MoO3–Au composite interfacial layer for high efficiency and air-stable organic solar cells

Efficient and stable polymer bulk-heterojunction solar cells based on regioregular poly(3-hexylthiophene):[6,6]-phenyl-C₆₁-butyric acid methyl ester (P3HT:PC₆₁BM) blend active layer have been fabricated with a MoO₃–Au co-evaporation composite film as the anode interfacial layer (AIL). The optical and electrical properties of the composite MoO₃–Au film can be tuned by altering the concentration of Au. A composite film with 30% (weight ratio) Au was used as the AIL and showed a better performance than both pure MoO₃ and PEDOT:PSS as AIL. The surface morphology of the MoO₃–Au composite film was investigated by atomic force microscopy (AFM) and showed that the originally rough ITO substrate became smooth after depositing the composite film, with the root mean square roughness (RMS) decreased from 4.08 nm to 1.81 nm. The smooth surface reduced the bias-dependent carrier recombination, resulting in a large shunt resistance and thus improving the fill factor and efficiency of the devices. Additionally, the air stability of devices with different AILs (MoO₃–Au composite, MoO₃ and PEDOT:PSS) were studied and it was found that the MoO₃–Au composite layer remarkably improved the stability of the solar cells with shelf life-time enhanced by more than 3 and 40 times compared with pure MoO₃ layer and PEDOT:PSS layer, respectively. We argue that the stability improvement might be related with the defect states in MoO₃ component.     

Tricolor microcavity OLEDs based on P-nc-Si:H films as the complex anodes

A P+-nc-Si:H film (boron-doped nc-Si:H thin film) was used as a complex anode of an OLED. As an ideal candidate for the composite anode, the P+-nc-Si:H thin film has a good conductivity with a high work function (～5.7 eV) and outstanding optical properties of high reflectivity, transmission, and a very low absorption. As a result, the combination of the relatively high reflectivity of a P+-nc-Si:H film/ITO complex anode with the very high reflectivity of an Al cathode could form a micro-cavity structure with a certain Q to improve the efficiency of the OLED fabricated on it. An RGB pixel generated by microcavity OLEDs is beneficial for both the reduction of the light loss and the improvement of the color purity and the efficiency. The small molecule Alq would be useful for the emitting light layer (EML) of the MOLED, and the P+-nc-Si film would be used as a complex anode of the MOLED, whose configuration can be constructed as Glass/LTO/P+-nc-Si:H/ITO/MoO3/NPB/Alq/LiF/Al. By adjusting the thickness of the organic layer NPB/Alq, the optical length of the microcavity and the REB colors of the device can be obtained. The peak wavelengths of an OLED are located at 486, 550, and 608 nm, respectively.The CIE coordinates are (0.21,0.45), (0.33,0.63), and (0.54,0.54), and the full widths at half maximum (FWHM)are 35, 32, and 39 nm for red, green, and blue, respectively.     

Enhancement of hole injection with an ultra-thin Ag2O modified anode in organic light-emitting diodes

The interface between the organic layer and the Indium Tin Oxide (ITO) layer of an organic light-emitting diode (OLED) is crucial to the performance of the device. An ultra-thin Ag₂O film, used as an anode modification layer, has been employed on ITO surface through the UV-ozone treatment of Ag films. The insertion of this thin film with higher work function enhances the hole injection in the organic light-emitting diode and improves the performance of the devices effectively. The maximum electroluminescence (EL) efficiency of the device with the Ag₂O film is 4.95 cd/A, it is about 60% higher than that of the device without it.     

