PEDOT∶PSS及其纳米复合材料热电性质的研究进展

近年来,随着能源危机的加剧,可以将热能与电能进行直接转换的热电材料得到了广泛的关注。在众多热电材料体系中,有机无机纳米复合热电材料具有独特优势。相比于无机材料,有机材料成本低、质量轻、机械柔韧性好、热导率较低。添加不同类型的添加材料构成纳米复合材料后,额外引入的声子-界面散射能进一步降低热导率,同时有机无机材料能带不匹配引起的载流子筛选效应进一步提升塞贝克(Seebeck)系数。因此,目前大量工作证明有机无机纳米复合热电材料有潜力获得高的热电优值(Figure of merit,ZT),在微型热电制冷器件、柔性可穿戴发电设备、温度传感器等领域均具有光明的应用前景。本文聚焦聚(3, 4-乙烯二氧噻吩)∶聚(苯乙烯磺酸盐)(PEDOT∶PSS)热电材料及以其为基底构成的纳米复合材料热电性能的研究工作,综述了提升PEDOT∶PSS热电性能的物理方法、化学试剂改性法等。进一步重点讨论了加入不同类型的无机填料的PEDOT∶PSS基纳米复合材料热电性质的研究进展,并揭示了其热电性能提升的内在机制。     

电化学沉积法制备PEDOT/PEDOT∶PSS基柔性纳米纤维膜及其热电性能

通过静电纺丝技术制备柔性热电薄膜是一种非常可行的方法,制得的纳米纤维会随机交叉排列形成多孔结构。该结构不仅可以增强薄膜的变形能力、柔性和延展性,还可以增加纳米纤维膜中低热导率的非流动空气的含量,有利于降低纳米纤维膜的导热系数,然而目前对于静电纺丝在柔性热电领域应用的相关研究非常少。本工作通过静电纺丝技术制备了具有良好自支撑性和柔性的聚(3,4-乙烯二氧噻吩)∶聚对苯乙烯磺酸钠(PEDOT∶PSS)基纳米纤维膜,并结合电化学聚合法在该纳米纤维表面沉积了PEDOT导电层,得到了PEDOT/PEDOT∶PSS基热电纳米纤维膜。研究发现,聚合电位和单体浓度对热电纳米纤维膜的导电率有很大影响,最终在聚合电位为1. 5 V、单体浓度为0. 03 mol/L时,电导率和塞贝克系数分别为9. 582 S·cm~(-1)和26. 7μV·K~(-1),最优PF值可达0. 68μW·m~(-1)·K~(-2)。     

提高聚(3,4-乙撑二氧噻吩)∶聚苯乙烯磺酸电导率的最新研究进展

随着能源危机和环境污染问题的日益严峻,近年来热电材料的研究越来越受到人们的关注。聚(3,4-乙撑二氧噻吩)∶聚苯乙烯磺酸(PEDOT∶PSS)被认为是热电性能最好的有机热电材料之一。PEDOT∶PSS具备好的成膜性、高的透明性、优异的电导可控性以及热稳定性。系统地综述了提高PEDOT∶PSS电导率的一些物理、化学方法,探讨了其电导率增强的机理以及介绍了其目前最新的应用情况。预期未来具有高电导率和高透明性的PEDOT∶PSS薄膜材料的研究将得到突破性发展。     

反离子聚合聚(3,4-乙烯二氧噻吩)薄膜的热电性能研究进展EI北大核心CSCD

反离子的选择对电化学聚合聚(3,4-乙烯二氧噻吩)(PEDOT)薄膜的结构和热电性能的影响备受关注,在已报道的聚合物薄膜中,PEDOT:聚(苯乙烯磺酸盐)(PSS)、PEDOT:甲苯磺酸盐(Tos)、PEDOT:高氯酸(ClO_(4))和PEDOT:三氟甲磺酸酯(OTf)等被广泛研究。文中综合分析了不同类型反离子对PEDOT薄膜热电性能的应用研究,重点阐述了PEDOT:PSS和PEDOT:Tos提高热电性能的工艺方法,PEDOT:PSS薄膜具有高电导率、可水处理和热稳定性高等特点,二次掺杂、化学去掺杂和连续处理工艺能有效提高其热电性能,但是PSS有亲水性的限制;而Tos具有疏水性,且PEDOT:Tos薄膜能够有效平衡赛贝克系数和电导率的关系;其它的PEDOT:ClO_(4)和PEDOT:OTf等薄膜对热电性能也起到了一定的促进作用。最后,展望了反离子聚合PEDOT薄膜作为柔性热电器件和可穿戴电子器件的开发和实际应用。对进一步研究新的反离子聚合具有一定的参考价值。     

