聚乙烯咔唑／铟锡氧化物的界面分析

用原子力显微镜(AFM)和X射线光电子能谱(XPS)研究了真空蒸镀聚乙烯咔唑(PVK)薄膜的表面形貌和PVK／铟锡氧化物(ITO)界面电子状态。结果表明，PVK分子虽然体积较大，但分布较均匀。XPS数据显示，在界面处PVK分子骨架和SnO2分子结构几乎没有发生变化，但PVK分子的侧基和In2O2分子结构发生了变化，因为界面处存在大量的，不能用制备过程的空气污染来解释的C-O键；在界面处，In2O3分子部分分解，所产生O原子替代PVK侧基上的H原子而形成C—O键；所产生的In原子则扩散至PVK内部。     

不同粒径的SiO_2纳米粒子与PVK分子复合体系的发光性质研究

通过溶胶-凝胶的方法,在乙醇溶液中合成了40nm和60nm两种不同粒径的SiO2纳米粒子,并将其分别与聚乙烯咔唑(PVK)混和,得到了不同粒径、不同质量分数配比的PVK/SiO2纳米粒子复合体系;利用光致发光光谱、吸收光谱和喇曼光谱,深入研究了PVK分子在不同状态条件下的发光特性和PVK/SiO2纳米粒子复合体系的光学性质;在复合体系中,观察到PVK与SiO2纳米粒子之间的界面能量转移过程,且不同粒径的SiO2纳米粒子对PVK分子的发光性质影响也不同。通过喇曼光谱的进一步研究表明,SiO2纳米粒子的存在,使PVK分子的振动能量明显减小,表明PVK分子与SiO2纳米粒子表面存在较强的相互作用。     

Thermal Properties of 12-Fold Quasi-Photonic Crystal Microcavity Laser With Size-Controlled Nano-Post for Electrical Driving

In this report, we investigate the fabrication process of 12-fold quasi-photonic crystal microcavity with size-controlled nano-post beneath for electrically-driven structure by fine-tuning the wet-etching time. By finite-element method, we simulate and analyze the heat transfer behaviors of microcavities with different nano-post sizes and shapes. From the real devices, we obtain whispering-gallery (WG) single-mode lasing action with high measured quality factor of 8 250 and low threshold of 0.6 mW when the nano-post size is as large as 830 nm in diameter. By varying the substrate temperature, WG single-mode lasing action is still obtained when the substrate temperature is as high as 70degC. Besides, the lasing wavelength red-shift rate is also improved compared with the microcavity without nano-post beneath. By varying the pump condition, lasing action is still observed at room temperature when the pump duty cycle increases to 16.0%. Thus, for electrically-driven photonic crystal microcavity lasers, this nano-post can serve as current injection pathway and heat sink at the same time.     

LPPP异质结构薄膜发光器性能增强的研究

研究了以空穴型梯型聚次苯基（LPPP）和电子型八羟基喹啉铝（Alq3）组成的光发射器发射效率提高的方法，发光器的结构为Au／LPPP／Alq3／Al，测试结果表明这种发光器微腔调谐效应显著，净发射效率得到提高。     

Electrically injected single-defect photonic bandgapsurface-emitting laser at room temperature

An electrically injected defect-mode photonic bandgap microcavity surface-emitting laser at room temperature is demonstrated for the first time. 931 nm lasing is observed under pulsed excitation conditions. With a threshold current of 300 μA. Near- and far-field modal characteristics of the emission confirm lasing from the defect-related microcavity in the photonic bandgap crystal     

有机小分子掺杂的聚合物共混发光二极管

报道了用可溶性发光材料聚（２,５－二丁氧基苯）做发光材料,分别与母体聚合物聚乙烯基咔唑（ＰＶＫ）和聚甲基丙烯酸甲脂（ＰＭＭＡ）共混,并掺杂电子传输材料叔丁基联苯基苯基口恶二唑和空穴传输材料二胺衍生物作发光层,用铟锡氧化物和铝分别作正负电极,制作了两种蓝紫光有机／聚合物单层发光器件。通过比较两种器件的器件特性,发现以ＰＭＭＡ做母体的器件比用ＰＶＫ做母体的器件有更好的稳定性,器件开启电压为１０Ｖ左右,发光峰值波长均位于４２４ｎｍ,电致发光效率可达２．９％,比用ＰＶＫ做母体的器件效率高一倍多。     

