from the pinholes. And consequently it is necessary to prepare a 150 nm thin film for CdTe/CdS solar cell. To improve the performance of CdS/CdTe solar cells, a thin multilayer structure of CdS layer (∼80 nm) is applied, which is composed of a bottom layer (CSS CdS) and a top layer (CBD CdS). That bi-layer film can allow more photons to pass through it and significantly improve the short circuit current of the CdS/CdTe solar cells.     

Substrate Evolution to Microstructural and Optoelectrical Properties of Evaporated CdS Thin Films Correlated with Elemental Composition

A typical high-e fficiency solar cell device needs the best lattice matching between different constituent layers to mitigate the open-circuit voltage loss. In the present work, the physical properties of CdS thin films are investigated where films with 100 nm thickness were fabricated on the different types of substrates viz. soda–lime glass, indium-doped tin oxide(ITO)-and fl uorine-doped tin oxide(FTO)-coated glass substrates, and silicon wafer using electron beam evaporation. The X-ray diffraction patterns confirmed that deposited thin films showed cubic phase and had(111) as predominant orientation where the structural parameters were observed to be varied with nature of substrates. The ohmic behaviour of the CdS films was disclosed by current–voltage characteristics, whereas the scanning electron microscopy micrograph revealed the uniform deposition of the CdS films with the presence of round-shaped grains. The elemental analysis confirmed the CdS films deposition where the Cd/S weight percentage ratio was changed with nature of substrates. The direct energy band gap was observed in the 1.63–2.50 eV range for the films grown on different substrates. The investigated properties of thin CdS layers demonstrated that the selection of substrate(in terms of nature) during device fabrication plays a crucial role.     

Tunable photoluminescence of poly(phenylene vinylene) nanofibers by doping of semiconductor quantum dots and polymer

In this paper, we report the effects of polyvinyl alcohol (PVA) and CdS quantum dots (QDs) on the photoluminescence (PL) properties of poly(phenylene vinylene) (PPV) nanofibers. The composite nanofibers were fabricated by coupling self-assembly and electrospinning method. A significant blue shift in both PL spectra and fluorescence images of PPV fibers was observed after doping of CdS QDs and PVA in succession. It was found that the changes in PL spectra of PPV originated from the chemical interactions between PPV and PVA, and the changes in the crystallization of PPV itself. A possible PL mechanism was proposed accordingly.     

Cascade structure of TiO2/ZnO/CdS film for quantum dot sensitized solar cells

Quantum dot sensitized solar cells based on cascade structure of TiO₂/ZnO/CdS electrode and polysulfide electrolyte were fabricated. The ZnO layer was deposited on screen-printed TiO₂ layer by ultrasonic spray pyrolysis method. The structure, morphology and impedance of TiO₂/ZnO film photoanode and the photovoltaic performance of TiO₂/ZnO/CdS cell were investigated. It is found that the short circuit current density and conversion efficiency are significantly improved by the introduction of ZnO layer into TiO₂/CdS film. A power conversion efficiency of about 1.56% has been obtained for TiO₂/ZnO/CdS cell, which is about 57% higher than that for TiO₂/CdS cell (0.99%). The formation of an inherent energy barrier between TiO₂ and CdS films and the passivation of surface traps on the TiO₂ film caused by the introduction of ZnO layer, which reduces the charge recombination and favors the electron transport, should be mainly responsible for the performance enhancement of TiO₂/ZnO/CdS cell.     

硅基ZnO纳米棒阵列异质结太阳能电池的水热合成及其光伏性能

通过低温水热法,在图案化的p型硅衬底上合成氧化锌（ZnO）纳米棒阵列薄膜,制备出具有p-Si/n-ZnO纳米棒（NR）阵列结构的异质结太阳能电池（HSCs）。通过直流磁控溅射技术,分别在前后面板溅射沉积ITO和Al膜接触电极层。研究ZnO籽晶层的退火温度、ZnO纳米棒阵列水热合成的时间等因素对ZnO纳米棒阵列的晶体结构、表面形貌和光学性能的影响。p-Si/n-ZnO纳米棒阵列HSCs的最佳短路电流密度和总能量转换效率分别为11.475 mA·cm^-2和2.0%。相比p-Si/n-ZnO薄膜HSCs,p-Si/n-ZnO纳米棒阵列HSCs的光伏性能得到了有效提高。     