还原氧化石墨烯/聚3,4-二氧乙烯噻吩∶聚苯乙烯磺酸柔性透明导电薄膜的制备及表征

采用HI整体还原法将原位聚合法制备出的氧化石墨烯/聚3,4-二氧乙烯噻吩∶聚苯乙烯磺酸(GO/PEDOT∶PSS)复合薄膜还原成还原氧化石墨烯/PEDOT∶PSS(RGO/PEDOT∶PSS)复合薄膜。通过X射线衍射、拉曼光谱、扫描电镜、四探针测试仪和紫外分光光度仪等手段对所制备材料的性能进行了表征。结果表明:当RGO掺杂量为15%(质量分数)时,RGO/PEDOT∶PSS复合薄膜综合性能最优,其方块电阻为0.25kΩ/□,透光率达到85.2%(λ=550nm),同时具有优良的导电性和柔性。     

上海硅酸盐所在有机-无机复合热电材料领域取得重要进展

正近日,中国科学院上海硅酸盐研究所陈立东研究员、姚琴副研究员的研究团队在聚3,4-乙烯二氧噻吩(PEDOT)基有机/无机复合热电材料领域取得重要进展。该团队采用新型氧化剂,通过自抑制聚合法,获得了高膜厚无气孔PEDOT∶DBSA-Te量子点复合热电薄膜。研究团队首先通过设计调控导电高分子对阴离子的分子结构来调控对阴离子的位阻,实现了薄膜自抑制法聚合     

Si/PEDOT:PSS杂化太阳能电池的研究进展

硅有机/无机杂化太阳能电池结合了硅材料载流子迁移率高的优势,以及有机物的材料易合成、光电特性可调的特点,具有制备工艺简单、成本低以及柔性等适合未来应用发展的潜力特征。在介绍硅基杂化太阳能电池的基本结构和工作原理的基础上,从硅基材料的优化、有机导电聚合物PEDOT∶PSS改性、硅与PEDOT∶PSS界面修饰和结构优化,以及杂化太阳能电池的稳定性4个方面概况了近期的研究进展,重点针对Si/PEDOT∶PSS杂化太阳能电池结构优化及性能改进方面的最新研究热点,分析了当前硅基杂化电池发展的问题,指出了Si/PEDOT∶PSS杂化太阳能电池的发展方向。     

PEDOT:PSS薄膜性能优化的研究进展EI北大核心CSCD

作为一种电极材料或电极修饰材料,PEDOT：PSS薄膜常用于有机光电器件领域的应用研究。然而,较低的电导率（≤0．8S／cm）与酸性（pH=1.5～2．5）已成为限制PEODT：PSS薄膜在上述领域进一步应用的瓶颈,因此,PEDOT：PSS薄膜性能优化正在成为一个新的研究热点。文中综述了近年来PEDOT：PSS薄膜性能优化研究的新进展,着重论述了有机物掺杂、无机物掺杂、热处理、紫外／臭氧处理、氧等离子体处理以及外加电场等多种方式对PEDOT：PSS薄膜电／光性能的优化效果及相关机理研究。同时,文章对PEDOT：PSS薄膜性能优化研究工作中存在的焦点问题亦进行了客观分析与评价,并探讨了未来研究重点。     

染料敏化太阳能电池中PEDOT/PSS-CuI复合电解质的研究

以实验室自制的无机P型半导体CuI纳米粉体、导电聚合物PEDOT/PSS及乙腈为原料,制备了PEDOT/PSS-CuI复合电解质及纯CuI固体电解质进行对比。通过X射线衍射(XRD)对CuI粉体的晶形进行了分析,用四探针电阻仪测定了电解质薄膜的电阻率,测试了染料敏化太阳能电池的性能。结果表明:当CuI在PEDOT/PSS中添加量为20%时,PEDOT/PSS-CuI复合电解质组装电池的性能最好。且PEDOT/PSS-CuI复合电解质的性能稳定性要优于纯CuI固体电解质。     