基于纳米硅薄膜复合阳极的微腔调色法的研究

A P^＋-nc-Si：H film（boron-doped nc-Si：H thin film） was used as a complex anode of an OLED.As an ideal candidate for the composite anode,the P^＋-nc-Si：H thin film has a good conductivity with a high work function（- 5.7 eV） and outstanding optical properties of high reflectivity,transmission,and a very low absorption.As a result,the combination of the relatively high reflectivity of a P^＋-nc-Si：H film/ITO complex anode with the very high reflectivity of an Al cathode could form a micro-cavity structure with a certain Q to improve the efficiency of the OLED fabricated on it.An RGB pixel generated by microcavity OLEDs is beneficial for both the reduction of the light loss and the improvement of the color purity and the efficiency.The small molecule Alq would be useful for the emitting light layer（EML） of the MOLED,and the P^＋-nc-Si film would be used as a complex anode of the MOLED,whose configuration can be constructed as Glass/LTO/P^＋-nc-Si：H/ITO/MoO3/NPB/Alq/LiF/Al.By adjusting the thickness of the organic layer NPB/Alq,the optical length of the microcavity and the REB colors of the device can be obtained.The peak wavelengths of an OLED are located at 486,550,and 608 nm,respectively.The CIE coordinates are（0.21,0.45）,（0.33,0.63）,and（0.54,0.54）,and the full widths at half maximum（FWHM） are 35,32,and 39 nm for red,green,and blue,respectively.     

电极界面修饰对PLEDs器件性能的影响

为了研究阴阳极界面修饰对聚合物电致发光器件（PLEDs）性能的影响,文中以ITO/MEH-PPV/Al为原型器件,研究了氧化石墨烯（GO）或者氟化铯（CsF）阴极界面修饰,GO或者PEDOT∶PSS阳极界面修饰对器件性能改善的影响.结果显示：CsF在修饰阴极界面时起到了主导性作用,使得PLEDs的发光亮度显著提高,而GO在修饰阴极界面时却没有这样的效果;但实验发现,GO有望成为新一代的阳极界面修饰材料,替代PEDOT∶PSS修饰ITO阳极.     

Flexible organic light-emitting diodes on a polyestersulfone (PES) substrate using Al-doped ZnO anode grown by dual-plasma-enhanced metalorganic deposition system

This study proposes flexible organic light-emitting diodes (OLEDs) grown on polyestersulfone (PES) using Al-doped zinc oxide (AZO) as the anode, fabricated by the dual-plasma-enhanced chemical vapor deposition (DPEMOCVD) system. The experimental results including crystalline structure, optical, and electrical characteristics indicate that the quality of AZO films grown on PES depends on the deposition temperature and Al content. The optimal deposition temperature and Al content for AZO film are 185  C and 2.88 at%, respectively. Further increasing or decreasing the deposition temperature and Al content degrades the quality of AZO films. The optimal AZO film deposited on the PES substrate was used as the anode for flexible OLED. It shows a similar performance compared to OLEDs using commercial indium–tin-oxide (ITO) as the anode on glass, and represents enhanced characteristics to that of the commercial ITO anode on a flexible polyethylene naphthalate (PEN) substrate. This indicates that the DPEMOCVD-deposited AZO film on the PES substrate can be the anode for flexible OLEDs.     

基于MIC多晶硅薄膜阳极的微腔有机发光器件

通过对溶液法金属诱导晶化多晶硅薄膜制备工艺的优化,制备出性能良好的P型掺杂多晶硅薄膜。厚度为50nm的MICP+-Poly-Si薄膜的方块电阻可降低至400Ω左右,其光学特性表现为在红光区域具有比较高的反射率和很小的吸收率,因此用它替代ITO用作红光OLED的阳极材料。由于此薄膜对可见光比较高的反射率和阴极铝对可见光的高反射性,使之形成了一定Q值的微腔效应。结果显示该器件的最大流明效率为5.88cd/A,比用ITO作阳极制备的OLED提高了57%。进一步优化器件结构,调整发光层在腔中的最佳位置,可以大大增强发光强度,从而可以实现发光强度高、单色性好的红色微腔有机电致发光显示器件。     

Fabrication of a “Soft” Membrane Electrode Assembly Using Layer‐by‐Layer Technology