Method for Preparation of Semiconductor Quantum‐Rod Lasers in a Cylindrical Microcavity

An efficient method for preparation of semiconductor quantum rod films for robust lasing in a cylindrical microcavity is reported. A capillary tube, serving as the laser cavity, is filled with a solution of nanocrystals and irradiated with a series of intense nanosecond laser pulses to produce a nanocrystal film on the capillary surface. The films exhibit intense room‐temperature lasing in whispering‐gallery modes that develop at the film–capillary interface as corroborated from the spacing detected for the lasing modes. Good lasing stability is observed at moderate pump powers. The method was applied successfully to several quantum‐rod samples of various sizes.     

Very small oxide-confined vertical microcavity lasers withhigh-contrast AlGaAs-AlxOy mirrors

We report the photo-pumped lasing action from a very small oxide-confined 870-nm vertical microcavity lasers with high-contrast AlGaAs-Al_xO_y mirrors. The effective cavity length is as small as 0.37 μm, and the oxide aperture size is 0.73 μm, estimated from the blue-shift of lasing mode due to the lateral confinement. The observed blue-shift of the lasing mode is 13.4 nm, the largest one ever reported for vertical cavity lasers. The optical losses seem to be size-independent for these small microcavity lasers. Our results indicate the possibility of the ultimate microcavity of order of λ³     

Charge-transport characteristics in bistable resistive Poly(N-vinylcarbazole) films

Charge-transport characteristics of bistable resistive poly(N-vinylcarbazole) films as a function of temperature have been investigated. It is found that the on-state charge transport is dominated by ohmic conduction, hopping with an energy scale of the order of /spl sim/ 20 meV. The off-state charge transport appears to follow a transition from ohmic to space charge limited conduction with a shallow-trap distribution. Nonetheless, the poly(N-vinylcarbazole) (PVK) film does not possess its memory characteristics when operated at temperatures higher than 410 K. The PVK film can be operated at low voltage (< 2 V) with a high on/off current ratio as large as 10/sup 6/.     

Enhanced performance of spectra stable blue perovskite light-emitting diodes through Poly(9-vinylcarbazole) interlayer incorporation

Since the emergence of organic-inorganic hybrid perovskites, the development of perovskite light-emitting diodes (PeLEDs) with green/red emission have made great progress, and the corresponding external quantum efficiency (EQE) has exceeded 20%. However, the research progress of blue-emitting PeLED still has certain challenges. In this article, a multi-cation per-bromine perovskite film is prepared by introducing polymer molecules poly(9-vinylcarbazole) (PVK) in an anti-solvent (chloroform). When the concentration of PVK is optimized to 0.1 mg/mL, a smooth, dense, high-quality film with photoluminescence quantum efficiency (PLQY) up to 20.70% is obtained. The introduction of PVK can assist the formation of perovskite films for interface modification via surface defect passivation. The optimized blue PeLED has a maximum brightness of 3136 cd/m² and a maximum EQE of 3.49% at 488 nm. More importantly, the optimized blue PeLED has excellent color stability under high applied voltage up to 12 V or continuous operation.     

Avoiding trap states in poly(n-vinylcarbazole) thin films

Optical properties of poly(n-vinylcarbazole) (PVK) thin films are revisited. Steady-state emission spectra put in evidence a strong red band whose intensity increases with decreasing temperature when the solid state PVK film is excited by a continuous 375 nm laser line. This red band is assigned to the emission from PVK aggregate states which act as trap states for the monomeric PVK triplet high energy (blue) excitons. At the same low temperatures, these trap states can be avoided when the excitation of the PVK film is made by a 355 nm pulsed laser line with 10 Hz repetition rate. The red band was also observed to compete with the emission of guest poly(3-octadecylthiophene) (PODT) molecules in a PVK/PODT sequential bilayer structure. Different optical geometries enabled us to show that the exciton energy transfer effect from PVK donor to PODT acceptor states dominates the scenario in the bilayer structure, suppressing almost completely the trap state emissions.     

