Effects of hole injection layer thickness on the luminescent properties of white organic light-emitting diodes

This work investigates how the thickness of the hole injection layer (HIL) influences the luminescent characteristics of white organic light-emitting diodes (WOLED). Experimental results indicate that inserting a thin HIL (<200 Å) into a WOLED without an HIL reduces the brightness and clearly changes the chromaticity because the surface of the 4,4′,4″-tris{N,-(3-methylphenyl)-N-phenylamino}-triphenylamine) (m-MTDATA) film is extremely rough. In contrast, a dense film structure and the fine surface morphology of m-MTDATA of moderate thickness (350-650 Å) provides a uniform conducting path on which holes cross the indium tin oxide (ITO)/HIL interface, improving luminescent performance, associated with the relatively stable purity of the color of the emission, with Commission Internationale 1′Eclairage (CIE) coordinates of (x = 0.40, y = 0.40). However, inserting a thick HIL (>650 Å) reduces the luminescent performance and causes red-shift, because the holes and electrons in the effective emissive confinement region become less optimally balanced. Moreover, optimizing the device structure enables a bright WOLED with CIE coordinates of (x = 0.34, y = 0.33) to reach a luminance of 7685 cd/m² at a current density of 100 mA/cm², with a maximum luminous efficiency of 1.72 lm/W at 5.5 V.     

Triangular pattern formation on silicon through self-organization of GaN nanoparticles

Nanoparticles of gallium nitride, synthesized by a low-temperature reaction between triethyl gallium and ammonia, were introduced onto silicon wafers containing a thin layer of chemically prepared silicon dioxide. At room temperature, the nanoparticles form unstructured agglomerates on the surface. However, upon annealing the samples beyond the decomposition temperature of the silicon dioxide layer, the gallium nitride particles self-organize to form triangular structures. The pattern formation is attributed to the domain separation associated with the (1 × 1)-(7 × 7) surface phase transformation followed by selective incorporation of the nanoparticles.     

Detection and Quantifiable Evaluation of Copper(II) Ions through Luminescent Sensing between Two Homologous Metal‐organic Frameworks

Two luminescent metal‐organic frameworks (LMOFs), namely, [Cd₂(DDCPB) · (DMF)₂ · H₂O]_n (CHD‐ 1 ) and [Zn₂(DDCPB) · (DMA)₂]_n · n(DMA) (CHD‐ 2 ), were solvothermally constructed, which present structural diversity. Single crystal X‐ray diffraction analysis indicates that they consist of [Cd₂(μ2‐O)₂(κ‐O)₂] building units (for CHD‐ 1 ), [Zn₂(κ‐O)₆] building units (for CHD‐ 2 ), which are further linked by multicarboxylate H₄DDCPB to construct microporous frameworks. Remarkably, both CHD‐ 1 and 2 exhibit highly efficient luminescent sensing for environmentally relevant Cu²⁺ ions through luminescence quenching. Theoretical and experimental calculations indicate that the luminescent quenching can be attributes to the donor‐acceptor electron transfer between the MOFs and analytes. This work indicates that CHD‐ 1 and 2 could be taken as a potential candidate for developing multifunctional luminescence sensors.     

稀土碘化物的合成及其发光性质的研究

本文将纯稀土金属与碘化汞在加温下合成了钪、镝、铒和铥的碘化物。并用DTA方法测定了NaI-ScI_3,NaI-DyI_3,NaI-ErI_3和NaI-TmI_3二元体系的相图,它们都是简单的有低共熔点的二元体系,但是后面三个体系在固相有相变,可能是形成了不稳定的化合物。文中还制造了填充不同比例的碘化钠和稀土金属碘化物混合物的金属卤化物灯,将它们的发光特性与汞灯进行了比较。碘化钠和稀土金属碘化物的加入能明显地改善灯的色温,显色性和光效。     

含Eu(DBM)_3·H_2O纳米微晶的光学树脂的制备及性能研究

稀土β二酮的配合物因其具有Antenna效应,发光强度明显增强;而且它的激光性质也被证实[1] ,是应用价值极大的配合物.稀土配合物与高分子的复合,获得了兼具二者优良性能的功能材料,有很好的应用前景.通常二者的复合多采用直接掺杂、机械共混和熔融等方法.但由于二者的相容性较差,并且存在着浓度淬灭现象,使获得高稀土含量、分散均匀的聚合物发光材料非常困难.以往,杨柏小组分别采用直接掺杂和原位复合的方法制备了含稀土配合物的光学树脂[2 ,3 ] ,但稀土配合物含量受到限制.本文在文献[4,5 ]的基础上,采用化学沉淀的方法,制备了30～30 0nmEu…     

Preparation and time-gated luminescence bioimaging application of ruthenium complex covalently bound silica nanoparticles

