MPN是感谢主任的奖学金计划提供财政支持。 ，MPN要感谢曾育志与发展的协议，用于太阳能电池加工的帮助。这项工作是在纳米材料研究中心，美国能源部科学办公室，办公室基础能源科学用户设施的合同号DE-AC02-06CH11357。

1。信号采集<ol class="lalpha"><li>安装样品（无阴极聚合物太阳能电池（ITO / PEDOT：PC 61 BM PSS/P3HT））的商业模AFM（Veeco公司，圣巴巴拉，CA）配备了奈米级-V控制器。 </li><li>安装导电原子力显微镜探针原子力显微镜探针持有人模。 </li><li>创建AFM探针，样品和电压源之间的电连接。 </li><li>路线的电流放大器的输出（电流信号），多模AFM偏转输出（力信号），多模的AFM样品高度的输出（距离信号）转换成数字采集卡（NI-PCI-6115数据采集）。收益飞秒DLPCA-200电流放大器是从1 nA / V在50 kHz带宽。 </li><li>适用于6V的偏置AFM探针和ITO电极之间。 </li><li>运行多模AFM在PeakForceTM模式收集地形信号：峰值力设定点30 nN的，支撑振荡幅度为300nm，支撑振荡频率为2 kHz，1赫兹的扫描速率下，和一个resoluti对512 x 512像素。 </li><li> D节中列出的LabVIEW / MATLAB的控制，同时采集的地形地貌信号（步骤e）的收集信号。 </li></ol> 2。数据分析第1步：生成的拉脱力，接触刚度，与当前的地图<ol class="lalpha"><li>阅读时间戳记目前，力和距离的信号到MATLAB中。 </li><li>创建2000力 - 距离，力 - 电流曲线的第一扫描线。的曲线数量是支持振荡频率和扫描速度的函数。 </li><li>从每一个力-距离曲线，确定接触刚度和拉断力戒断期间的原子力显微镜探针（ 图1）。 </li><li>来自每个力-电流曲线，确定的平均电流而AFM探针在撤回（ 图1）是在与表面接触。 </li><li>插值2000等距接触刚度，拉断力，和匹配的分辨率由512点到当前点重刑地形信号。接触刚度，拉脱力，及当前地图的第一扫描线完成。 </li><li>创建接触刚度，拉断力，和当前的地图通过电子邮件512次重复步骤b。结果示于图2。 </li></ol> 3。数据分析第2步：消除区域联系的文物<ol class="lalpha"><li>使用等式（1）和（2），得到的杨氏模量（E 材料 ）和电阻率（ρ）的材料在每个点的扫描：20 <img alt="式（1）" fo:content-width="2.853in" fo:src="/files/ftp_upload/50293/50293eq1highres.jpg" src="/files/ftp_upload/50293/50293eq1.jpg" /> 使用 F ADH = F PULL - 8 nN的（由于水弯月面之间的原子力显微镜（AFM）和表面的粘附），20接触刚度（十一）和电流（I）的映射;探测电压（V），膜厚度（L），并粘着能量（W =γ 探头 +γ 时珍大号- γ的探头 - 材料 ，γ 探头 -探头材料的表面能，γ 材料 -的样品材料，表面能和γ 探针材料 -材料的样品和探针材料的界面能） 20 </li></ol>