Hole Mobility in Poly（N—vinylcarbazole） Thin Film Based on Silicium^①②

The mobilities of holes in thin,spin-casting films of poly( N -vinylcarbazole)(PVK) based on silicium are measured using a time-of-flight (TOF) technique.The drift of hole mobility is strongly dependent on the electric field and temperature.At room temperature and an electric field of 2×10 5 V·cm -1 ,the effective mobility of hole is 7.14×10 -6 cm 2·V -1 ·s -1 ,in a 200 nm thick sample.     

基于液晶/聚合物光栅选频的高效率有机半导体激光器

报道了一种基于液晶/聚合物光栅选频的高效率有机半导体激光器的制备方法。首先在一片玻璃基板上旋涂有机半导体荧光薄膜MEH-PPV作为增益介质,然后在其上通过光场中的定域光聚合制备液晶/聚合物光栅,形成分布式反馈(DFB)有机半导体激光器。激光出射阈值0.32μJ/pulse,斜率转化效率高达7.8%,呈现良好的s偏振特性。采集了激光束的光斑,轮廓清晰,呈现扇形结构。通过改变光栅周期,实现了53.4nm激光出射范围。本工作为新型有机激光器的制备提供了有益的指导和借鉴意义。     

PVK:NPB复合空穴传输层对有机电致发光器件的影响

采用poly(N-vinylearbazole)(PVK):N,N'-bis-(1-naphthyl)-N,N'-bipheny-1,1'-biphenyl-4,4'-diamine(NPB)掺杂体系作为复合空穴传输层,通过调节该体系的组分,制备了结构为indium-tin oxide(ITO)/PVK:NPB/8-hydroxyquinoline aluminum(Alq3)/Mg:Ag的双层有机电致发光器件(OLED),研究了具有不同掺杂质量比的OLED器件的电致发光特性,并对掺杂薄膜的表面形貌进行了表征.结果表明,将NPB掺杂到PVK中会提高空穴传输能力,改善器件的发光亮度和效率,并调节载流子复合区域的位置,光谱谱峰从509 nm移动到530 mm;但随着NPB质量比例提高,掺杂薄膜表面的平均粗糙度由3 nm上升为10 mm,电流密度和亮度先升高后降低.当PVK和NPB的掺杂质量比为l:3时,器件具有最优性能,发光亮度达到7852 cd/m2,功率效率为1.75 lm/W.     

Spontaneous emission factor of a microcavity DBR surface-emittinglaser

The spontaneous emission factor (SEF) of a microcavity distributed Bragg reflector (DBR) surface-emitting laser has been obtained theoretically to investigate the possibility of the thresholdless lasing operation. Formulas expressing the spontaneous emission in a three-dimensional microcavity were obtained. By introducing the distribution of mode density in wavevector space, it is shown that the radiation pattern of spontaneous emission is deeply modified by the microcavity and is different from that in free space. Based on this result, the SEF and the emission lifetime are calculated as a function of emission spectral width and the size of the active region. It is found that the SEF exceeds 0.1, even though the spectral width is as large as 30 nm when the transverse size is smaller than 0.5 μm and the DBR reflectivity is larger than 90%     

Suppression of the viewing angle dependence by introduction of nanoporous diffuser film on blue OLEDs with strong microcavity effect

A nanoporous polymer film composed of cellulose acetate butyrate was prepared, which showed an optical haze property of approximately 40%. This film was applied as a diffuser film to improve the viewing angle dependence of microcavity structured organic light emitting diodes (OLEDs). We prepared this film by simply using a spin-coating process with a continuous supply of water mist from a humidifier. Air voids or pores with diameters ranging from 300 nm to 500 nm were found inside the polymer film, to produce three-dimensional (3D) nanoporous polymer films with random distribution. We applied this film to a blue fluorescent OLED device with strong microcavity effect. The film did not affect the total external quantum efficiency (EQE) observed using an integrating sphere. However, the current efficiency collected from the normal direction was reduced by 25%, which means that the film spread out or scattered the light emitted from the OLED device. As a result, we obtained blue microcavity OLEDs with efficiently reduced viewing angle dependency.     