A new type of thin‐film electrode that does not utilize conducting polymers or traditional metal or chemical vapor deposition methods has been developed to create ultrathin flexible electrodes for fuel cells. Using the layer‐by‐layer (LbL) technique, carbon–polymer electrodes have been assembled from polyelectrolytes and stable carbon colloidal dispersions. Thin‐film LbL polyelectrolyte–carbon electrodes (LPCEs) have been successfully assembled atop both metallic and non‐metallic, porous and non‐porous substrates. These electrodes exhibit high electronic conductivities of 2–4 S cm^–1, and their porous structure provides ionic conductivities in the range of 10^–4 to 10^–3 S cm^–1. The electrodes show remarkable stability towards oxidizing, acidic, or delaminating basic solutions. In particular, an LPCE consisting of poly(diallyldimethyl ammonium chloride)/poly(2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid)/carbon–platinum assembled on a porous stainless steel support yields an open‐circuit potential similar to that of a pure platinum electrode. With LbL carbon–polymer electrodes, the membrane‐electrode assembly (MEA) in a fuel cell can be made several times thinner, assume multiple geometries, and hence be more compact. The mechanism for LPCE deposition, electrode structure, and miniaturization will be presented and discussed, and demonstrations of the LbL electrodes in a traditional Nafion‐based proton fuel cell and the first demonstration of a thin‐film hydrogen–air “soft” fuel cell fully constructed using multilayer assembly are described.     

基于AM-OLED基板的拓展多晶硅薄膜功能层的研究

在有源寻址有机发光二极管（active matrix organic light emitting diode, AM-OLED）显示基板中,将电学功能层--薄膜晶体管（thin film transistor, TFT) 有源层材料p型掺杂金属诱导晶化（metal induced crystallized, MIC）多晶硅（p+-MIC poly-Si）薄膜的版图适当延伸,来充当OLED的阳极,由于它具有低方块电阻、高功函数的电学特性和半反半透、低吸收率的光学特性,与OLED的金属铝阴极形成了微腔器件,成功地形成了显示基板上的多晶硅薄膜的光学功能层. 对这一功能层的厚度进行了优化,比较了不同厚度下TFT器件的电学特性和OLED的光学特性. 当其厚度为40nm时为最佳厚度,此时,TFT器件场迁移率、阈值电压、亚阈值幅摆、电流开关比和栅压诱导漏极漏电等性能为最佳,且红光微腔式OLED (microcavity-OLED, MOLED）的出光强度增大,光谱窄化,电流效率与功率效率均有所提高. 这不仅使器件的性能有所提高,而且大大地简化了AM-OLED基板的制备流程.     

A Transparent,Flexible, Low‐Temperature,and Solution‐Processible Graphene Composite Electrode

The synthesis and preparation of a new type of graphene composite material suitable for spin‐coating into conductive, transparent, and flexible thin film electrodes in ambient conditions is reported here for the first time. Solution‐processible graphene with diameter up to 50 μm is synthesized by surfactant‐assisted exfoliation of graphite oxide and in situ chemical reduction in a large quantity. Spin‐coating the mixing solution of surfactant‐functionalized graphene and PEDOT:PSS yields the graphene composite electrode (GCE) without the need for high temperature annealing, chemical vapor deposition, or any additional transfer‐printing process. The conductivity and transparency of GCE are at the same level as those of an indium tin oxide (ITO) electrode. Importantly, it exhibits high stability (both mechanical and electrical) in bending tests of at least 1000 cycles. The performance of organic light‐emitting diodes based on a GCE anode is comparable, if not superior, to that of OLEDs made with an ITO anode.     

High-resistivity sol-gel ITO thin film as an interfacial buffer layer for bulk heterojunction organic solar cells

Bulk heterojunction organic solar cells have been fabricated by inserting a high-resistivity sol-gel ITO buffer layer between an ITO anode and a PEDOT:PSS hole injection layer. The performance of the devices with the sol-gel ITO atop the ITO anodes treated by conventional annealing at 500 °C for 1 h and rapid thermal process (RTP) at 800 °C for 20 and 30 s was compared. The best power conversion efficiency of 3.5% was achieved for the device with the 15-nm-thick sol-gel ITO treated with RTP at 800 °C for 30 s, as compared with 2.7% of the standard device under an illumination of AM 1.5. In addition, the short circuit current of the device was significantly increased by 42.7%. The observed enhancement of the short circuit current can be attributed an interfacial energy step created by the high-resistivity sol-gel ITO between the ITO anode and the PEDOT:PSS.     