Enhanced electroluminescence from MEH-PPV-POSS:CuInS2 nanocomposite based organic light emitting diode

Polymer:quantum dot (QD) composites show enhanced optical and electronic properties. In this study, polymer light-emitting diodes (PLEDs) were fabricated and characterized using poly[2-methoxy-5-(2-ethyl-hexyloxy)-1,4-phenylenevinylene] end capped with polyhedral oligomeric silsesquioxanes (MEH-PPV-POSS) as a luminescent polymer host and copper indium disulfide (CuInS₂) QDs as a dopant. The emitted light originates from MEH-PPV-POSS. Incorporation of CuInS₂ QDs into polymer matrix until certain amounts improved the device performance in terms of electroluminescence (EL) intensity, luminance, current and power efficiency compared to that of the undopped device. The improvement is remarkable when the QD concentration is 0.3 wt% in the composite. We demonstrate that CuInS₂ QDs provide a better balance of charge carriers and prevent the formation of polymeric aggregates.     

A NEW CONCEPT TOWARD INDUSTRIALIZATION OF Cu-III-VI_2 THIN FILM SOLAR CELLS AND SOME PRELIMINARY EXPERIMENT RESULTS

1.IntroductionA fterm ore than tw o decades'extensive w ork,the ultim ate solutionsusing thin film solarcellsforterrestrialapplicationshave em erged m oredefinitely.Itisgenerally believed thatthe PV m odulesm adeofa-Si:H w illdom inate thecurrentm arketso…     

A NEW CONCEPT TOWARD INDUSTRIALIZATION OF Cu-Ⅲ-Ⅳ2 THIN FILM SOLAR CELLS AND SOME PRELIMINARY EXPERIMENT RESULTS

A new concept of full vacuum manufacturing for Cu-Ⅲ-Ⅳ2 thin-film solar cells has been discussed Cu-Ⅲ-Ⅳ2 thin-film solar cells manufactured using full in-line reactive sputtering will result in lower cost than that of the conventional method with CdS layer fabricated with chemical bath deposition (CBS) method. Using reactive sputtering process with organometallic gases, the compositions and electronic properties of Cu-Ⅲ-Ⅳ2 thin-film can be fine-tuned and precisely controlled, n-type Cu-Ⅲ-Ⅳ2 film and ZnS suffer layer can also be deposited using the in-line sputtering instead of using the CdS layer. The environmental pollution problems arising from using CdS can be eliminated and the ultimate goal of full in-line process development can then be realized. Some preliminary experimental results on a modal solar cell fabricated by the new technique in the new concept have been presented.     

A NEW CONCEPT TOWARD INDUSTRIALIZATION OF Cu-Ⅲ-Ⅵ2 THIN FILM SOLAR CELLS AND SOME PRELIMINARY EXPERIMENT RESULTS

A new concept of full vacuum manufacturing for Cu-Ⅲ-Ⅳ2 thin-film solar cells has been discussed. Cu-Ⅲ-Ⅳ2 thin-film solar cells manufactured using full in-line reactive sputtering will result in lower cost than that of the conventional method with CdS layer fabricated with chemical bath deposition (CBS) method. Using reactive sputtering process with organometallic gases, the compositions and electronic properties of Cu-Ⅲ-Ⅳ2 thin-film can be fine-tuned and precisely controlled. n-type Cu-Ⅲ-Ⅳ2 film and ZnS suffer layer can also be deposited using the in-line sputtering instead of using the CdS layer. The environmental pollution problems arising from using CdS can be eliminated and the ultimate goal of full in-line process development can then be realized. Some preliminary experimental results on a modal solar cell fabricated by the new technique in the new concept have been presented.     

