Anti-Stokes Bands of Intrinsic Radiation in Undoped GaAs Crystals

It has been established that undoped gallium crystals exhibit anti-Stokes radiation with energy corresponding to the interband recombination of these crystals. Its appearance is most probably determined by EL2 defects, and its intensity depends on the product of the cross sections for photoionization of electrons and the holes from these defects.     

Bright Blue Light—emitting Diodes Based on a Novel Fluorescent Dye Containing Heterocyclic Groups

Novel molecular material ,1-benzothiazoly-3-pheny1-pyrazoline (BTPP) was found to function as bright blue light emitting dye in organic electroluminescent device, and its optical and electric characteristics were investigated. This heterovyclic compound exhibited good characteristics of blue photoluminescence and electroluminescence,which had the emission peak at 450nm .The single layer light-emitting devices using BTPP as light -emitting material dispersed in poly(N-vinylcarbazole)(PVK) and double layer ones using PBD as hole block layer above the light-emitting layer were fabricated using conventional spin-casting and vaccum vapour deposition methods. The introduction of PBD has enhanced electron injection and luminance efficiency, compared with the single layer LEDs.     

Accurate measurement of capture cross sections in deep level transient spectroscopy: Application to EL2 in GaAs

A rigorous formulation of capacitance changes during trap filling processes is presented and used to accurately determine the electron capture cross section of EL2 in GaAs at a particular temperature, 377K, in this case. The value, σ_n (377K) = 2.7 × 10⁻¹⁶ cm², is compared with that predicted from the emission dependence.     

无机电致发光平板显示技术研究进展

无机电致发光（EL）平板显示是一项有着广泛应用前景的自发光型平板显示技术。本文简单介绍了无机EL平板显示器的结构、原理和实现全彩色显示的方法，阐述了所使用的电极、介质和发光材料的作用、要求及研究现状，分析了存在的问题，并展望了其产业化的前景。     

NARROW BANDWIDTH BRIGHT SCARLET ORGANIC ELECTROLUMINESCENT DEVICE BASED ON N,N'-BIS[4-(N,N-DIMETHYLAMONO)-BENZYLIDENE]-DIAMINOMALEONITRILE DYE

A novel red dye, N, N'-bis[4-(N,N-dimethylamino)-benzylidene]diaminomaleonitrile (BAM), was prepared by reacting diaminomaleonitrile with 4-(N,N-dimethylamino)-benzaldehyde and were characterized by ¹H NMR, UV absorption and photoluminescence. The BAM dye showed an absorption peak wavelength of 530 nm and bright photoluminescence with a peak wavelength at 675 nm. It was used as the doped emitter for fabricating a bright scarlet organic electroluminescent (EL) device. The structure of the double-layer EL device consisted of a hole-transport layer and a luminescent layer between ITO glass and magnesium electrodes. The hole-transport layer was a poly(N-vinylcarbazole) (PVK) film. The luminescent layer consisted of a host material, 8-hydroxyquinoline aluminum (Alq₃), and BAM dye as the dopant. A bright light with the peak of 620 nm and narrow bandwidth of 50 nm was obtained in the device with a maximum luminance of 6230 cd/m². The emission spectra almost unchanged as the luminance increased with increasing injection current and the bias voltage. A tentative explanation from both the electronic distribution viewpoint and the molecular geometric analysis for the narrow bandwidth of this red dye was offered.     

ITO薄膜制备及RTA处理对发光器件特性的影响

采用射频反应磁控溅射生长铟锡氧化物(ITO)薄膜,通过X射线衍射(XRD)、透射光谱、四探针法及原子力显微镜(AFM)研究了生长条件、快速热退火(RTA)温度等对薄膜的晶化、透过率、电导率以及表面形貌的影响.以ITO/NPB/AlQ/Al结构的器件为例,讨论了不同的制备条件下ITO薄膜的表面效应对电致发光(EL)的影响,通过EL光谱表征发现,对ITO退火处理后,器件的相对发光强度明显增加,衰减速度减慢,器件的EL光谱有明显的变化.通过进一步分析认为,这是由于ITO薄膜表面的变化引起功函数的改变,从而引起电场重新分布造成的.     

稀土配合物红色有机电致发光器件的研究

以TTA为配体合成了新的共掺杂稀土配合物Tb0.5Eu0.5(TTA)3Dipy,通过与PVK的掺杂,制备了以PVK:Tb0.5Eu0.5(TTA)3 Dipy为发光层的结构为:ITO/PVK:Tb0.5Eu0.5(TTA)3Dipy/BCP/Al的发光器件,在直流电压的驱动下,发现了铕在612 nm处的特征发射,和PVK在410 nm处的发光.此外,还观察到了位于490 nm处的新的发光峰,通过分析研究,认为新的发光来自于稀土配合物的配体和BCP之间相互作用形成的电致激基复合物.用PBD代替了BCP作为电子传输层,制备了结构为:ITO/PVK:Tb0.5Eu0.5(TTA)3DiPy/PBD/Al的发光器件,得到了纯的红色发光.     

两种铽配合物与PVK混合体系的发光机理研究

研究了稀土配合物Tb(p-MBA)₃phen(样品Ⅰ)和Tb(p-ClBA)₃phen(样品Ⅱ)与导电聚合物材料PVK掺杂体系的光致发光和电致发光特性。发现在样品Ⅰ与PVK混合薄膜的光致发光中,除了三价铽离子的发光外,还能看到明显的PVK的发光;而在电致发光中,PVK的发光完全被抑制,只能看到Tb3+的绿光发射。对样品Ⅱ与PVK的混合发光层,无论其光致发光谱还是电致发光谱,都没有看到410 nm处PVK的发射。进一步测量两种材料的激发光谱,初步探讨了器件的发光机理。样品Ⅰ的发光可能来源于两个方面,一是PVK到稀土配合物的不完全的能量传递,二是由于载流子俘获机理;样品Ⅱ的发光则是由于PVK到稀土配合物的完全的能量传递。     

新型低压高效叠层有机白光器件

以Bphen:Li/WO3作为电荷产生层制备了低压、高效有机叠层白光器件. 实验中,首先在器件中引入高导电性的载流子注入和传输层,有效降低了器件的驱动电压,然后通过电荷产生层垂直堆叠两个低压白光器件,获得了低压、高效有机叠层白光器件. 叠层器件性能与单发光单元的器件相比较,其亮度及效率均有大幅提高,叠层器件的最大电流效率达到了17cd/A,在相同的电流密度下,叠层器件的效率约为传统器件的2.3倍,同时由于在叠层结构中引入了高导电性的载流子传输层,有效降低了器件的驱动电压,显著改善了白光器件的流明效率.叠层器件的流明效率相对于单发光单元器件提高了53%.     

未掺杂半绝缘GaAs中受主及电中性EL2分布的研究

测量了未掺杂半绝缘（ＳＩ）ＬＥＣＧａＡｓ中总的、电中性的ＥＬ２及净受主浓度分布和碳分布。结果表明，总ＥＬ２浓度径向分布呈Ｗ形而不是均匀的，净受主浓度径向分布呈∧形或∩形而不是Ｍ形。电中性ＥＬ２的Ｗ形径向分布由总ＥＬ２浓度的Ｗ形径向分布决定，而不是由于净受主的不均匀分布。有些样品中净受主浓度远大于碳浓度．意味着这些样品中除碳外还存在高浓度的其它受主。