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没有利益冲突的声明。

作为带来了一个焦点上OPV技术的最新突破，功率转换效率（PCE）的有机光伏（OPV）细胞（推在细胞水平的10％）3，在演唱会遵守与高通量和低成本的制造工艺4廉价的大面积的太阳能电池的制造的挑战可能的解决方案。 OPV材料在纳米尺度本质上是不均匀的。 OPV材料的纳米尺度的不均匀性和光电器件的性能有着密切的联系。因此，了解成分不均匀性，以及OPV材料的电性能OPV技术向前发展是极为重要的。自1986年以来已经发展成为原子力显微镜（AFM）表面形貌的高精度测量的工具。如今，技术材料的性能（杨氏模量，功能6-10工作，11行为ivity 13日至15日，12机电，等）的测量，正吸引着越来越多的关注。在OPV材料的情况下，本地的物相组成和电性能的相关性，揭示更好地了解有机太阳能电池的内部运作带来了希望。1，16-17基于原子力显微镜的高分辨率相技术能够归属8作为电性能，在聚合材料中的映射。因此，在原则上，聚合物相组合物（通过机械测量）18和电气性能的相关性的是可以使用基于AFM的技术。许多基于AFM的技术，材料的机械和电气性能的测量使用AFM探针和表面之间的接触面积不变的假设。这种假设经常失败，从而导致表面形貌之间的强相关性与机械/电气性能。最近，一种新的原子力显微镜为基础的技术高通量测量的机械的属性（PeakForce）19。 PeakForce的金枪鱼（变化的PeakForce方法）提供了一个平台，同时测量的样品的机械和电气性能。然而，PeakForce金枪鱼方法生产的机械和电气性能的地图，这通常是密切相关的，因为在测量过程中的接触下落不明变异。在本文中，我们提出了一个实验性协议，用于删除相关性，与不同的接触半径利用原子力显微镜的机械和电气性能，同时保持精确的测量。实现材料的电阻和杨氏模量的定量测量结果的协议。

<table border="1"><tbody><tr><td> 的试剂/材料名称 </td><td> 公司 </td><td> 目录编号 </td><td> 评论 </td></tr><tr><td> Plextronics公司的油墨</td><td> Plexcore </td><td> PV 1000 </td><td></td></tr><tr><td> ITO膜的玻璃基板</td><td>台达技术公司</td><td></td><td> 25欧姆/平方</td></tr><tr><td> 30 MHz的合成函数发生器</td><td> Stanfor研究系统</td><td> DS345 </td><td></td></tr><tr><td>电流放大器</td><td>飞秒</td><td> DLPCA-200 </td><td></td></tr><tr><td>多模原子力显微镜</td><td> Veeco公司，圣巴巴拉，CA </td><td></td><td>配备了奈米级-V控制器</td></tr><tr><td>数据采集​​卡</td><td>美国国家仪器公司</td><td> NI PCI-6115 </td><td></td></tr><tr><td>金属Pt探针</td><td> RMNano </td><td> 12Pt3008 </td><td></td></tr><tr><td> MATLAB软件</td><td> Mathworks公司</td><td></td><td></td></tr><tr><td> LabVIEW软件</td><td>美国国家仪器公司</td><td></td><td></td></tr></tbody></table>

concurrent quantitative conductivity and mechanical properties measurements of organic photovoltaic materials using afm

有机光伏（OPV）材料在纳米尺度本质上是不均匀的。纳米非均匀性，OPV材料的影响，光伏设备的性能。因此，了解空间组成的变化以及OPV材料的电性能向前推动光伏技术是极为重要的。1,2在本文中，我们描述了协议的OPV材料的电气和机械性能的定量测量子-100纳米的分辨率。目前，材料的性能进行测量，用市售基于AFM的的技术（PeakForce，导电AFM），一般只提供定性信息。与文献数据的值性以及杨氏模量测定，用我们的方法对典型的ITO / PEDOT：PSS/P3HT：PC 61 BM系统有很好的对应。 P3HT：PC 61 BM的混合分离到PC 61 BM丰富和P3HT丰富的domai纳秒。的PC 61 BM丰富和P3HT丰富域的机 ​​械性能是不同的，它允许为域归属的膜的表面上。更重要的是，机械和电气的数据相结合，允许相关的域结构的表面上的膜的膜的厚度通过测量与电性能变化。

上述的杨氏模量和电阻率的映射（ 图3）本典型的测量结果。机械和电气性能的ITO / PEDOT：PSS/P3HT：PC 61 BM堆栈测定在负（-10 V）和正极（6 V）的电压施加到AFM探针。与静电相互作用的原子力显微镜探针与样品的成像伪影，利用原子力显微镜定量测量的功能特性，是一种常见的问题。在不同电压下的相似性测量的杨氏模量大小演示静电工件相对于如上所述的测量协议的鲁棒性。?...