Ag-TiO2纳米棒阵列的抗菌性和光催化性能研究

目的：制备一种高抗菌性和高光催化活性的Ag掺杂TiO2（Ag-TiO2）纳米棒阵列。方法通过磁控溅射与水热复合处理法,在钛箔片表面制备出Ag掺杂TiO2（Ag-TiO2）纳米棒阵列,酸化处理过的试样在500℃下煅烧2 h。采用X射线衍射（XRD）进行物相分析,利用场发射扫描电子显微镜（SEM）、场发射透射电子显微镜（TEM）、能量分散谱仪(EDS)观察试样的表面、截面形貌、微观结构和组成,并探究其对大肠杆菌和金黄色葡萄球菌的杀菌性能和对亚甲基蓝的光催化降解能力。结果该工艺下制备的 Ag-TiO2纳米棒大小均匀,取向明显,主要由锐钛矿型 TiO2相组成。Ag-TiO2纳米棒对大肠杆菌和金黄色葡萄球菌具有优异的杀菌效果,杀菌率几乎达到100%。Ag-TiO2纳米棒能有效地提高亚甲基蓝的降解率。结论磁控溅射与水热复合处理法在钛箔片表面成功制备出Ag-TiO2纳米棒阵列,此阵列具有优异的杀菌能力、高抗菌和光催化降解性能。     

Growth mechanism of CdS film prepared by chemical bath deposition

In this paper, sodium citrate was adopted as a complexing agent and ammonia merely served as pH adjustor to investigate the growth mechanism of CdS film The growth rate, structural properties, surface morphology microstructure, and optical properties of CdS films were studied by profilometer, X-ray diffractometer（XRD）scanning electron microscopy（SEM）, transmission elec tron microscopy（TEM）, and spectrophotometer, respec tively. The SEM images show that CdS films prepared with higher ammonia concentration have lower nucleation density on substrate. SEM and EDS results show that the formation of Cd（OH）2is not required in the growth of CdS film. As the ammonia concentration increases, the sites tha previously adsorbed S2-are taken by OH-which leads to lower S2-density on substrate. CdS film forms through direct reaction of Cd2？with the S2-which are adsorbed on the substrate. Lower S2-density on the substrate results in the decrease of particle density on the substrate. The as deposited CdS films have relatively high-average trans mittance（＊80 %） in the wavelength range from 500 to1,000 nm which makes them suitable to be used in sola cell.     

Fabrication of highly oriented ZnO nanorod arrays by galvanostatic deposition

Highly oriented ZnO nanorod arrays were suecessfully prepared on the indium tin oxide (ITO) substrate using a galvanostatic electrodeposition method.The ITO substrate was pretreated with ZnO nanoparticles via simple low-temperature solution route.The crystallinity,microstructure of surface,and optical properties of the obtained ZnO were characterized by X-ray diffraction,scanning electron microscope,and transmittance spectrum.The results indicate that the average diameter of ZnO nanorod arrays is about 30 nm,and the narrow size distribution ranges from 20 to 50 nm The nanorod arrays are growing along [001] direction with an orientation perpendicular to the substrate.When the wavelength of incident is over 380 nm,the ZnO nanorod arrays show a high optical transmission of above 95%.Furthermore,the possible growth mechanism of the nanorod arrays was discussed.     

Synthesis,characterization and spectroscopic studies of CdS/polyaniline core/shell nanocomposite

In this work, CdS/polyaniline (PANI) nanocomposite was synthesized by a novel method. Transmission electron microscope (TEM) images showed that the CdS/PANI nanocomposite had a core/shell structure. The crystal structure was studied using X-ray diffraction (XRD) and the obtained results showed that CdS had cubic structure. Fourier transform infrared (FTIR) spectroscopic measurements confirmed the formation of PANI at the surface of CdS nanoparticle. The prepared samples were further characterized using UV–visible (UV–vis) and fluorescence spectroscopy.     

