Tuning of Optical Properties via Annealing of Bismuth Ferrite (BiFeO3) Thin Films

In this study we are reporting annealing induced optical properties of bismuth ferrite (BiFeO3) thin films deposited on glass substrate via spin coating at 5000 rpm. The structural, optical and surface morphology of BiFeO3 (BFO) thin films have been studied via X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Optical absorption (UV-Vis) and Photoluminescence (PL) spectroscopy. XRD spectra confirm annealing induced phase formation of BiFeO3 possessing a rhombohedral R3c structure. The films are dense and without cracks, although the presence of porosity in BFO/glass was observed. Moreover, optical absorption spectra indicate annealing induced effect on the energy band structure in comparison to pristine BiFeO3. It is observed that annealing effect shows an intense shift in the UV-Vis spectra as diffuse absorption together with the variation in the optical band gap. The evaluated optical band gap values are approximately equal to the bulk band gap value of BiFeO3.

Hybrid Luminescent Films Obtained by Covalent Anchoring Terbium Complex to Silica-based Network

New monomer N-(4-carboxyphenyl)-NL-(propyltriethoxysilyl)urea (1) which acts as both a ligand for Th3+ ion and a sol-gel precursor has been synthesized and characterized by H-1 NMR, and MS. Hybrid luminescent thin films consisting of organoterbium covalently bonded to a silica-based network have been obtained in situ via a sol-gel approach. Strong line emission of Tb3+ ion was observed from the hybrid luminescent films under UV excitation.

Brightness of Blue/Violet Luminescent Nano-Crystalline AZO and IZO Thin Films with Effect of Layer Number:For High Optical Performance

From different reports, it （AZO） and indium-doped including usage areas. We nanocrystalline films with is realized that there is a need to consider all sides of aluminum-doped zinc oxide zinc oxide （IZO） thin films with their optical, luminescence and surface properties establish an assessment to carry out further information to summarize AZO and IZO impact of the layer number.

Luminescent Properties of Europium Complexes with Different Long Chains in Langmuir-Blodgett (LB) Films

A series of europium(III) complexes with different chain length, tris [2-m-pyridylmethanamido-5-phenyl- (1,3,4)-oxadiazole] mono [2-(4-n-alkylphenyl)-iminazole (4,5-f)-1,10-phenanthroline] Eu(III) [Eu(PMA)3Nn (n = 6, 10, 14,18)] were synthesized. All of these amphiphilic europium(III) complexes could form stable Langmuir film at air/water interface and could be transferred onto hydrophilic quartz and mica substrates by measurement of UV spectra in which the absorbance of the LB films at about 288 nm scales showed the linearity with the number of layers deposited. In order to investigate relation between fluorescence properties and the arrangement of molecular in LB films, surface topography of monolayer films were observed by atomic force microscopy (AFM). Results showed that the emission spectra have Eu(III) characteristic peaks and strong emission strength. It is interesting that the molecular with looser arrangement in LB films has better monochromacity, which illustrated that energy might transferred more easily from ligand to Eu(III) in loosen structure films.

Luminescence Properties of Tb^(3+)-Doped LuAG Films Prepared by Pechini Sol-Gel Method

Lu3Al5O12（LuAG） thin films with different Tb^3＋ concentration were prepared on carefully cleaned （111 ） silicon wafer by a Peehini process and dip-coating technique. Heat treatment was performed in the temperature range from 800 to 1100 ℃. The crystal structure was analyzed by XRD. The results show that LuAG film starts to crystallize at about 900 ℃, and the particle size increases with the sintering temperature. Excitation and emission spectra of Tb^3＋ doped LuAG films were measured. The effects of heat-treatment temperature and doping concentration of Th3 ＋ on the luminescent properties were also investigated. For a comparison study, Th^3＋-doped LuAG powders were also prepared by the same sol-gel method.

Analytical Expression of Relaxation Luminescence in ZnS:Er^(3+)Thin Films

The relaxation luminescence of ZnS:Er 3+ thin films is studied with luminescence dynamics model. The excitation and emission processes of Er 3+ in ZnS host are described through the resonant energy transfer method. Taking the energy storing effect of the traps into account, an expression is obtained by using the convolution formula, which may describe luminescence decay process containing the multiple relaxation luminescence peaks. The experimental results confirm that the relaxation characteristics of the electroluminescence are related to the carriers captured by the bulk traps.