Characteristics of an AlGaInP-Based Light Emitting Diode With an Indium-Tin-Oxide (ITO) Direct Ohmic Contact Structure

An AlGaInP multi-quantum-well (MQW) light-emitting diode (LED) with a direct Ohmic contact structure, formed by an indium-tin-oxide (ITO) transparent film and AuBe diffused thin layer, is fabricated and studied. By the deposition of an AuBe metallic thin layer on the surface of Mg-doped GaP window layer, followed by a thermal activation process, a direct Ohmic contact between ITO and p-GaP layers can be obtained. Experimentally, under an injection current of 20 mA, a dynamic resistance of 5.7 $Omega$ and a forward voltage of 1.91 V, are obtained. In addition, a higher external quantum efficiency of 9.7% and a larger maximum light output power of 26.6 mW are found for the studied LED. As compared with the conventional LED without this structure, the external quantum efficiency of the studied device is increased by 26% under the injection current of 100 mA. This is mainly attributed to the reduced series resistance resulted from the relatively uniform distribution of AuBe atoms near the GaP layer surface and the effective current spreading ability by the use of ITO film. Moreover, the life behavior is not degraded by using this AuBe diffused layer for the studied LED under a 20 mA operation condition.      

Layer‐by‐Layer Assembly of 3D Tissue Constructs with Functionalized Graphene

Carbon‐based nanomaterials have been considered promising candidates to mimic certain structure and function of native extracellular matrix materials for tissue engineering. Significant progress has been made in fabricating carbon nanoparticle‐incorporated cell culture substrates, but only a limited number of studies have been reported on the development of 3D tissue constructs using these nanomaterials. Here, a novel approach to engineer 3D multilayer constructs using layer‐by‐layer (LbL) assembly of cells separated with self‐assembled graphene oxide (GO)‐based thin films is presented. The GO‐based structures are shown to serve as cell adhesive sheets that effectively facilitate the formation of multilayer cell constructs with interlayer connectivity. By controlling the amount of GO deposited in forming the thin films, the thickness of the multilayer tissue constructs could be tuned with high cell viability. Specifically, this approach could be useful for creating dense and tightly connected cardiac tissues through the co‐culture of cardiomyocytes and other cell types. In this work, the fabrication of stand‐alone multilayer cardiac tissues with strong spontaneous beating behavior and programmable pumping properties is demonstrated. Therefore, this LbL‐based cell construct fabrication approach, utilizing GO thin films formed directly on cell surfaces, has great potential in engineering 3D tissue structures with improved organization, electrophysiological function, and mechanical integrity.     

ZnSe/ITO thin films:candidate for CdTe solar cell window layer

The crystal structure, electrical and optical properties of ZnSe thin films deposited on an In₂O₃:Sn (ITO) substrate are evaluated for their suitability as the window layer of CdTe thin film solar cells. ZnSe thin films of 80, 90, and 100 nm thickness were deposited by a physical vapor deposition method on Indium tin oxide coated glass substrates. The lattice parameters are increased to 5.834 Å when the film thickness was 100 nm, which is close to that of CdS. The crystallite size is decreased with the increase of film thickness. The optical transmission analysis shows that the energy gap for the sample with the highest thickness has also increased and is very close to 2.7 eV. The photo decay is also studied as a function of ZnSe film thickness.     

低翘曲度ITO透明导电膜玻璃的工艺研究

研究了不同厚度ITO膜的大尺寸超薄导电玻璃的翘曲度,ITO膜形成期间基片温度对ITO膜层晶体化程度的影响及不同基片温度下形成的ITO膜层在不同的退火条件下的退火前、后的电阻率和膜压应力.实验发现,ITO膜层的很高的压应力是导致导电膜玻璃翘曲的直接原因;采用室温沉积非晶ITO膜,然后经高温热退火可获得低膜压应力多晶相ITO膜.基于实验结论,提出了一种适合批量生产的低翘曲度ITO膜导电玻璃的制备工艺.     

