Hybrid photovoltaic structures based on amorphous silicon and P3HT:PCBM/PEDOT:PSS polymer semiconductors

Hybrid thin film photovoltaic structures, based on hydrogenated silicon (Si:H), organic poly(3-hexythiophene):methano-fullerenephenyl-C61-butyric-acid-methyl-ester (P3HT:PCBM) and poly(3,4ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) films, have been fabricated. Organic semiconductor thin films were deposited by spin-coating technique and were exposed to radio frequency plasma enhanced chemical vapor deposition (RF PECVD) of Si:H films at deposition temperature T_d = 160 °C. Different types of structures have been investigated: H1) ITO/(p)SiC:H /P3HT:PCBM/(n) Si:H, H2) ITO/PEDOT:PSS/(i)Si:H/(n) Si:H and H3) ITO/PEDOT:PSS/P3HT:PCBM/(i)Si:H/(n)Si:H. Short circuit current density spectral response and current-voltage characteristics were measured for diagnostic of the photovoltaic performance. The current density spectral dependence of hybrid structures which contains organic layers showed improved response (50–80%) in high photon energy range (hν ≈ 3.1–3.5 eV) in comparison with Si:H reference structure. An adjustment in the absorbing layer thickness and in the contact material for ITO/PEDOT:PSS/(i)Si:H/(n)Si:H structure, resulted in a remarkably high short circuit current density (as large as 17.74 mA/cm²), an open circuit voltage of 640 mV and an efficiency of 3.75%.     

Improved efficiency of indium-tin-oxide-free organic light-emitting devices using PEDOT:PSS/graphene oxide composite anode

We have demonstrated an indium-tin-oxide free organic light-emitting device (OLED) with improved efficiency by doping poly (3,4-ethylene dioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) with graphene oxide (GO) as a composite anode. In comparison with a pure PEDOT:PSS anode, 55% enhancement in efficiency has been obtained for the OLEDs based on the PEDOT:PSS/GO composite anode at an optimal condition. The PEDOT:PSS/GO composite anode shows a lower hole-injection barrier, which contributes to the improved device efficiency. Moreover, both high transmittance and good surface morphology similar to that of the pure PEDOT:PSS film also contribute to the enhanced efficiency. It is obvious that composite anode will generally be applicable in organic optoelectronic devices which require smooth and transparent anode.     

Effects of the ink concentration on multi-layer gravure-printed PEDOT:PSS

To date, highly conductive PEDOT:PSS is the most promising transparent electrode for printing-based flexible organic electronics. Spin-coating and slot-die coating have been commonly used for printing this material. Among the roll-to-roll printing processes, gravure is the most promising for manufacturing large area electronics offering the advantages of high speed and high printing definition. However, gravure printing highly conductive PEDOT encounters some technological limitations such as low thickness, layer inhomogeneity and high surface roughness resulting in a layer not suitable as electrode in electronic devices. In order to realize an electrode of highly conductive PEDOT by gravure printing, a multilayer approach with variable ink concentration was tried using IPA as process solvent. Variable solvent amount of overlapped printed layers was found to play an important role in the spreading of the PEDOT ink onto the pre-printed layers and in the smoothing of its existent peaks. In particular, adopting increasing ink dilution with increasing of the overlapped layers, multi-layer gravure-printed highly conductive PEDOT was successfully realized with characteristics suitable as transparent electrode for organic electronic devices (sheet resistance lower than 130 Ω/sq, conductivity higher than 450 S/cm and optical transmittance over 80%). This is the first time that such results were reached by gravure printing technique thanks to the easy proposed approach.     

The influence of a PEDOT:PSS layer on the efficiency of a polymer light-emitting diode

