2-TNATA对蓝与黄二基色分离的堆叠式白色有机发光器件性能的影响(英文)

研究了2-TNATA厚度对蓝与黄二基色分离的堆叠式白色有机发光器件性能的影响。器件结构为:2-TNATA(xnm)/NPB(25nm)/ADN(30nm)∶TBPE(2%)∶DCJTB(1%)/Alq3(20nm)/LiF(1nm)/Al(100nm)。根据实验结果,2-TNATA的厚度对载流子的注入、色稳定性、热稳定性影响明显。发光器件的颜色可以通过改变加入的2-TNATA层的厚度来改变。这种器件使用2-TNATA作为空穴注入层显示出了色纯度高的白光发射,CIE色坐标x=0.3197,y=0.3496,亮度能够达到12230cd/m2。     

具有PEDOT∶PSS/HAT-CN双空穴注入层的高效柔性OLED器件

为了研究不同的空穴注入层修饰柔性衬底对柔性OLED器件性能的影响,本文采用HAT-CN、PEDOT∶PSS、PEDOT∶PSS/HAT-CN 3种空穴注入层制备柔性OLED器件。设计的器件结构为PET/ITO/HIL/TAPC (60nm)/CBP∶Ir(ppy)3(20nm,10%)/TmPyPB(45nm)/Liq(2nm)/Al(100nm)。采用旋涂的方法制备了PEDOT∶PSS,其余有机层及阴极采用真空蒸镀法制备。结果表明,采用PEDOT∶PSS/HAT-CN复合薄膜作为空穴注入层的柔性OLED器件性能最优。该器件的最大电流效率和最大功率效率分别为84cd/A和76lm/W。研究表明,经PEDOT∶PSS修饰的柔性衬底表面更为连续及平滑,不容易使器件发生漏电及短路现象;同时PET/ITO/PEDOT∶PSS/HATCN复合薄膜在绿光波段有较高的透过率,可以提高器件的出光率;另外该双空穴注入结构使器件内部载流子的注入处于动态平衡状态,增加了电子和空穴载流子的复合概率。     

NPB厚度对堆叠式白光OLED性能的影响

主要研究了NPB厚度对堆叠式白色有机电致发光器件性能的影响。实验制备了四组结构为ITO/2-TNATA(15 nm)/NPB(Tnm)/ADN(30 nm):TBPe(2%):DCJTB(1%)/Alq3(20 nm)/LiF(1 nm)/Al(100 nm)(其中T分别为15,30,35和40 nm)的OLED器件,比较了不同厚度情况下OLED器件的电致发光特性,结果表明:改变NPB(4,4-N,N-bis-N-1-naphthy1-N-pheny1-amino-bipheny1)的厚度能够明显提高器件的发光亮度和发光效率,并调节载流子复合区域的位置,有效提高载流子的注入效果。同时发光器件的颜色也可通过调节NPB层的厚度来改变,这种器件使用NPB作为空穴传输层显示出了色纯度高、亮度好、效率较高的白光发射,其具有CIE色坐标(x=0.301 6,y=0.338 5),最高亮度和最大发光效率分别达到14 020 cd/m2与2.94 lm/W。     

一种新型双空穴注入层微腔OLED

一种新型有机电致发光二极管的阳极结构,在玻璃衬底上以半透明的Al膜为出光面,通过在空穴注入层(HAT-CN)和空穴传输层(NPB)中间插入三氧化钼(MoO3)层,制备了底发射微腔OLEDs。所制备的器件结构为Glass/Al(15nm)/HAT-CN(10nm)/MoO3(x nm)/NPB(30nm)/Alq3(70nm)/LiF(1nm)/Al(150nm)。通过电流密度-电压-亮度性能说明该结构有利于降低驱动电压和增强器件亮度。器件的最高亮度可以达到14 390cd/m2,起亮电压为3.4V左右。设计的空穴型器件证明了该器件结构具有很好的空穴注入和传输特性。研究了光谱窄化和峰值偏移的微腔效应。     