静电纺丝制备Te纳米线/PEDOT:PSS热电薄膜及性能研究

近年来,用于健康、环境监测的可穿戴传感器和电子设备发展迅速,由此对可持续能源收集与供应技术提出了新的要求。有机柔性热电材料和装置能够将热量直接转换成电能,且凭借其固有的柔韧性、低毒性和简单易得等优点,受到越来越多的关注。静电纺丝技术是制备纳米纤维膜的常用方法,具有简单、通用、易于控制等优点,在柔性电子器件领域具有广阔的应用前景。本研究采用静电纺丝结合原位合成的方法制备了碲(Te)纳米线/PEDOT∶PSS热电纳米纤维薄膜,当碲源浓度为5%时(质量分数),Te纳米线长度最长,纤维薄膜的热电性能最佳。其电导率为1.62 S·cm~(-1),塞贝克系数为22.43μV·K~(-1),热导率仅为～0.08 W·m~(-1)·K~(-1),热电优值(ZT值)达0.112×10~(-3)。基于此纤维薄膜成功制备了柔性热电器件,当薄膜条数为4时,在温差ΔT=45 K时,其输出电压为3.54 mV。     

Water‐Enabled Healing of Conducting Polymer Films

The conducting polymer polyethylenedioxythiophene doped with polystyrene sulfonate (PEDOT:PSS) has become one of the most successful organic conductive materials due to its high air stability, high electrical conductivity, and biocompatibility. In recent years, a great deal of attention has been paid to its fundamental physicochemical properties, but its healability has not been explored in depth. This communication reports the first observation of mechanical and electrical healability of PEDOT:PSS thin films. Upon reaching a certain thickness (about 1 µm), PEDOT:PSS thin films damaged with a sharp blade can be electrically healed by simply wetting the damaged area with water. The process is rapid, with a response time on the order of 150 ms. Significantly, after being wetted the films are transformed into autonomic self‐healing materials without the need of external stimulation. This work reveals a new property of PEDOT:PSS and enables its immediate use in flexible and biocompatible electronics, such as electronic skin and bioimplanted electronics, placing conducting polymers on the front line for healing applications in electronics.     

Overcoming Moisture-Induced Degradation in Organic Solar Cells

Unencapsulated organic solar cells are prone to severe performance losses in the presence of moisture. Accelerated damp heat (85 °C/85% RH) studies are presented and it is shown that the hygroscopic hole-transporting PEDOT:PSS layer is the origin of device failure in the case of prototypical inverted solar cells. Complementary measurements unveil that under these conditions a decreased PEDOT:PSS work function along with areas of reduced electrical contact between active layer and hole-transport layer are the main factors for device degradation rather than a chemical reaction of water with the active layer. Replacements for PEDOT:PSS are explored and it is found that tungsten oxide (WO₃) or phosphomolybdic acid (PMA)—materials that can be processed from benign solvents at room temperature—yields comparable performance as PEDOT:PSS and enhances the resilience of solar cells under damp heat. The stability trend follows the order PEDOT:PSS << WO₃ < PMA, with PEDOT:PSS-based devices failing after few minutes, while PMA-based devices remain nearly pristine over several hours. PMA is thus proposed as a robust, solution-processable hole extraction layer that can act as a one to one replacement of PEDOT:PSS to achieve organic solar cells with significantly improved longevity.     

Promising thermoelectric properties of commercial PEDOT:PSS materials and their bi2Te3 powder composites

Newly commercialized PEDOT:PSS products CLEVIOS PH1000 and FE-T, among the most conducting of polymers, show unexpectedly higher Seebeck coefficients than older CLEVIOS P products that were studied by other groups in the past, leading to promising thermoelectric (TE) power factors around 47 μW/m K(2) and 30 μW/m K(2) respectively. By incorporating both n and p type Bi(2)Te(3) ball milled powders into these PEDOT:PSS products, power factor enhancements for both p and n polymer composite materials are achieved. The contact resistance between Bi(2)Te(3) and PEDOT is identified as the limiting factor for further TE property improvement. These composites can be used for all-solution-processed TE devices on flexible substrates as a new fabrication option.     