The mutual influence of the constituent layers in a polymer light-emitting diode on the photoluminescence quantum efficiency of the light-emitting polymer is investigated. It is shown that a specific chemical interaction can occur between poly-(3,4-ethylenedioxythiophene):poly-(styrenesulphonic acid) (PEDOT:PSS) and poly-(p-phenylenevinylene) (PPV). It is further shown that PEDOT:PSS has a considerable effect on molecular dopants dispersed in the polymeric host. In the case of PPV the interaction with PEDOT:PSS results in the creation of defect states in an interface region between the PEDOT:PSS layer and the PPV layer. The presence of these defect states results in a considerable quenching of the PPV photoluminescence. For devices based on PPV, already at voltages below the built-in voltage the PEDOT:PSS-induced defect states can be filled with charge carriers, a process that can be monitored with field-dependent photoluminescence measurements and with electrical impedance measurements. Filling of defect states with charge carriers constitutes a dynamic photoluminescence quenching mechanism, that is present in addition to the previously mentioned static quenching mechanism due to the presence of defect states. As a result, the photoluminescence intensity of PPV in a working device under operating conditions can be quenched by at least 20% with respect to the intensity at zero applied volt. To indicate that these effects involve a specific interaction between PEDOT:PSS and PPV, it is shown that the effects are absent in devices based on poly-(2,7-spirofluorene) (PSF) instead of PPV, and that the effects are independent of the type of cathode material. Defect states in PPV can be created through an electrophilic addition reaction involving the PPV vinylene bond and protons from PEDOT:PSS.     

The effect of solvent treatment on the buried PEDOT:PSS layer

Solvent treatment has been widely used to improve the device performance of both Organic Light Emitting Diodes (OLEDs) and Polymer Solar Cells (PSCs). One of the proposed mechanisms is the modification of the buried PEDOT:PSS layer underneath the organic active layer by the permeating solvent. By measuring the lateral electric conductivity of the PEDOT:PSS layer, the 3 orders of magnitude's enhancement on the conductivity after solvent treatment confirms that the solvent permeates through the top organic active layer and modifies the PEDOT:PSS layer. Using a “peel-off” method, the buried PEDOT:PSS layer is fully exposed and studied by UV–vis spectra, XPS spectra, and c-AFM images. The data suggest that the permeating solvent dissolves PSS, changes PEDOT:PSS′ core-shell structure into a linear/coiled structure, and moves PSS from the bulk to the surface. As a result, PEDOT becomes more continuous in the bulk. The continuous conducting PEDOT-rich domains create percolating pathways for the current which significantly improve electric conductivity.     

Explaining the effects of processing on the electrical properties of PEDOT:PSS

By simultaneously measuring the Seebeck coefficient and the conductivity in differently processed PEDOT:PSS films, fundamental understanding is gained on how commonly used processing methods improve the conductivity of PEDOT:PSS. Use of a high boiling solvent (HBS) enhances the conductivity by 3 orders of magnitude, as is well-known. Simultaneously, the Seebeck coefficient S remains largely unaffected, which is shown to imply that the conductivity is improved by enhanced connectivity between PEDOT-rich filaments within the film, rather than by improved conductivity of the separate PEDOT filaments. Post-treatment of PEDOT:PSS films by washing with H₂SO₄ leads to a similarly enhanced conductivity and a significant reduction in the layer thickness. This reduction strikingly corresponds to the initial PSS ratio in the PEDOT:PSS films, which suggests removal and replacement of PSS in PEDOT:PSS by HSO₄⁻ or SO₄²⁻ after washing. Like for the HBS treatment, this improves the connectivity between PEDOT filaments. Depending on whether the H₂SO₄ treatment is or is not preceded by an HBS treatment also the intra-filament transport is affected. We show that by characterization of S and σ it is possible to obtain more fundamental understanding of the effects of processing on the (thermo)electrical characteristics of PEDOT:PSS.     

Influence of PEDOT:PSS buffer layer on the performance of organic photocoupler

We have fabricated an organic photocoupler with organic light-emitting diodes （OLEDs） with 520 nm emissive wavelength as the input light source and a photodiode （PD） based on poly（3-hexylthiophene） （P3HT）：1-（3-methoxycarbonyl）propyl- 1-phenyl-（6,6）-C61 （PCBM） as the detector. The influences of buffer layer （PEDOT：PSS） on output current （Iout）, current transfer ratio （CTR） and time response characteristics of the photocoupler device were studied. Through our experiments, It is found that the output current linearly increases with the input current, the max output current and CTR of the devices with PEDOT：PSS buffer layer are 2 times and 7 times than that of the devices without buffer layer respectively, which show that the existence of buffer layer can enhance the output photocurrent efficiently. Moreover, the existence of PEDOT：PSS eliminates the time delay of the devices.     

以绝缘体上硅为基底的平面膜片钳电极的设计和制作

The planar patch-clamp technique has been applied to high throughput screening in drug discovery. The key feature of this technique is the fabrication of a planar patch-clamp substrate using appropriate materials. In this study, a planar patch-clamp substrate was designed and fabricated using a silicon-on-insulator （SOI） wafer. The access resistance and capacitance of SOl-based planar patch-clamp substrates are smaller than those of bulk silicon-based planar substrates, which will reduce the distributed RC noise.     