Plasmonically enhanced lasing by different size silver nanoparticles-silver film hybrid structure

We reported on the enhanced lasing in organic dyes based on plasmonic hybrid structure of Ag nanoparticles (NPs)-Ag film, the diameters of Ag NPs ranged from 20 nm to 100 nm. The lowest lasing threshold was achieved by the optimal size Ag NPs-Ag film hybrid structure, which was reduced by 5.2 times than that of the neat gain medium. Comparing to the separate Ag NPs or Ag film, the hybrid structure presented the more intense local electric field due to the plasmonics coupling between the localized surface plasmons of Ag NPs and the surface plasmon polariton of Ag film, and the stronger scattering due to the reinjection of the leaking photons by external feedback of Ag film. The effects of different sizes Ag NPs-Ag film hybrid structures on lasing were investigated. It found that when the Ag NPs in hybrid structure is small (diameter≤40 nm), the enhanced localized electric field plays a major role on enhanced lasing; with the increase of Ag NPs size, the enhanced electric field and scattering have comparable contribution on enhancing lasing; for the larger size Ag NPs-Ag film (diameter≥80 nm), the scattering effect is the dominant mechanism for random lasing. Then the lowest threshold was dominated by the balance of enhanced localized electric field and scattering effect. Our results could provide us a unique idea to effectively enhance the lasing of organic dyes, and realize the lower pumped threshold and stronger lasing.     

金属阳极厚度对OLED微腔器件性能的影响

制作了一种以Al为金属反射膜和金属半透膜的微腔有机电致发光器件(OLED)。器件结构是:Al/MoO3/NPB/ADN∶TBPe∶DCJTB/Alq3/LiF/Al。设计了五种厚度的金属Al阳极半透膜器件,Al半透膜的厚度依次为:12nm,13nm,14nm,15nm,16nm。通过调节阳极Al半透膜的厚度,改变微腔的光学长度,研究微腔效应对器件性能的影响。利用Al半透膜阳极厚度的变化,调整微腔器件的光学长度,发光效率和色纯度也随之变化。当Al半透膜为12nm时,器件在11V获得最高亮度3 381cd/m2,最高效率为2.01cd/A,色坐标为(0.33,0.39)。实验表明,合理利用微腔效应,可提高以Al为阳极器件的色纯度,并保持一定的发光效率。     

Microcavity distributed-feedback laser using dye-doped polymeric thin films

An organic microcavity laser, in which all the stacked polymer layers are doped with pyrromethene-567 dye, is presented. Singlemode laser oscillation at 568 nm was obtained that was located in the middle of the stopband. The lasing threshold was found to be 260 nJ/pulse, which corresponded to 300 muJ/cm² in the pulse energy density     

OLED with a controlled molecular weight of the PVK (poly(9-vinylcarbazole)) formed by a reactive ink-jet process

An ink-jet printing method was proposed to solve several conventional problems of ink jet process. PVK (poly(9-vinylcarbazole)) thin film was synthesized and simultaneousely patterned by the reactive ink-jet process (RIP). Gel permeation chromatography shows a linear relationship between the molecular weight of the PVK and the reaction time. The as-synthesized PVK with a controlled molecular weight was applied to an OLED device. Most of the OLED with the RIP–PVK film performed better compared to the reference OLEDs. The luminance graphs indicated the existence of a proper molecular weight leading to the optimum structural conformity which was matched well to the modified OLED structure, showing a linear relationship with the reaction time in the turn-on threshold. This result implies that one can control the proper molecular weight of a polymer and thus the electrical properties of an OLED device via the RIP method.