Watch this Scientific Journal Video about Concurrent Quantitative Conductivity and Mechanical Properties Measurements of Organic Photovoltaic Materials using AFM at JoVE.com

Concurrent Quantitative Conductivity and Mechanical Properties Measurements of Organic Photovoltaic Materials using AFM

有机光伏（OPV）材料在纳米尺度本质上是不均匀的。纳米非均匀性，OPV材料的影响，光伏设备的性能。在本文中，我们描述了一个协议，用于低于100纳米的分辨率OPV材料的电气和机械性能的定量测量。

并行定量的导电性和力学性能测试的有机光伏材料利用原子力显微镜

Organic photovoltaic  (OPV) materials are inherently inhomogeneous at the nanometer scale. Nanoscale  inhomogeneity of OPV materials affects performance ...

concurrent-quantitative-conductivity-mechanical-properties

Research

JoVE Journal

Engineering

11.6K 次观看.  Argonne National Laboratory. 有机光伏（OPV）材料在纳米尺度本质上是不均匀的。纳米非均匀性，OPV材料的影响，光伏设备的性能。在本文中，我们描述了一个协议，用于低于100纳米的分辨率OPV材料的电气和机械性能的定量测量。

视频: Concurrent Quantitative Conductivity and Mechanical Properties Measurements of Organic Photovoltaic Materials using AFM

Controlling the Size, Shape and Stability of Supramolecular Polymers in Water

For aqueous based supramolecular polymers, the simultaneous control over shape, size and stability is very difficult1. At the same time, the ability to do so is highly important in view of a number of applications in functional soft matter including electronics, biomedical engineering, and sensors. In the past, successful strategies to control the size and shape of supramolecular polymers typically focused on the use of templates2,3, end cappers4 or selective solvent techniques5. 
Here we disclose a strategy based on self-assembling discotic amphiphiles that leads to the control over stack length and shape of ordered, chiral columnar aggregates. By balancing electrostatic repulsive interactions on the hydrophilic rim and attractive non-covalent forces within the hydrophobic core of the polymerizing building block, we manage to create small and discrete spherical objects6,7. Increasing the salt concentration to screen the charges induces a sphere-to-rod transition. Intriguingly, this transition is expressed in an increase of cooperativity in the temperature-dependent self-assembly mechanism, and more stable aggregates are obtained. 
For our study we select a benzene-1,3,5-tricarboxamide (BTA) core connected to a hydrophilic metal chelate via a hydrophobic, fluorinated L-phenylalanine based spacer (Scheme 1). The metal chelate selected is a Gd(III)-DTPA complex that contains two overall remaining charges per complex and necessarily two counter ions. The one-dimensional growth of the aggregate is directed by &pi;-&pi; stacking and intermolecular hydrogen bonding. However, the electrostatic, repulsive forces that arise from the charges on the Gd(III)-DTPA complex start limiting the one-dimensional growth of the BTA-based discotic once a certain size is reached. At millimolar concentrations the formed aggregate has a spherical shape and a diameter of around 5 nm as inferred from 1H-NMR spectroscopy, small angle X-ray scattering, and cryogenic transmission electron microscopy (cryo-TEM). The strength of the electrostatic repulsive interactions between molecules can be reduced by increasing the salt concentration of the buffered solutions. This screening of the charges induces a transition from spherical aggregates into elongated rods with a length &gt; 25 nm. Cryo-TEM allows to visualise the changes in shape and size. In addition, CD spectroscopy permits to derive the mechanistic details of the self-assembly processes before and after the addition of salt. Importantly, the cooperativity -a key feature that dictates the physical properties of the produced supramolecular polymers- increases dramatically upon screening the electrostatic interactions. This increase in cooperativity results in a significant increase in the molecular weight of the formed supramolecular polymers in water.