Design and fabrication of a planar patch-clamp substrate using a silicon-on-insulator wafer

noise.     

基于PEDOT:PSS掺杂MoO3修饰有机电致发光器件性能的研究

有机电致发光器件因具有质量轻、亮度高、柔性 、宽视角和响应速度快等优点已经成 为下一代平板显示和照明领域的潜在主流技术。本文证实了MoO₃掺杂于PEDOT:PSS作为空 穴注入 层时,可以改善器件性能。与未掺杂器件相比,掺杂器件的亮度和效率显著提高,启亮电压 降低0.5 V。AFM,透光性和单空穴器件实验表明,当在ITO和空穴传 输层之间插入PEDOT:PSS :MoO₃后,由于修饰了ITO表面膜形貌,增加了绿光区透光性以及降低了空穴注入层电阻 从而提高了器件的性能。     

基于石英衬底的16通道二氧化硅可调复用器/解复用器的单片集成

本文是关于可调复用器/解复用器的单片集成,它由一个16通道200 GHZ的二氧化硅阵列波导光栅和一组马赫增德尔干涉型热光可调光衰减器阵列构成。该集成器件是基于石英衬底的,与基于硅衬底的器件相比,省去了沉积下包层的工艺步骤,并且降低了器件功耗。该集成器件的插入损耗是-5 dB,串扰小于-22 dB。在衰减为20 dB的时候每个通道的功耗只有110 mW。     

Reducing the contact resistance in organic thin-film transistors by introducing a PEDOT:PSS hole-injection layer

We coated gold electrodes with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) in order to reduce the contact resistance in pentacene organic field-effect transistors (OFETs). The crystallinity of the pentacene layers on the gold electrodes was found to increase upon coating the substrates with PEDOT:PSS, whereas the hole-injection barrier between the organic semiconductor and the metal electrode decreased from 0.85 to 0.14 eV. The increased crystallinity and reduced hole-injection barrier resulted in a significant reduction of the contact resistance in the pentacene OFETs, thus leading to an improvement of the field-effect mobility of the devices (from 0.031 to 0.218 cm²/Vs).     

激光诱导等离子体加工石英微通道的研究

为了在熔融石英基体内制作出高质量的微通道,分别用调Q的Nd:YAG脉冲激光器输出的基频光(1064nm)和经过倍频晶体后的混合光(倍频光为70%,基频光为30%)辐照熔融石英玻璃,通过诱导等离子体加工微通道,并初步分析了基频光与混合光加工产生差别的原因。结果表明,用混合光加工的通道内壁较光滑,加工速度快,所加工的通道最深达8mm。     

A Model for the Current–Voltage Characteristics of ITO/PEDOT:PSS/MEH-PPV/Al Photodetectors

We have developed a model of current-voltage (I-V) characteristic for an ITO/PEDOT:PSS/MEH-PPV/Al photodetector. The model is based on the solution of the continuity and drift-diffusion equation for hole polarons. Detailed analysis of the generation process is carried out through the investigation of the internal quantum efficiency (QE) dependence on incident photon flux density, incident light wavelength, and applied electric field. An excellent agreement between the simulated and measured I-V characteristics has been achieved in the maximum external QE wavelength range of the photodetector for a wide range of bias voltages from 0 to -8 V.     

Simultaneous enhancement of the efficiency and stability of organic solar cells using PEDOT:PSS grafted with a PEGME buffer layer

We report a simple processing method to simultaneously improve the efficiency and stability of organic solar cells (OSCs). Poly(4-styrene sulfonate)-doped poly(3,4-ethylenedioxy-thiophene (PEDOT:PSS), widely used as hole transport layer (HTL) in OSCs, tends to accelerate the degradation of devices because of its hygroscopic and acidic properties. In this regard, we have modified PEDOT:PSS to reduce its hygroscopic and acidic properties through a condensation reaction between PEDOT:PSS and poly(ethylene glycol) methyl ether (PEGME) in order to improve the efficiency and stability of OSCs. As a result, the power conversion efficiency (PCE) increased by 21%, from 2.57% up to 3.11%. A better energy level alignment by the reduced work function of the modified PEDOT:PSS with a highest occupied molecular orbital (HOMO) level of poly(3-hexylthiophene-2,5-diyl) (P3HT) is considered the origin of the improved the efficiency. The half-life of OSCs with PEDOT:PSS modified with PEGME buffer layer also increased up to 3.5 times compared to that of devices with pristine PEDOT:PSS buffer layer.     