Effect of polyethyleneimine on the growth of ZnO nanorod arrays and their application in dye-sensitized solar cells

A series of oriented hexagonal wurtzite ZnO nanorod-array films were grown on fluorine-doped tin oxide (FTO) coated glass substrates by chemical process. The effect of polyethyleneimine (PEI) on the structure and micro-morphology of ZnO nanorod array films, as well as the photoelectric conversion properties in dye-sensitized solar cells (DSSCs) was analyzed. It was found that with the addition of PEI in growth solution, the ZnO nanorods became smaller in diameter and longer in length and hence the dye absorption and the photovoltaic performance of DSSCs were improved. A power conversion efficiency of 2.30% had been achieved on a DSSC based on a 7.9 μm-long nanorod array film prepared by a growth solution containing the PEI.     

The photovoltaic performance of new ruthenium complexes in DSSCs based on nanorod ZnO electrode

Three new heteroleptic ruthenium complexes, [Ru(L1)(dcbpy)(NCS)₂] Ru^II(4,7-diphenyl-1,10-phenanthroline-disulfonic acid disodium salt)(4,4′-dicarboxy-2,2′-bipyridyl)-di(thiocyanate) [K28], [Ru^II(L1)₂(NCS)₂] Ru^IIbis(4,7-diphenyl-1,10-phenanthroline-disulfonic acid disodium salt)-di(thiocyanate) [K313], and [Ru(L2)(dcbpy)(NCS)₂] Ru^II(1,10-phenanthroline-5,6-dione)(4,4′-dicarboxy-2,2′-bipyridyl)-di(thiocyanate) [K27], have been synthesized as sensitizers for dye-sensitized solar cells (DSSCs) using ZnO nanorod electrode. The photovoltaic performances of the solar cells based on these sensitizer dyes are studied under AM 1.5 irradiation (100 mW/cm²). Their photophysical and electrochemical properties are also investigated. ZnO nanorod based dye sensitized solar cell sensitized with K28 ruthenium complex bearing bulky sulfoxy groups gives an overall conversion efficiency of 2.51, a short-circuit current of 7.19 mA/cm², and an open circuit voltage of 550 mV. K28 is firstly designed and synthesized in the literature to increase molar extinction coefficients and enhanced spectral response in the visible light by expanding the π-conjugation, and of course to reduce back electron transfer due to the bulky sulfoxy groups. The vertical excitation energies, corresponding excitation wavelengths and oscillator strengths, predominant orbitals involved in ten singlet–singlet transitions and their characters obtained from the single point TD-DFT calculations have been obtained for K28.     

Solution-based synthesis of ZnO nanoparticle/CdS nanowire heterostructure

The heterostructure of ZnO nanoparticle (NP)/CdS nanowire (NW) was successfully fabricated by a two-step chemical solution method. The first, CdS nanowires were synthesized by a simple solvothermal route. The second, ZnO nanoparticles were grown on the surface of CdS nanowires in a chemical solution of Zn(CH₃COO)₂·2H₂O and anhydrous ethanol at 200 °C. The heterostructure of synthesized ZnO NP/CdS NW was characterized by transmission electron microscopy (TEM). The effects of reaction conditions, such as different reaction time of CdS nanowires synthesized and deposition reaction time were investigated. Moreover, the formation mechanism of the ZnO NP/CdS NW heterostructure has been phenomenologically discussed.     

微波水热法制备分等级空心球状CdS纳米结构(英文)

以氯化镉和硫代硫酸钠为原料,以乙二胺四乙酸(EDTA)为模板剂,采用微波水热(M-H)法成功制备了空心球状 CdS 纳米结构。采用 X 射线衍射仪(XRD)、场发射扫描电子显微镜(FE-SEM)、能量弥散X射线谱(EDS)和高分辨透射电子显微镜(HRTEM)对所制备的CdS 纳米结构进行表征。采用紫外-可见吸收光谱研究所制备的分等级空心球状 CdS 纳米结构的光学性能。结果表明:得到的CdS是具有纤锌矿结构的直径为 400～600nm的分等级空心球状纳米结构,这种结构由30nm左右的纳米颗粒自组装构成。EDTA和微波辐射在分等级空心球状 CdS纳米结构的形成过程中起了重要作用,讨论了这种作用并提出可能的生长机理。所制备的分等级空心球状CdS纳米结构具有较好的蓝光发射性能。