The goal of this experiment is to determine and control the size, shape and stability of self-assembled discotic amphiphiles in water. For aqueous based supramolecular polymers such level of control is very difficult. We apply a strategy using both repulsive and attractive interactions. The experimental techniques applied to characterize this system are broadly applicable.

控制的大小，形状和稳定性超分子聚合物在水

For aqueous based supramolecular polymers, the simultaneous control over shape, size and stability is very difficult1. At the same time, the ability to do ...

科研

工程学

Micro 3D Printing Using a Digital Projector and its Application in the Study of Soft Materials Mechanics

Buckling is a classical topic in mechanics. While buckling has long been studied as one of the major structural failure modes1, it has recently drawn new attention as a unique mechanism for pattern transformation. Nature is full of such examples where a wealth of exotic patterns are formed through mechanical instability2-5. Inspired by this elegant mechanism, many studies have demonstrated creation and transformation of patterns using soft materials such as elastomers and hydrogels6-11. Swelling gels are of particular interest because they can spontaneously trigger mechanical instability to create various patterns without the need of external force6-10. Recently, we have reported demonstration of full control over buckling pattern of micro-scaled tubular gels using projection micro-stereolithography (P&mu;SL), a three-dimensional (3D) manufacturing technology capable of rapidly converting computer generated 3D models into physical objects at high resolution12,13. Here we present a simple method to build up a simplified P&mu;SL system using a commercially available digital data projector to study swelling-induced buckling instability for controlled pattern transformation.
A simple desktop 3D printer is built using an off-the-shelf digital data projector and simple optical components such as a convex lens and a mirror14. Cross-sectional images extracted from a 3D solid model is projected on the photosensitive resin surface in sequence, polymerizing liquid resin into a desired 3D solid structure in a layer-by-layer fashion. Even with this simple configuration and easy process, arbitrary 3D objects can be readily fabricated with sub-100 &mu;m resolution.
This desktop 3D printer holds potential in the study of soft material mechanics by offering a great opportunity to explore various 3D geometries. We use this system to fabricate tubular shaped hydrogel structure with different dimensions. Fixed on the bottom to the substrate, the tubular gel develops inhomogeneous stress during swelling, which gives rise to buckling instability. Various wavy patterns appear along the circumference of the tube when the gel structures undergo buckling. Experiment shows that circumferential buckling of desired mode can be created in a controlled manner. Pattern transformation of three-dimensionally structured tubular gels has significant implication not only in mechanics and material science, but also in many other emerging fields such as tunable matamaterials.

We demonstrate controlled pattern transformation of swelling gel tubes by elastic instability. A simple projection micro stereo-lithography setup is built using an off-the-shelf digital data projector to fabricate three-dimensional polymeric structures in a layer-by-layer fashion. Swelling hydrogel tubes under mechanical constraint display various circumferential buckling modes depending on dimension.

微三维打印使用数字投影机和软材料力学的研究及其应用

Buckling is a classical topic in mechanics. While buckling has long been studied as one of the major structural failure modes1, it has recently drawn new ...

Using Neutron Spin Echo Resolved Grazing Incidence Scattering to Investigate Organic Solar Cell Materials