新型间隔层对荧磷杂化白光OLED器件性能的影响

以杂化白光结构ITO/HAT-CN(10 nm)/TAPC(30 nm)/TCTA(10 nm)/TCTA:PO -01(10 nm ,4%)/MADN:DSA-ph(10 nm,5%)/BPhen(40 n m)/Liq(1nm)/Al(100 nm)为基础,分别用CBP 、SO和SO:TCTA作为间隔层,调节厚度及掺杂比例,研究不同间隔层对杂化白光器件性能的 影响。实验结果表明,SO作间隔层可以有效提高电子与空穴在黄光层的复合,增大器件电子 传输能力而使器件偏向白光,提高器件效率,且由于SO高的三线态能级,可以有效控制激子 复合区域的移动,器件色稳定性也得到提高。再将TCTA与SO掺杂作为间隔层,增强空穴传输 ,调控空穴和电子的传输与平衡,进一步提升器件性能,当SO∶TCTA掺杂比为9∶1时,有最大电流效 率31.60 cd/A,最大功率效率30.16 lm/W,电 流密度为10 mA/cm²时,CIE色坐标为(0.39 ,0.43),从0.1 mA/cm²－80 mA/cm²电流密度变化下色坐标变化(Δx,Δy)仅为(0.02),色坐标漂移小,色稳定性好。     

白色磷光OLEDs的制备及性能研究

采用蓝色、黄色磷光混色的发光方式实现白光有机电致发光器件(OLEDS),其中黄色发光层由红色和绿色磷光材料混合而成,器件的结构为ITO/MoO3(30nm)/NPB(40nm)/mCP:FIrpic(8%)(50nm)/CBP:R-4B(1%):GIrl(14%)(xnm)/BCP(10nm)/AlQ(40nm)/LiF(1nm)/Al(100nm)(x=2,3,4,5,6nm)。对器件的效率、亮度等对比发现,当x=5nm时,器件的性能最佳,最大亮度为9 471cd/cm2,效率为23.5cd/A,色坐标(0.32,0.35)。实验表明,影响器件色稳定性和效率低的原因是电子和空穴迁移随驱动电压变化响应不一致引发激子复合区域的移动。     

掺杂C545T对2T-NATA作为空穴注入层OLED性能的影响

实验制备了6组结构为ITO/2T-NATA(15 nm)/NPB(25 nm)/Alq3(20 nm):C545T(x%)/Alq3(30 nm)/LiF(1 nm)/Al(100 nm)的绿光多层结构OLED器件,其中x分别为0、1、2、3、4和5.比较了不同掺杂浓度条件下OLED器件的电致发光特性,结果表明:用2T-NATA作为空穴注入层可有效提高载流子的注入效果,同样能够达到高亮度.将C545T掺杂到Alq3中能够明显改善器件的发光亮度和色纯度,并调节载流子复合区域的位置,有效提高发光效率.掺杂C545T对器件性能的影响显著,随着C545T掺杂浓度的提高,电流和亮度先增大后减小.当掺杂浓度为3%时,14 V电压下的最大发光亮度达到12 418 cd/m2,浓度为2%时的器件,在12 V驱动电压下的最大电流效率为10.22 cd/A.     

利用新型的空穴注入层材料提高有机发光器件性能

研究使用新材料2-TNATA作空穴注入层制备OLED,发现空穴注入层厚度的最佳参数为35 nm,器件的发光光谱随空穴注入层厚度并不发生显著变化,微腔作用对发光光谱的影响基本可以忽略.并将2-TNATA作为空穴注入层的器件同CuPc制作的器件进行了对比,发现使用2-TNATA能获得更佳的器件性能.     