Structural, Optical and Luminescence Properties of ZnO Thin Films Prepared by Sol-Gel Spin-Coating Method： Effect of Precursor Concentration

Transparent zinc oxide（ZnO） thin films are fabricated by a simple sol-gel spin-coating technique on glass substrates with different solution concentrations（0.3-1.2 M） using zinc acetate dehydrate [Zn（CH_3COO）_2·2H_2O] as precursor and isopropanol and monoethanolamine（MEA） as solvent and stabilizer, respectively. The molar ratio of zinc acetate dehydrate to MEA is 1.0. X-ray diffraction, ultraviolet-visible spectroscopy and photoluminescence spectroscopy are employed to investigate the effect of solution concentration on the structural and optical properties of the ZnO thin films. The obtained results of all thin films are discussed in detail and are compared with other experimental data.

Correlation between the Low-Temperature Photoluminescence Spectra and Photovoltaic Properties of Thin Polycrystalline CdTe Films

A dominant intrinsic luminescence band, which is due to the surface potential barriers of crystalline grains, and an edge doublet, which arises as an LO-phonon repetition of the e-h band, has been revealed in the low-temperature photoluminescence spectra of fine-grained obliquely deposited films. Doping film with In impurity leads to quenching of the doublet band, while further thermal treatment causes activation of the intrinsic band, the half-width and the blue shift of the red edge of which correlates with the maximum value of anomalously high photovoltage generated by the film.

Luminescent Thin Film of Doped Terbium Complex Obtained by Sol-Gel Method

The transparent luminescent thin films of doped terbium complex were obtained by sol gel method. The result indicates that rare earth carboxylates with poor solubility can be homogeneously doped into sol matrix in situ. The fluorescence spectra show that the thin film material emits the characteristic narrow band emission of Tb 3+ under the UV excitation.

Preparation and Luminescence Properties of LB Films Based on 4-Hexadecyloxybenzoic Terbium

LB films of 4 hexadecyloxybenzoic terbium by using the subphase containing Tb 3+ were prepared. The monolayer behavior of 4 hexadecyloxybenzoic acid (HOBA) on the subphase containing rare earth ions was studied. IR and UV spectra show that the rare earth ions were bound to carboxylic acid head groups and the coordination took place between the polar head group and the rare earth ions. The luminescence spectra show that the LB films have the fine luminescence properties, and the LB films emit strong luminescence under UV light irradiation.

CHARACTERIZATION AND LUMINESCENCE PROPERTIES OF THE DYE-DOPED POLYMER LANGMUIR-BLODGETT FILMS

1,1,4,4-Tetraphenyl-1,3-butadiene (TPB) was successfully introduced into the polymer multilayer films by means of Langmuir-Blodgett (LB) technique. Results of UV-VIS spectra and X-ray diffraction showed that the uniform films had a layer structure similar to the superlattice of organic multiple quantum wells. The electroluminescence (EL) devices fabricated from the doped polymer LB films emitted blue light. Compared with the casting films, the photoluminescence (PL) and EL spectra showed that the exciton energy shifts to higher and the half-width of the emission peak becomes narrower due to exciton confinement effect.

In-Situ Composition and Luminescence of Europium and Terbium Coordination Polymers/PEMA Hybrid Thick Films

Europium and terbium coordination polymers of pyridine-3-carboxylic acid were in-situ composed with ethyt methacrylate （ EMA ）. With the polymerization of EMA monomer and the formation of europium and terbium coordination polymers of pyridiae- 3-carboxylic acid, the transparent hybrid thick fihns composed of [ Eu（ NIC ）3 ]n （ [ Tb（ NIC）3 ]n ） and poly ethyl mettuwrylate （ PEMA ） have been prepared. The luminescence properties and energy transfer of these polymeric composites were studied with absorption spectra, fluorescent excitation trod emission spectra in detail. All the hybrid thick films composed of terbium coordination polymer show the characteristic strong green emission of terbium ions, which implies the same energy transfer mechanism as the pure complex and the hybrid composite film is a suitable sabstrate for the luminescence of terbium ions. In the range of camposing concentration of luminescent species （0.01,0.025,0.05,0.1 mmol /15 mL EMA ）, emission intensities increase with the increasing of corresponding composing concentration and the concentration quenching effect does not take place.

Structure and Photoluminescence of Polycrystalline MgxZn1-xO Films

Different photoluminescence （PL） spectra are observed for rf magnetron sputtered polycrystalline Mg0.25Zn0.75O and Mg0.37Zn0.63O films on silicon substrates when excited by different wavelengths. When the excitation wavelength is 280nm, a UV emission peak at 370nm and a blue peak at 462nm are generated for the Mg0.25Zn0.75O film, and those two peaks for the Mg0.37Zn0.63O film shift to 366nm and 466nm, respectively. The wavelengths of the PL peaks are related to the excitation wavelength. The stronger peak is obtained in the blue band due to a large number of oxygen vacancies caused by excess Zn and Mg atoms, while the weaker peak is obtained in the ultraviolet band.