The spin echo resolved grazing incidence scattering (SERGIS) technique has been used to probe the length-scales associated with irregularly shaped crystallites. Neutrons are passed through two well defined regions of magnetic field; one before and one after the sample. The two magnetic field regions have opposite polarity and are tuned such that neutrons travelling through both regions, without being perturbed, will undergo the same number of precessions in opposing directions. In this case the neutron precession in the second arm is said to &#34;echo&#34; the first, and the original polarization of the beam is preserved. If the neutron interacts with a sample and scatters elastically the path through the second arm is not the same as the first and the original polarization is not recovered. Depolarization of the neutron beam is a highly sensitive probe at very small angles (&#60;50&#160;&#956;rad) but still allows a high intensity, divergent beam to be used. The decrease in polarization of the beam reflected from the sample as compared to that from the reference sample can be directly related to structure within the sample.
In comparison to scattering observed in neutron reflection measurements the SERGIS signals are often weak and are unlikely to be observed if the in-plane structures within the sample under investigation are dilute, disordered, small in size and polydisperse or the neutron scattering contrast is low. Therefore, good results will most likely be obtained using the SERGIS technique if the sample being measured consist of thin films on a flat substrate and contain scattering features that contains a high density of moderately sized features (30 nm to 5 &#181;m) which scatter neutrons strongly or the features are arranged on a lattice. An advantage of the SERGIS technique is that it can probe structures in the plane of the sample.

Progress has been made in utilizing spin echo resolved grazing incidence scattering (SERGIS) as a neutron scattering technique to probe the length-scales in irregular samples. Crystallites of [6,6]-phenyl-C61-butyric acid methyl ester have been probed using the SERGIS technique and the results confirmed by optical and atomic force microscopy.

使用中子自旋回声解决放牧发生率散射调查有机太阳能电池材料

The spin echo resolved grazing incidence scattering (SERGIS) technique has been used to probe the length-scales associated with irregularly shaped ...

Characterization of Thermal Transport in One-dimensional Solid Materials

The TET (transient electro-thermal) technique is an effective approach developed to measure the thermal diffusivity of solid materials, including conductive, semi-conductive or nonconductive one-dimensional structures. This technique broadens the measurement scope of materials (conductive and nonconductive) and improves the accuracy and stability. If the sample (especially biomaterials, such as human head hair, spider silk, and silkworm silk) is not conductive, it will be coated with a gold layer to make it electronically conductive. The effect of parasitic conduction and radiative losses on the thermal diffusivity can be subtracted during data processing. Then the real thermal conductivity can be calculated with the given value of volume-based specific heat (&#961;cp), which can be obtained from calibration, noncontact photo-thermal technique or measuring the density and specific heat separately. In this work, human head hair samples are used to show how to set up the experiment, process the experimental data, and subtract the effect of parasitic conduction and radiative losses.

The TET (transient electro-thermal) technique is an effective approach developed to measure the thermal diffusivity of solid materials.

在一维固体材料的热传输的特性

The TET (transient electro-thermal) technique is an effective approach developed to measure the thermal diffusivity of solid materials, including ...

Using Microwave and Macroscopic Samples of Dielectric Solids to Study the Photonic Properties of Disordered Photonic Bandgap Materials

Recently, disordered photonic materials have been suggested as an alternative to periodic crystals for the formation of a complete photonic bandgap (PBG). In this article we will describe the methods for constructing and characterizing macroscopic disordered photonic structures using microwaves. The microwave regime offers the most convenient experimental sample size to build and test PBG media. Easily manipulated dielectric lattice components extend flexibility in building various 2D structures on top of pre-printed plastic templates. Once built, the structures could be quickly modified with point and line defects to make freeform waveguides and filters. Testing is done using a widely available Vector Network Analyzer and pairs of microwave horn antennas. Due to the scale invariance property of electromagnetic fields, the results we obtained in the microwave region can be directly applied to infrared and optical regions. Our approach is simple but delivers exciting new insight into the nature of light and disordered matter interaction.

Our representative results include the first experimental demonstration of the existence of a complete and isotropic PBG in a two-dimensional (2D) hyperuniform disordered dielectric structure. Additionally we demonstrate experimentally the ability of this novel photonic structure to guide electromagnetic waves (EM) through freeform waveguides of arbitrary shape.

Disordered structures offer new mechanisms for forming photonic bandgaps and unprecedented freedom in functional-defect designs. To circumvent the computational challenges of disordered systems, we construct modular macroscopic samples of the new class of PBG materials and use microwaves to characterize their scale-invariant photonic properties, in an easy and inexpensive manner.

