波长可调谐聚合膜/无机膜异质结电致发光

针对聚合物电致发光材料缺乏可用的电子型聚合物半导体材料的现状,采用无机电子型半导体材料ZnO∶Zn与空穴型聚合物材料PDDOPV[poly (2,5-bis (dodecyloxy)-phenylenevinylene)]成功制备了结构为ITO/PDDOPV/ZnO∶Zn/Al的异质结双层器件.异质结器件的发光效率与亮度较单层器件提高1个数量级以上.该异质结器件的发光颜色是随着电压的增加而蓝移的,其光致发光光谱也随着激发波长的改变而改变,可能形成了新的发光基团.     

波长可调谐聚合膜/无机膜异质结电致发光

针对聚合物电致发光材料缺乏可用的电子型聚合物半导体材料的现状 ,采用无机电子型半导体材料 Zn O∶Zn与空穴型聚合物材料 PDDOPV [poly (2 ,5 - bis (dodecyloxy) - phenylenevinylene) ]成功制备了结构为 ITO/PDDOPV/Zn O∶ Zn/Al的异质结双层器件 .异质结器件的发光效率与亮度较单层器件提高 1个数量级以上 .该异质结器件的发光颜色是随着电压的增加而蓝移的 ,其光致发光光谱也随着激发波长的改变而改变 ,可能形成了新的发光基团 .     

高发光亮度高效率的异质结聚合物电致发光器件

成功制备了可溶性的空穴型聚合物 PDDOPV [poly （2,5-bis （dodecyloxy）-phenylenevinylene）]与电子型聚合物 PPQ [poly（phenyl quinoxaline）]构成的异质结有机薄膜发光二极管。异质结器件的最高亮度是其本身最低亮度的106倍,是 PDDOPV单层器件的 365倍,而最高效率则是 PDDOPV单层器件的 336倍。异质结器件在正向、反向以及交流驱动下均可获得发光,但在正向和交流驱动下的发光来自PDDOPV,而反向驱动下的发光既有来自 PDDOPV的,也有来自 PPQ的。反向偏压下器件获得发光的原因是高场强使得能带高度倾斜,高度倾斜的结果使得载流子的注入势垒变得足够薄从而被载流子隧穿,从而导致载流子的注入和复合。     

高发光亮度高效率的异质结聚合物电致发光器年

成功制备了可溶性的空穴型聚合物PDDOPV(2,5-bis(dodecyloxy)-phenylenevinylene）]与电子型聚合物PPQ[phenyl quinoxaline)]构成的异质结有机薄膜发光二极管。异质结器件的最高亮度是其本身最低亮度的10^6倍，是PDDOPV单层器件的365倍，而最高效率则是PDDOPV单层器件的336倍。异质结器件在正向、反向以及交流驱动下均可获得发光，但在正向和交流驱动下的发光来自PDDOPV，而反向驱动下的发光既有来自PDDOPV的，也有来自PPQ的。反向偏压下器件获得发光的原因是高场强使得能带高度倾斜，高度倾斜的结果使得载流子的注入势垒变得足够薄从而被载流子隧穿，从而导致载流子的注入和复合。     

n型聚合物掺杂p型聚合物单层电致发光器件

成功制备了可溶性n型聚合物PPQ掺杂的可溶性p型聚合物PDDOPV的单层发光器件。与具有相同厚度的纯PDDOPV的单层器件相比，起亮电压从4.5V降低到2.6V；在电压相同的条件下，掺杂的单层器件的电流和纯PDDOPV的单层器件在同一个数量级，但亮度和发光效率均高出1个数量级以上。在10V时，掺杂器件与未掺杂器件的电流、亮度和发光效率的比值分别是1.95,30.9和16.0。掺杂器件亮度和发光效率的大幅提高被归因于在PDDOPV中掺杂PPQ降低了少子的注入势垒，提高了少子注入水平。这一结果表明，在可溶性p型聚合物中掺杂可溶性n型聚合物是提高器件性能的有效方法。     

反向偏压下的压控颜色可调谐聚合物电致发光

成功制备了结构为ITO/PDDOPV/PPQ/Al的异质结聚合物发光二极管，其中PDDOPV是P型聚合物材料，PPQ是n型聚合物材料。该器件在正、反向偏压下均可发光。在正向偏压下的光发射主要来自PDDOPV；在反向偏压下的光发射来自PPQ的蓝光发射和PDDOPV的黄光发射。蓝光强度与黄光强度的比值随着反向偏压的增加而增加。换句话说，该器件的发光颜色是压控可调的，这对实现彩色显示是极为有利的，分析了在反向偏压下的发光机理。     

基于叠层结构的本体异质结有机太阳电池

研究了叠层结构的本体异质结有机太阳电池,下层电池由共轭聚合物（MEH-PPV）作为光敏层,上层电池由共轭聚合物（1VIEDPPV）和ZnO纳米颗粒（50nm）组成光敏层。器件结构为ITO／PEDOT：PSS／MEHPPV／Ag／MEH-PPV：ZnO／Al。与单层有机太阳电池（ITO／PEDOT：PSS／MEH-PPV／Al）相比,叠层结构的开路电压Voc是单层电池的3．7倍,短路电流Jsc是单层电池的1．6倍。     