Enhancement of organic solar cell efficiency by patterning the PEDOT:PSS hole transport layer using nanoimprint lithography

In order to improve the conversion efficiency of organic photovoltaic (OPV) cells, nano-patterned poly (3,4-ethylenedioxythiophene) poly (styrenesulfonate) (PEDOT:PSS) was used as a hole transfer layer (HTL). Using nanoimprint lithography, a process that is easily applied to large-area substrates, a spherical array of PEDOT:PSS droplets was formed. The effect of the PEDOT:PSS nanostructure was characterized by optical and electrical measurements. Because the hemispherical array of PEDOT:PSS scatters light efficiently, absorption of the incident light increases when the nanostructured layer is employed. The conversion efficiency of the nano-patterned OPV cells is 25% larger than that of non-patterned OPV cells, due to the increase in short-circuit current (J_sc).     

Toward Stretchable Self‐Powered Sensors Based on the Thermoelectric Response of PEDOT:PSS/Polyurethane Blends

The development of new flexible and stretchable sensors addresses the demands of upcoming application fields like internet‐of‐things, soft robotics, and health/structure monitoring. However, finding a reliable and robust power source to operate these devices, particularly in off‐the‐grid, maintenance‐free applications, still poses a great challenge. The exploitation of ubiquitous temperature gradients, as the source of energy, can become a practical solution, since the recent discovery of the outstanding thermoelectric properties of a conductive polymer, poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate) (PEDOT:PSS). Unfortunately the use of PEDOT:PSS is currently constrained by its brittleness and limited processability. Herein, PEDOT:PSS is blended with a commercial elastomeric polyurethane (Lycra), to obtain tough and processable self‐standing films. A remarkable strain‐at‐break of ≈700% is achieved for blends with 90 wt% Lycra, after ethylene glycol treatment, without affecting the Seebeck voltage. For the first time the viability of these novel blends as stretchable self‐powered sensors is demonstrated.     

Improved performance of perovskite solar cells with a TiO2/MoO3 core/shell nanoparticles doped PEDOT:PSS hole-transporter

We demonstrate improved performance of inverted planar heterojunction CH₃NH₃PbI_3-xCl_x perovskite solar cells with a TiO₂/MoO₃ core/shell nanoparticles (NPs) doped poly(3,4-ethylene dioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) hole-transporting layer (HTL). TiO₂/MoO₃ Core/shell NPs with size of approximately 40 nm are successfully prepared with a simple wet solution method and are interspersed into PEDOT: PSS layer to construct the HTL. The optimized device shows a high power conversion efficiency of 13.63%, which is dramatically improved compared with the reference device with a pristine PEDOT:PSS HTL. The improvement is mainly attributed to the increased crystalline of the CH₃NH₃PbI_3-xCl_x film with large-scale domains and a compact morphology. More interesting, the cells exhibit superior stability in ambient conditions, which is attributed to the inhibited penetration of moisture due to the compact morphology of the CH₃NH₃PbI_3-xCl_x film and the reduced hygroscopicity of the PEDOT:PSS film.     

基于石英基片的二毫米波段二次谐波混频器设计和研制

介绍了一种基于石英基片的2mm波段二次谐波混频器.阐述了谐波混频器的基本原理,建立了混频二极管对结构的高频模型,并用全波分析软件对整个电路进行了仿真优化.实测得到射频信号在116～120GHz范围内,当本振频率为59GHz、功率为7～14dBm时,最低变频损耗为17dB,最高变频损耗为20dB.混频器的P1dB为1dB...     

Characteristics and fabrication of nanohole array on InP semiconductor substrate using nanoporous alumina

Uniform arrays of nano-sized pore produced in porous alumina were transferred into InP substrates by inductively coupled plasma reactive ion etching (ICP-RIE). We observed a significant enhancement in the light output from InP substrate with nanohole arrays on the surface. Photoluminescence intensity of triangular arrays of air cylinders on InP substrate showed an enhancement up to 3 times compared with that from a raw InP substrate without such structure. The ICP-RIE technique using nanoporous alumina mask can be used as a prospective method in the fabrication of nanostructure materials for increasing the light output from semiconductor light emitting devices.