空穴注入层2T-NATA对OLED器件性能的影响

为了提高有机电致发光器件OLED的发光效率,引入2T-NATA作为空穴注入层,制备了结构为ITO/2T-NATA(Xnm)/NPB(25nm)/Alq3:C545T(20nm:质量分数4.5%)/Alq3(30nm)/LiF(1nm)/Al(100nm)的绿光器件,其中X为空穴注入层2T-NATA厚度。分析了2T-NATA的蒸镀厚度分别0,5,10,15,20,25,30,35nm时器件的发光性能。结果表明,2T-NATA的HOMO能级较好的与ITO功函数匹配,降低了空穴注入势垒,引入空穴注入层2T-NATA提高了器件的发光亮度和效率。当2T-NATA厚度为15nm时,器件的效果最好,起亮电压只需2.87V,亮度最高达到18000cd/m2,是不引入空穴注入层亮度的5倍多,在12V时发光效率可达11.4cd/A。     

绿红双发光层有机电致磷光器件的载流子调控研究

制备了结构为ITO/MoO3(40nm)/NPB(40nm)/TCTA(10nm)/CBP∶GIR1(14%)(x)/CBP∶R-4B(6%)(30-x)/BCP(10nm)/AlQ(40nm)/LiF(1nm)/AL(100nm)的绿红磷光器件。通过调节红绿发光层的相对厚度,对器件的发光性能进行了研究。结果表明:x为15nm,电压为6V,电流密度为255.6mA/cm2,得到最高电流效率为15.4cd/A,红色发光峰值强度相对较大,绿色峰值稍弱的电致发光光谱。分析原因可能是掺杂染料与临近层的能级匹配和浓度等会影响发光层载流子注入与传输;空穴及电子阻挡层对发光层内载流子和激子的有效限制作用会提高掺杂染料在发光层的复合几率;另外,CBP的空穴迁移率大于电子迁移率,发光的主要区域位于发光层与BCP界面,掺杂于该区域的R-4B具有较高的发光强度。     

Theoretical investigation of the electronic structure,optical, elastic,hardness and thermodynamics properties of jadeite

A detailed theoretical study of the electronic structure, optical, elastic and thermodynamics properties of jadeite have been performed by means of the first principles based on the state-of-the-art of density functional theory within the generalized gradient approximation. The optimized lattice constants and the atomic positions are in good agreement with experimental data. The total density of states and partial density of states of jadeite have been discussed. The energy gap has been calculated along the Γ direction found to be 5.338 eV, which shows that jadeite has wide direct band gap. The optical properties, such as the dielectric function, refractive index, extinction coefficient, reflectivity coefficient, loss function and absorption coefficient for [100] and [001] directions have been described for the first time in the energy range 0–40 eV. The elastic constants, bulk modulus, Young׳s modulus, anisotropic factor and Poisson׳s ratio have been calculated. Furthermore, the Vickers hardness and Debye temperature of jadeite have been predicted. The calculated values of all above parameters are compared with the available experimental values.     

Theoretical investigation of mechanical,optoelectronic and thermoelectric properties of BiGaO3 and BiInO3 compounds

The cubic BiGaO₃ and BiInO₃ perovskite oxides have been investigated for their structural stability, mechanical and opto-electronic properties by employing the density functional theory. The exchange-correlation effects have been modeled with Perdew–Burke–Ernzerhof generalized gradient approximation, while the improved evaluation of electronic properties has been achieved by using the Tran–Blaha modified form of semi-local Becke–Johnson functional. Structural properties are calculated and the thermodynamics stability of BiGaO₃ and BiInO₃ in the cubic perovskite structure has been established in terms of enthalpies of formation. Furthermore, elastic coefficients such as C_ij, bulk modules B, anisotropy factor, shear modulus G, Young’s modulus Y, Poisson’s ratio ν, and B/G ratio are predicted. Band structure calculations reveal that investigated compounds have an indirect band gap between the occupied O 2p and unoccupied Bi 6p orbitals. The optical response of BiGaO₃ and BiInO₃ are also inspected by computing the complex dielectric function, refractive index, absorption coefficient, extinction coefficient, reflectivity and optical conductivity for radiation with energy up to 16 eV. The important thermoelectric properties of the compounds are described in terms of thermal conductivity, electrical conductivity, Seebeck coefficient and figure of merit.     