利用BCP空穴阻挡层改善白光OLED色度的研究

分别将具有空穴传输特性的蓝光材料pNPB和具有电子传输特性的蓝绿光材料Zn（BTZ）2作为2层发光层，将荧光染料rubrene掺入β-NPB中，在发光层间引入5nm具有空穴阻挡作用的BCP层，制备了一种ITO／PVK：β-NPB：rubrene／BCP／Zn（BTZ）。／Mg：Ag/Ag结构白色有机电致发光器件（OLED）。该器件在5V电压下起亮；18V电压下亮度和色坐标分别为1600cd／m^2和（0．31，0．33），最大外量子效率为0．21％。其色度比不含或含较厚BCP层（〉5nm）的器件均有了很大的改善，并从能带结构和空穴阻挡层厚度2方面探讨了色度改善的原因。     

聚合物/纳米半导体电致发光

纳米半导体与聚合物复合形成的新型电致发光材料，在大规模平面显示和移动通信等现代信息显示方面具有广阔的应用前景。在这种复合型电致发光材料体系中，聚合物不仅可用作LED器件的粘接剂，而且在用作无机发光层的分散介质时，对纳米晶粒的表面可以起纯化作用，防止发光猝灭，从而通过控制和调节纳米晶粒的含量和尺寸来调节发光强度和波长。当采用共轭聚合物与纳米半导体形成复合体系时，还可以通过共轭聚合物与纳米半导体间的电子转移来调节发光层的电子结构及其发光性能。利用纳米半导体的高电荷输运性，也可以增强电致发光聚合物发光层的效率。     

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。     

Efficient polymer light-emitting diodes with ZnO nanoparticles and interpretation of observed sub-bandgap turn-on phenomenon

Low-temperature liquid-phase synthesized ZnO nanoparticles (NPs) are used to realize highly-efficient polymer light-emitting diodes (PLEDs) containing a poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) emissive layer. It is shown that a 77-nm-thick ZnO electron transport layer (ETL) increases the maximum luminance and current efficiency of the PLED from ∼450 to ∼13,100 cd/m² and 0.55–4.7 cd/A, respectively. In addition, the ZnO layer shifts the peak in the electroluminescence (EL) spectrum from ∼535 nm for a PLED with a CsN₃ layer or no NP layer to ∼585 nm. After ruling out the possibility of ZnO-defect-related emissions and micro-cavity or interference effects, it is argued that the sub-bandgap turn-on behavior of the PLED with a ZnO ETL is the result of emission zone transition and enhanced hole injection rate near the anode, based on the trap-filled space-charge limited conduction (SCLC) phenomenon in the current density-voltage curves and the current-dependent EL spectra.     

以ZnO为空穴缓冲层的高效率有机电致发光器件

研制了在传统双层有机电致发光器件(OLED) ITO/NPB/AlQ/Al的阳极与空穴传输层间加入ZnO缓冲层的新型器件.研究了加入缓冲层后对OLED性能的影响,并比较了新型与传统OLED的性能,结果表明,新型器件比传统器件的耐压能力有了显著提高;当电压达到7 V时,发光效率提高了35%.分析认为,ZnO缓冲层的加入,改善了界面, 减少了漏电流,并且阻碍了空穴的注入,有利于改善空穴和电子的注入平衡,提高复合效率.     

Alternating-Current White Thin-Film Light-Emitting Diodes Based on Hydrogenated Amorphous Carbon Layer

Alternating-current white thin-film light-emitting diodes (ACW-TFLEDs) have been fabricated and demonstrated with composition-graded hydrogenated intrinsic amorphous silicon carbide (i-a-SiC : H) layers. It was found that H₂-plasma treatment of luminescent i-a-C : H layer played an important role in decreasing the ACW-TFLED electroluminescence (EL) threshold voltage, increasing the brightness, and broadening the EL spectrum. The EL spectra of the ACW-TFLED under either dc forward or reverse bias, or the sinusoidal alternating-current voltage were qualitatively very similar, with a peak wavelength at about 505 nm and a broad full-width at half maximum (FWHM) about 240 nm. This device revealed a brightness about 800(500)cd/m² under dc forward (reverse) bias at an injection current density of 600 mA/cm²     

Interfacial engineering of ZnO nanoarrays as electron transport layer for polymer solar cells