Er^(3+) Doped BaTiO_3 Optical-Waveguide Thin Films Elaborated by Sol-Gel Method

Erbium doped BaTiO 3 optical-waveguide films on Pyrex substrate was elaborated successfully through sol-gel method. BaTiO 3 is well crystallized when the film is annealed at 650 ℃ in air circumstance. The so-prepared films with 13 layers have comparatively lower refractive index than bulk BaTiO 3, and it can support two TM and TE modes. Photoluminescence and up-conversion luminescence spectra proved the successful doping of rare earth ions.

Assembly and Characterization of Rare-earth-containing Polyoxometalate [Eu(P_2Mo_(17)O_(61))_2]^(17-) and Poly(allylamine hydrochloride) Multilayer Films

The ultrathin multilayer films of rare-earth-containing polyoxometalate cluster K_ 17[Eu(P_2Mo_ 17O_ 61)_2] (EuPMo) and poly(allylamine hydrochloride)(PAH) have been prepared by the Layer-by-Layer(LbL) self-assembly method. The photoluminescent behavior of the films investigated at room temperature shows the Eu 3+ characteristic emission pattern of 5D_0→ 7F_J(J=1—4). The occurrence of the photoluminescent activity confirms the potential of creating luminescent multilayer films with polyoxometalates(POMs).

Structural, Morphological and Optical Properties of ZnO Thin Films Grown on γ-LiA1O_2 Substrate by Pulsed Laser Deposition

ZnO thin films were deposited on the substrates of （100） γ-LiAlO2 at 400,550 and 700℃ using pulsed laser deposition （PLD） with the fixed oxygen pressure of 20 Pa, respectively. When the substrate temperature is 400℃, the grain size of the film is less than 1μm observed by Leitz microscope and measured by X-ray diffraction （XRD）. As the substrate temperature increases to 550℃, highly-preferred c-orientation and high-quality ZnO film can be attained.While the substrate temperature rises to 700℃, more defects appears on the surface of film and the ZnO films become polycrystalline again possibly because more Li of the substrate diffused into the ZnO film at high substrate temperature. The photoluminescence （PL） spectra of ZnO films at room temperature show the blue emission peaks centered at 430 nm. We suggest that the blue emission corresponds to the electron transition from the level of interstitial Zn to the valence band. Meanwhile, the films grown on γ-LiAl02 （LAO） exhibit green emission centered at 540 nm, which seemed to be ascribed to excess zinc and/or oxygen vacancy in the ZnO films caused by diffusion of Li from the substrates into the films during the deposition.

Synthesis of RE-Ag,Al-RE-doped sol-gel glass and films for solar cells

The paper dealt with the study of fluorescence properties of sol-gel systems doped with rate-earth ions and co-doped with silver. The general problem for these types of inorganic phosphors was a very low absorbance in the visible range. Therefore, a sensitizer of luminescence of the rare-earth ions should be selected and used. The sensitizer should possess a good absorbance in the visible range and strong interaction with the rare-earth ions. In this study silver ions were selected as the sensitizer.

PHOTOSTIMULATED LUMINESCENCE ON BaFCl: Eu^(2+) THIN FILM

In this paper, we have succesfully prepared the sample of BaFCl: Eu2+thin film using the vacuum thermal evaporation method and first studied photostimulated luminescence on BaFCl: Eu2+thin film.

高湿度下具有荧光指示功能的PET复合膜的制备与性能

为了制备出能在高湿度、易结雾环境下可持续发光的薄膜,以聚对苯二甲酸乙二醇酯(PET)膜为基底,将具有优异疏水功能的新型稀土发光配合物和聚甲基丙烯酸甲酯(PMMA)均匀分散制成发光涂覆液,通过涂覆刮膜技术,制备出PET-PMMA发光复合膜,并对其进行测试表征。荧光分光光度计和共聚焦显微镜测试的结果表明:发光材料占聚合物PMMA的质量分数为1.50%时所制备的PET发光膜具有良好的表面均匀性和最佳的荧光性能,荧光强度可达到9979 a.u.,在不同激发波长下PET-PMMA发光复合膜均可以显现出发光材料中Eu3+的特征荧光发射峰;测得发光复合膜的最佳紫外激发波长为350 nm,在最佳激发波长下发光复合膜具有较好的色纯度;通过对比发光复合膜浸泡在水溶液7 d内每天的荧光强度值,发现在发光材料仅有1.50%的前提下,样品的荧光强度损失仅有5%,这表明所制备的发光复合膜遇水易猝灭的弊端得到极大改善,这为PET农膜在潮湿、易结雾环境下实现长期稳定的荧光指示功能提供了重要基础。