利用微波和电介质固体的宏观样本，研究无序光子带隙材料的光子特性

Recently, disordered photonic materials have been suggested as an alternative to periodic crystals for the formation of a complete photonic bandgap (PBG). ...

Preparation and Friction Force Microscopy Measurements of Immiscible, Opposing Polymer Brushes

Solvated polymer brushes are well known to lubricate high-pressure contacts, because they can sustain a positive normal load while maintaining low friction at the interface. Nevertheless, these systems can be sensitive to wear due to interdigitation of the opposing brushes. In a recent publication, we have shown via molecular dynamics simulations and atomic force microscopy experiments, that using an immiscible polymer brush system terminating the substrate and the slider surfaces, respectively, can eliminate such interdigitation. As a consequence, wear in the contacts is reduced. Moreover, the friction force is two orders of magnitude lower compared to traditional miscible polymer brush systems. This newly proposed system therefore holds great potential for application in industry. Here, the methodology to construct an immiscible polymer brush system of two different brushes each solvated by their own preferred solvent is presented. The procedure how to graft poly(N-isopropylacrylamide) (PNIPAM) from a flat surface and poly(methyl methacrylate) (PMMA) from an atomic force microscopy (AFM) colloidal probe is described. PNIPAM is solvated in water and PMMA in acetophenone. Via friction force AFM measurements, it is shown that the friction for this system is indeed reduced by two orders of magnitude compared to the miscible system of PMMA on PMMA solvated in acetophenone.

The methodology to perform friction force microscopy experiments for contacting brushes is presented: Two polymer brushes that are grafted from (a) substrates and (b) colloidal probes are slid to show that, by using two contacting immiscible brush systems, friction in sliding contacts is reduced compared to miscible brush systems.

互溶的测量准备和摩擦力显微镜，反对聚合物刷

Solvated polymer brushes are well known to lubricate high-pressure contacts, because they can sustain a positive normal load while maintaining low ...

A Testing Platform for Durability Studies of Polymers and Fiber-reinforced Polymer Composites under Concurrent Hygrothermo-mechanical Stimuli

The durability of polymers and fiber-reinforced polymer composites under service condition is a critical aspect to be addressed for their robust designs and condition-based maintenance. These materials are adopted in a wide range of engineering applications, from aircraft and ship structures, to bridges, wind turbine blades, biomaterials and biomedical implants. Polymers are viscoelastic materials, and their response may be highly nonlinear and thus make it challenging to predict and monitor their in-service performance. The laboratory-scale testing platform presented herein assists the investigation of the influence of concurrent mechanical loadings and environmental conditions on these materials. The platform was designed to be low-cost and user-friendly. Its chemically resistant materials make the platform adaptable to studies of chemical degradation due to in-service exposure to fluids. An example of experiment was conducted at RT on closed-cell polyurethane foam samples loaded with a weight corresponding to ~50% of their ultimate static and dry load. Results show that the testing apparatus is appropriate for these studies. Results also highlight the larger vulnerability of the polymer under concurrent loading, based on the higher mid-point displacements and lower residual failure loads. Recommendations are made for additional improvements to the testing apparatus.

The durability of polymers and fiber-reinforced polymer composites in service is a critical aspect for their designs and condition-based maintenance. We present a novel low-cost laboratory testing platform for the investigation of the influence of concurrent mechanical and environmental loadings, and may help design more efficient yet safer composite structures.

一个测试平台为聚合物的耐久性研究，并在同期Hygrothermo机械刺激纤维增强聚合物复合材料

The durability of polymers and fiber-reinforced polymer composites under service condition is a critical aspect to be addressed for their robust designs ...