Fabrication of highly efficient blue top-emission organic light-emitting diodes on different reflective electrodes

The performances of top-emission organic light-emitting diodes (TEOLEDs) with various P-dopant (PD) contents in the injection layer were studied by thinning or removing an indium tin oxide (ITO) film sputtered on the anode. On adjusting the thickness of the active TBPDA (N4,N4,N4′,N4′-tetra ([1,1′-biphenyl]-4-yl)-[1,1′-biphenyl]-4,4′-diamine) film used as hole transport layer, the International Commission on Illumination (CIE) coordinates of blue TEOLEDs did not change and the same CIE coordinates (0.14, 0.04) were maintained. The blue index of device I (PD of 3%) without an indium tin oxide (ITO) layer was 139.9 cd/A/CIEy at a current density of 10 mA/cm². This value was 28% higher than that of the device B (PD of 2%), which had a 15-nm thick ITO film, and 19% higher than that of device E (PD of 2%), which had a 7-nm thick ITO film. Devices B, E, and I achieved similar voltages of approximately 3.9 V. Thus, in the optimized TEOLEDs with suitable PD contents, efficiency was improved by silver without the use of ITO as an anode.     

Vertically Aligned Nanocomposite Thin Films as a Cathode/Electrolyte Interface Layer for Thin‐Film Solid Oxide Fuel Cells

A thin layer of a vertically aligned nanocomposite (VAN) structure is deposited between the electrolyte, Ce_0.9Gd_0.1O_1.95 (CGO), and the thin‐film cathode layer, La_0.5Sr_0.5CoO₃ (LSCO), of a thin‐film solid‐oxide fuel cell (TFSOFC). The self‐assembled VAN nanostructure contains highly ordered alternating vertical columns of CGO and LSCO formed through a one‐step thin‐film deposition process that uses pulsed laser deposition. The VAN structure significantly improves the overall performance of the TFSOFC by increasing the interfacial area between the electrolyte and cathode. Low cathode polarization resistances of 9 × 10^?4 and 2.39 Ω were measured for the cells with the VAN interlayer at 600 and 400 °C, respectively. Furthermore, anode‐supported single cells with LSCO/CGO VAN interlayer demonstrate maximum power densities of 329, 546, 718, and 812 mW cm^?2 at 550, 600, 650, and 700 °C, respectively, with an open‐circuit voltage (OCV) of 1.13 V at 550 °C. The cells with the interlayer triple the overall power output at 650 °C compared to that achieved with the cells without an interlayer. The binary VAN interlayer could also act as a transition layer that improves adhesion and relieves both thermal stress and lattice strain between the cathode and the electrolyte.     

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.     

PEN为衬底的柔性有机电致发光器件的光电性能

采用直流磁控溅射技术,在聚对萘二甲酸乙二醇酯(PEN)柔性衬底上制备了氧化物铟锡(ITO)导电薄膜,研究了衬底温度和薄膜厚度工艺参数对柔性衬底上导电薄膜光学性能与电学性能的影响.在优化工艺的条件下,所制备的PEN导电基板的方阻低至35 Ω/□,且可见光透过率大于95％;以此柔性ITO衬底为阳极,制备了结构为PEN/ITO/NPB/Alq3/Al的柔性有机电致发光器件.作为对比,选用多种不同的衬底材料制备了有机电致发光器件,并比较了各器件性能的差异.     

On an AlGaInP-Based Light-Emitting Diode With an ITO Direct Ohmic Contact Structure

An interesting AlGaInP multiple-quantum-well light-emitting diode (LED) with a direct ohmic contact structure, formed by an indium–tin–oxide (ITO) transparent film and AuBe diffused thin layer, is fabricated and studied. The direct ohmic contact structure is performed by the deposition of an AuBe diffused thin layer and the following activation process on the surface of a Mg-doped GaP window layer. Experimental results demonstrate that a dynamic resistance of 5.7 $Omega$ and a forward voltage of 1.91 V, under an injection current of 20 mA, are obtained. In addition, the studied LED exhibits a higher external quantum efficiency of 9.7% and a larger maximum light-output power of 26.6 mW. The external quantum efficiency is increased by 26% under the injection current of 100 mA, as compared with the conventional LED without this structure. This is mainly attributed to the reduced series resistance resulted from the relatively uniform distribution of AuBe atoms near the GaP layer surface and the effective current spreading ability by the use of ITO film. Moreover, the life behavior of the studied LED, under a 20-mA operation condition, is comparable to the conventional LED without this structure.