Effect of annealing temperature on structural,electrical and optical properties of spray pyrolytic nanocrystalline CdO thin films

Nanocrystalline CdO thin films were prepared onto a glass substrate at substrate temperature of 300 °C by a spray pyrolysis technique. Grown films were annealed at 250, 350, 450 and 550 °C for 2.5 h and studied by the X-ray diffraction, Hall voltage measurement, UV-spectroscopy, and scanning electron microscope. The X-ray diffraction study confirms the cubic structure of as-deposited and annealed films. The grain size increases whereas the dislocation density decreases with increasing annealing temperature. The Hall measurement confirms that CdO is an n-type semiconductor. The carrier density and mobility increase with increasing annealing temperature up to 450 °C. The temperature dependent dc resistivity of as-deposited film shows metallic behavior from room temperature to 370 K after which it is semiconducting in nature. The metallic behavior completely washed out by annealing the samples at different temperatures. Optical transmittance and band gap energy of the films are found to decrease with increasing annealing temperature and the highest transmittance is found in near infrared region. The refractive index and optical conductivity of the CdO thin films enhanced by annealing. Scanning electron microscopy confirms formation of nano-structured CdO thin films with clear grain boundary.     

K+掺杂对SnO2-LiZnVO4系湿敏陶瓷性能的影响

为了提高 SnO_2-LiZnVO_4系湿敏材料的性能,采用共沉淀法制备出 SnO_2-K_2O-LiZnVO_4系纳米湿敏粉体。考察了液相掺杂 K+对材料湿敏性能、复阻抗特性和电容特性的影响。实验结果表明,采用共沉淀法制备纳米粉体并使K+液相掺杂量为 2.5%(摩尔分数),可使湿敏材料低湿电阻小、灵敏度适中,适当的 K+添加量可明显改善 SnO_2-LiZnVO_4系纳米材料的感湿特性。     

Effect of substrate temperature on structural,morphological, optical and electrical properties of MnIn2S4 thin films prepared by nebulizer spray pyrolysis technique

Manganese indium sulphide (MnIn₂S₄) thin films were deposited using an aqueous solution of MnCl₂, InCl₃ and (NH₂)₂CS in the molar ratio 1:2:4 by simple chemical spray pyrolysis technique. The thin film substrates were annealed in the temperature range between 250 and 350 °C to study their various physical properties. The structural properties as studied by X-ray diffraction showed that MnIn₂S₄ thin films have cubic spinel structure. The formation of cube and needle shaped grains was clearly observed from FE-SEM analysis. The energy dispersive spectrum (EDS) predicts the presence of Mn, In and S in the synthesized thin film. From the optical studies, it is analyzed that the maximum absorption co-efficient is in the order between 10⁴ and 10⁵ cm⁻¹ and the maximum transmittance (75%) was noted in the visible and infrared regions. It is noted that, the band gap energy decreases (from 3.20 to 2.77 eV) with an increase of substrate temperature (from 250 to 350 °C). The observations from photoluminescence studies confirm the emission of blue, green, yellow and red bands which corresponds to the wavelength range 370–680 nm. Moreover, from the electrical studies, it is observed that, as the substrate temperature increases the conductivity also increases in the range 0.29–0.41×10⁻⁴ Ω⁻¹ m⁻¹. This confirms the highly semiconducting nature of the film. The thickness of the films was also measured and the values ranged between 537 nm (250 °C) to 483 nm (350 °C). This indicates that, as the substrate temperature increases, the thickness of the film decreases. From the present study, it is reported that the MnIn₂S₄ thin films are polycrystalline in nature and can be used as a suitable ternary semiconductor material for photovoltaic applications.     

Structural,elastic, electronic and thermodynamic properties of uranium filled skutterudites UFe4P12: First principle method

We present a theoretical study of structural, elastic, thermodynamic, and electronic properties of the uranium filled skutterudite UFe₄P₁₂. We use the full-potential linear muffin–tin orbital (FP-LMTO) method in which the local density approximation (LDA) is used for the exchange-correlation (XC) potential. The lattice parameter at equilibrium, the bulk modulus, its pressure derivative, the elastic constants and the band structure energy of the filled skutterudite UFe₄P₁₂ are calculated and systematically compared to available theoretical and experimental data. Herein, we use the total energy variation as function of strain technique to determine independent elastic constants and their pressure dependence. Furthermore, using quasi-harmonic Debye model with phonon effects, the effect of pressure P and temperature T on the lattice parameter, bulk modulus, thermal expansion coefficient, Debye temperature and the heat capacity of UFe₄P₁₂ are investigated for the first time. Band structure of UFe₄P₁₂ indicates a tendency of forming a pseudo-gap that appears above the Fermi level at Γ point. This is a unique characteristic of skutterudite, especially when a single phosphorous p-band crosses the Fermi level. The crossing band is, indeed, pushed down by the repulsion of U f-resonance states.     