Quantitative Hardness Measurement by Instrumented AFM-indentation

In this work, a combination of amplitude-modulated non-contact atomic force microscopy and atomic force spectroscopy is applied for instrumented hardness measurements on an Au(111) surface with atomistic resolution of single plasticity events. A careful experimental procedure is described that includes the force sensor selection, its calibration, the calibration of the cantilever deflection detection system, and the minimization of instrumental drift for accurate and reproducible force-distance measurements. Also, a method for the data analysis is presented that allows the extraction of force-penetration curves from recorded force-distance curves. A typical curve displays a clear elastic deformation regime up to the first plasticity event, or pop-in, with a length in the range of one to two Burger's vectors. Later plasticity events exhibit the same magnitude. The work of plasticity is further extracted from the measurements. Finally, the hardness is determined in combination with the indentation curve using non-contact atomic force microscopy images of the remaining indents.

This experimental protocol describes how atomic force microscopy can be used to measure hardness at the true nanometer scale and to detect single atomistic plasticity events.

通过仪表AFM压痕硬度定量测量

In this work, a combination of amplitude-modulated non-contact atomic force microscopy and atomic force spectroscopy is applied for instrumented hardness ...

Recombination Dynamics in Thin-film Photovoltaic Materials via Time-resolved Microwave Conductivity

A method for investigating recombination dynamics of photo-induced charge carriers in thin film semiconductors, specifically in photovoltaic materials such as organo-lead halide perovskites is presented. The perovskite film thickness and absorption coefficient are initially characterized by profilometry and UV-VIS absorption spectroscopy. Calibration of both laser power and cavity sensitivity is described in detail. A protocol for performing Flash-photolysis Time Resolved Microwave Conductivity (TRMC) experiments, a non-contact method of determining the conductivity of a material, is presented. A process for identifying the real and imaginary components of the complex conductivity by performing TRMC as a function of microwave frequency is given. Charge carrier dynamics are determined under different excitation regimes (including both power and wavelength). Techniques for distinguishing between direct and trap-mediated decay processes are presented and discussed. Results are modelled and interpreted with reference to a general kinetic model of photoinduced charge carriers in a semiconductor. The techniques described are applicable to a wide range of optoelectronic materials, including organic and inorganic photovoltaic materials, nanoparticles, and conducting/semiconducting thin films.

A Time Resolved Microwave Conductivity technique for investigating direct and trap-mediated recombination dynamics and determining carrier mobilities of thin film semiconductors is presented here.

通过时间分辨微波电导率重组动力学薄膜光伏材料

A method for investigating recombination dynamics of photo-induced charge carriers in thin film semiconductors, specifically in photovoltaic materials ...

Preparation of Liquid Crystal Networks for Macroscopic Oscillatory Motion Induced by Light

A strategy based on doped liquid crystalline networks is described to create mechanical self-sustained oscillations of plastic films under continuous light irradiation. The photo-excitation of dopants that can quickly dissipate light into heat, coupled with anisotropic thermal expansion and self-shadowing of the film, gives rise to the self-sustained deformation. The oscillations observed are influenced by the dimensions and the modulus of the film, and by the directionality and intensity of the light. The system developed offers applications in energy conversion and harvesting for soft-robotics and automated systems.
The general method described here consists of creating free-standing liquid crystalline films and characterizing the mechanical and thermal effects observed. The molecular alignment is achieved using alignment layers (rubbed polyimide), commonly used in the display manufacturing industry. To obtain actuators with large deformation, the mesogens are aligned and polymerized in a splay/bend configuration, i.e., with the director of the liquid crystals (LCs) going gradually from planar to homeotropic through the film thickness. Upon irradiation, the mechanical and thermal oscillations obtained are monitored with a high-speed camera. The results are further quantified by image analysis using an image processing program.

The goal of the protocol is to create liquid crystalline polymer films that can mechanically oscillate under continuous light irradiation. We describe in great detail the conception of free-standing films, from the liquid crystal alignment method to the photo-actuation. The experimental protocol applied to prepare this material is broadly applicable.

光诱导的宏观振荡运动液晶网络的制备

A strategy based on doped liquid crystalline networks is described to create mechanical self-sustained oscillations of plastic films under continuous ...