Luminescent ruthenium(II) complex covalently bound silica nanoparticles have been prepared and used as a probe for time-gated luminescence bioimaging. The new nanoparticles were prepared by copolymerization of a luminescent Ru(II) complex tris(5-amino-1,10-phenanthroline)ruthenium(II) conjugated with 3-aminopropyl(triethoxy)silane (APS-Ru conjugate), free (3-aminopropyl)triethoxysilane (APS) and tetraethyl orthosilicate (TEOS) in a water-in-oil reverse microemulsion consisting of Triton X-100, n-octanol, cyclohexane and water in the presence of aqueous ammonia. Characterization by transmission electron microscopy indicates that the nanoparticles are monodisperse, spherical and uniform in size, 64 ± 4 nm in diameter. Compared with the dye-doping nanoparticles, dye leakage of the new nanoparticles was remarkably decreased. In addition, it was found that the Ru(II) complex luminescence could be effectively enhanced with a longer luminescence lifetime (∼2.3 μs) after forming the nanoparticles, which enables the nanoparticles to be suitable as a bioprobe for time-gated luminescence bioimaging applications. The nanoparticle-labeled streptavidin was prepared and successfully used for time-gated luminescence imaging detection of an environmental pathogen, Giardia lamblia, with high specificity and sensitivity.     

Two Cd(II) complexes derived from mercapto-triazole ligands: syntheses,crystal structures,and luminescent properties

Two cadmium complexes, {[Cd(a-ptt)(ptt)]·H₂O} _n (1) and [Cd(a-Hmtt)₂(SO₄)H₂O]·CH₃OH (2), have been prepared based on 4-amino-3-(4-pyridine)-5-mercapto-1,2,4-triazole (a-Hptt) and 4-amino-3-methyl-5-mercapto-1,2,4-triazole (a-Hmtt), respectively. In 1, amino-triazole ligand a-Hptt can partly be deaminated and transformed into 3-(4-pyridine)-5-mercapto-triazole (Hptt) under hydrothermal conditions. X-ray diffraction analysis reveals that 1 exhibits an unusual 2-D lampshade-type layer structure in which the amino ligand a-ptt and the deamination ligand ptt display exo-tridentate bridging and bidentate bridging, respectively. Complex 2 is mononuclear and further assembled into a 3-D supramolecular architecture via non-covalent interactions. Complexes 1 and 2 were characterized by elemental analyses, IR, and thermogravimetric analyses. Furthermore, solid-state luminescent properties of 1 and 2 have also been investigated.     

N,N-B螯合物光物理性质的密度泛函理论研究

采用密度泛函理论(DFT)和含时密度泛函理论(TD-DFT)方法计算了4种N,N-B螯合物1,1q,2和2q的基态和激发态结构、吸收和发射光谱、跃迁密度矩阵、分子内电荷转移特征、黄昆(HR)因子、FranckCondon因子和电子耦合等光物理性质,深入探究化合物1q和2q在几何结构微调后发光效率降低的本质原因.计算结果表明,N,N-B螯合物中喹啉取代吡啶,以及吲哚配体中N杂原子的引入对光物理性质产生了较大影响.相比于化合物1和2,化合物1q和2q由于共轭面的扩展导致HOMO-LUMO能隙变窄,使吸收红移.通过计算HR因子和跃迁密度矩阵对激发态的特征和几何弛豫进行分析,结果表明化合物1q和2q具有明显增强的片段间电荷转移特征,发射能和振子强度减弱导致kr减小,并且激发态和基态间的电子耦合急剧增强造成快速的非辐射衰变,导致化合物1q和2q在CH2Cl2溶液中不发光.同时,化合物1和2具有高效的发光效率和较大的斯托克斯位移,是一类有发展前景的发光材料.     

Coupled Strain and Fresnel Response of Photoelastic Coatings at Oblique Incidence

This paper presents a theoretical model and corresponding experimental results of the oblique-incidence response of a luminescent photoelastic coating (LPC). LPCs use a luminescent dye that both partially preserves the stress-modified polarization state and provides high emission signal strength at oblique surface orientations. These characteristics enable the technique to acquire full-field strain separated measurements and principal strain directions, potentially on complex three-dimensional geometries, without the use of supplemental experimental or analytical techniques. Results of a single-layer LPC on a disk in diametral compression are presented to assess a theoretical model and evaluate the measurement sensitivity.

Preparation and characterization of a novel luminescent nanoparticles

In this paper, a new kind of fluorescent nanomaterial with morin modified alumina core and silica shell was prepared. Samples were characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), photoluminescent (PL) spectroscopy and fluorescence microscope. TEM results indicated that this material could be synthesized in nanometer range. PL spectra suggested that this new synthesized material was photostable and it showed nearly no dye leakage. This was because the dye molecules could form stable complex with the reactive aluminum cations on the surfaces of the alumina particles. The excitation and emission maxima of this new luminescent material were located at 420 and 493 nm, respectively. This new kind of luminescent nanomaterial was prepared by morin, AlCl₃ and tetraethyl orthosilicate, which was very important for the large-scale and economic preparation luminescent nanoparticles because these precursors were inexpensive and the preparation process was convenient.