Effect of rhenium doping on various physical properties of single crystals of MoSe2

Effect of rhenium doping is examined in single crystals of MoSe₂ viz. MoRe_0.005Se_1.995, MoRe_0.001Se_1.999 and Mo_0.995Re_0.005Se₂, which is grown by using the direct vapor transport (DVT) technique. The grown crystals are structurally characterized by X-ray diffraction, by determining their lattice parameters a and c, and X-ray density. Also, the Hall effect and thermoelectric power (TEP) measurements show that the single crystals exhibit a p-type semiconducting nature. The direct and indirect band gap measurements are also undertaken on these semiconducting materials.     

Effect of rhenium doping on various physical properties of single crystals of MoSe2

正Effect of rhenium doping is examined in single crystals of MoSe_2 viz.MoRe_(0.005)Se_(1.995), MoRe_(0.001)Se_(1.999) and Mo_(0.995)Re_(0.005)Se_2,which is grown by using the direct vapor transport(DVT) technique. The grown crystals are structurally characterized by X-ray diffraction,by determining their lattice parameters a and c,and X-ray density.Also,the Hall effect and thermoelectric power(TEP) measurements show that the single crystals exhibit a p-type semiconducting nature.The direct and indirect band gap measurements are also undertaken on these semiconducting materials.     

Optical,morphological and electrical studies of Zn:PbS thin films

Structural, electrical, and optical properties of undoped and Zn doped lead sulfide (PbS) thin films are benign reported in this paper. The subjected films were grown on glass substrates at 25 °C by a chemical bath deposition (CBD) method. The concentration of Zn in the deposition bath represented by the ratio [Zn²⁺]/[Pb²⁺] was varied from 0% to 5%. It was found that the film׳s grains decreased in size with increasing Zn content in the film. XRD data showed the polycrystalline nature of the film its crystal orientation peak intensities decreased with higher doping concentration of Zn. Atomic force microscopy (AFM) measurements revealed that the surface roughness of the films decreased due to zinc doping as well. However, with increasing of the dopant concentration from 0% to 5%, the average transmittance of the films varied over the range of 35–75%. The estimated optical band (E_g) gaps of undoped and Zn doped PbS thin films were in the range of 0.72–1.46 eV. Hall Effect measurements electrical resistivity, carrier concentration and Hall mobility have been determined for the titled film as functions on the Zn content within the film׳s textures. The overall result of this work suggested that the Zn:PbS film is a good candidate as an absorber layer in the modern solar cell devices.     

Effect of Co doping on structural, optical, electrical and thermal properties of nanostructured ZnO thin films

Nanocrystalline Zn1-x CoxO(where x varies from 0 to 0.04 in steps of 0.01) thin films were deposited onto glass substrate by the spray pyrolysis technique at a substrate temperature of 350 ℃. The X-ray diffraction patterns confirm the formation of hexagonal wurtzite structure. The crystal grain size of these films was found to be in the range of 11–36 nm. The scanning electron micrographs show a highly crystalline nanostructure with different morphologies including rope-like morphology for undoped ZnO and nanowalls and semispherical morphology for Co-doped Zn O. The transmittance increases with increasing Co doping. The optical absorption edge is observed in the transmittance spectra from 530 to 692 nm, which is due to the Co2C absorption bands corresponding to intraionic d–d shifts. The direct and indirect optical band gap energies decrease from 3.05 to 2.75 eV and 3.18 to 3.00 eV, respectively for 4 mol% Co doping. The electrical conductivity increases with increasing both the Co doping and temperature, indicating the semiconducting nature of these films. The temperature dependence thermal electromotive force measurement indicates that both undoped and Co-doped ZnO thin films show p-type semiconducting behavior near room temperature. This behavior dies out beyond 313 K and they become n-type semiconductors.