Highly uniform one-dimensional ZnO nanoarrays (ZnO NAs) fabricated by hydrothermal process were successfully explored as electron transport layer (ETL) for offering a direct and efficient path for electron transport in inverted polymer solar cells (PSCs). The inorganic CdS shell layer by in situ growth on the ZnO NAs surface was used to passivate and repair the surface defects of ZnO NAs. To further engineer the ZnO surface and improve the compatibility between ETL of inorganic ZnO/CdS core/shell and polymer blend contact junction, those organic molecules of 3,6,7,10,11-pentakis-(hexyloxy)-2-hydroxytriphenylene (TP-OH), 1-pyrenol (Py-OH) and 4′-(7-hydroxy-heptanoyl)-biphenyl-4-carbonitrile (BP-OH) were respectively spin-coated on the ZnO NAs/CdS surface to fabricate ETL based on ZnO/CdS/TP-OH NAs, ZnO/CdS/Py-OH NAs, ZnO/CdS/BP-OH NAs. The π–π interactions between the organic molecules and fullerene acceptors could lead to the well-organized distribution of active layer materials, which is in favor of the enhancement of electron selectivity and the reduction of recombination probability of electrons and holes. The incorporation of ZnO/CdS/Py-OH NAs as ETL into the inverted PSCs based on P3HT:PC₆₁BM resulted in a superior power conversion efficiency (PCE) of 4.2% with enhanced short circuit current (J_sc) and fill factor (FF), compared to 3.1% for bare ZnO NAs, due to the intermolecular close-stacking and relative stronger π–π interaction energy between Py-OH and fullerenes. In addition, the sensitized ZnO surface led to intimate interface between ETL and active layer, which would be in favor of increasing the stability of the device.     

MgO界面层对n-ZnO纳米棒/p-GaN异质结LED光电性能的影响

为了较好地实现n-ZnO的电致发光(EL),利用水热法在p-GaN外延片上制备了ZnO纳米棒阵列,构造了n-ZnO纳米棒/p-GaN异质结LED原型器件,并研究了MgO界面层对器件光电性能的影响。结果表明,n-ZnO纳米棒/p-GaN异质结器件具有明显的二极管整流效应。室温、正向偏压下,n-ZnO纳米棒/p-GaN异质结LED仅在430nm附近具有单一的发光峰,而n-ZnO纳米棒/MgO/p-GaN异质结LED的电致发光光谱由一个从近紫外到蓝绿光区的宽发光带组成。结合光致发光(PL)谱和Anderson能带模型,深入分析了n-ZnO纳米棒/p-GaN异质结的载流子复合机制。     

Improved efficiency in green polymer light-emitting diodes with air-stable electrodes

By dispersing an electron transporting molecular dopant into the active semiconducting luminescent polymer, we have achieved improved efficiencies for green light-emitting diodes (LEDs). These green emitting LEDs were fabricated by adding an electron transporting molecular dopant, 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-l,3,4-oxadiazole (PBD), into the semiconducting luminescent polymer as the emitting layer in the polymer LEDs. The devices used poly(2-cholestanoxy-5-thexyldimethylsilyl-l,4-phenylene vinylene) (CS-PPV), a new soluble green light emitter, as the semiconducting luminescent polymer and either aluminum or indium as the electron injection electrodes. Quantum efficiencies of LEDs with the electron transporting molecular additive in the luminescent polymer and an Al electrode are about 0.3% photons per electron, better by a factor of 18 than similar devices made without the addition of the electron transport molecular dopant; quantum efficiencies of similar LEDs fabricated with an In electrode are 0.23% photons per electron, better by a factor of 16 than devices without the electron transport molecular additive.     

Improved performance of mixed single layer top-emission organic light emitting devices using capping layer

The performance of top-emission organic light emitting devices (TEOLEDs) can be improved by using a thin capping layer on top of the semitransparent metal electrode. We investigated the emission properties of inverted mixed single layer TEOLEDs with the same device structure but different capping materials. The thickness of capping layer was optimized by calculation. The power efficiency of device was 2.5 times enhanced when 45 nm TPD capping layer was added. The enhancement is not simply dependent on the transmittance and reflectance of the top contact, but also on other complex phenomena such as the interference effects in the device. The results of properties and dependence of EL spectra on viewing angle for all devices indicated that the large enhancement factor may be related to the complex interference phenomenon in our mixed single layer devices due to the emitter center and recombination region is different from conventional heterojunction devices.     

基于TPD:PO-T2T的黄光激基复合物发光性能研究

通过多源有机分子气相沉积系统(LN-386SA)制备结构为ITO/HAT-CN/TPD/TPD:PO-T2T/PO-T2T(x=10,20,30,40,50,60,70 nm)/LiF/Al的有机发光器件,研究了电子传输层(PO-T2T)厚度对TPD:PO-T2T黄光激基复合物发光性能的影响。PO-T2T厚度对其电致发光(electroluminescence, EL)光谱几乎没有影响,但对电流密度(current density, CD)、亮度、效率等性能有较大影响。由于金属铝扩散至发光层中会形成淬灭中心降低发光效率,当PO-T2T越厚时,扩散至发光层的铝原子越少,因此发光效率随PO-T2T厚度增加而增加。当PO-T2T厚度为70 nm时,获得最大电流效率(current efficiency, CE)和功率效率(power efficiency, PE),分别为2.16 cd/A、2.12 lm/W。此外,瞬态EL性能表明TPD:PO-T2T的发光来自TPD和PO-T2T分别对载流子的直接捕获,没有发光瞬时过冲或者深陷阱中载流子逃逸复合发光的现象。