Improved thermoelectric performance of PEDOT:PSS films prepared by polar-solvent vapor annealing method

To improve thermoelectric performance, polar-solvent vapor annealing (PSVA) method was introduced into the preparation of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films. The solvent vapors included dimethyl sulfoxide, ethylene glycol, N,N-dimethylformamide, N-methyl-2-pyrrolidone, and deionized water (H₂O). The PSVA-treated PEDOT:PSS films exhibited significantly enhanced electrical conductivity and the maximum value was up to 496 S cm^?1. Especially, utilizing the PSVA method, H₂O could also remarkably enhance the electrical conductivity of pristine PEDOT:PSS film from 0.2 to 57 S cm^?1. There was no distinct change for the Seebeck coefficient of PSVA-treated films with the significantly enhanced electrical conductivity, thereby a maximum power factor of 9.47 μW m^?1 K^?2 at room temperature was obtained. The effects of PSVA method on thermoelectric performance of PEDOT:PSS films were also investigated systematically by analyzing the changes in morphology, carrier mobility and carrier concentration. The results confirmed that PSVA-treated PEDOT:PSS films could obtain smoother morphologies and realize the simultaneous increase of carrier mobility and carrier concentration, which results in the improvement of the thermoelectric performance.     

Organic against inorganic electrodes grown onto polymer substrates for flexible organic electronics applications

One of the most challenging topics in the area of organic electronic devices is the growth of transparent electrodes onto flexible polymeric substrates that will be characterized by enhanced conductivity in combination with high optical transparency. An essential aspect for these materials is their synthesis and/or microstructure which define the transparency, the stability and the interfacial chemistry which in turn determine the performance and stability of the organic electronic devices, such as organic light emitting diodes, organic photovoltaics, etc.In this work, we will discuss the latest advances in the growth of organic (e.g. PEDOT:PSS) and inorganic (e.g. zinc oxide-ZnO, indium tin oxide-ITO) conductive materials and their deposition onto flexible polymeric substrates. We will compare the optical, structural, nano-mechanical and nano-topographical properties of the inorganic and organic materials and we investigate the effect of their structure on their properties and functionality. In the case of the organic conductive materials, we will discuss the effects of PEDOT:PSS weight ratios and the various spin speeds on their optical and electrical properties. Furthermore, in the case of ZnO the growth mechanisms, interface phenomena, crystallinity and optical properties of ZnO thin films grown onto polymer and hybrid (inorganic-organic) flexible substrates will be also discussed.     

An Electrochemical Gelation Method for Patterning Conductive PEDOT:PSS Hydrogels

Due to their high water content and macroscopic connectivity, hydrogels made from the conducting polymer PEDOT:PSS are a promising platform from which to fabricate a wide range of porous conductive materials that are increasingly of interest in applications as varied as bioelectronics, regenerative medicine, and energy storage. Despite the promising properties of PEDOT:PSS‐based porous materials, the ability to pattern PEDOT:PSS hydrogels is still required to enable their integration with multifunctional and multichannel electronic devices. In this work, a novel electrochemical gelation (“electrogelation”) method is presented for rapidly patterning PEDOT:PSS hydrogels on any conductive template, including curved and 3D surfaces. High spatial resolution is achieved through use of a sacrificial metal layer to generate the hydrogel pattern, thereby enabling high‐performance conducting hydrogels and aerogels with desirable material properties to be introduced into increasingly complex device architectures.     

An Efficiently Doped PEDOT:PSS Ink Formulation via Metastable Liquid−Liquid Contact for Capillary Flow-Driven,Hierarchically and Highly Conductive Films

With commercial electronics transitioning toward flexible devices, there is a growing demand for high-performance polymers such as poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS). Previous breakthroughs in promoting the conductivity of PEDOT:PSS, which mainly stem from solvent-treatment and transfer-printing strategies, remain as inevitable challenges due to the inefficient, unstable, and biologically incompatible process. Herein, a scalable fabrication of conducting PEDOT:PSS inks is reported via a metastable liquid−liquid contact (MLLC) method, realizing phase separation and removal of excess PSS simultaneously. MLLC-doped inks are further used to prepare ring-like films through a compromise between the coffee-ring effect and the Marangoni vortex during evaporation of droplets. The specific control over deposition conditions allows for tunable ring-like morphologies and preferentially interconnected networks of PEDOT:PSS nanofibrils, resulting in a high electrical conductivity of 6,616 S cm⁻¹ and excellent optical transparency of the film. The combination of excellent electrical properties and the special morphology enables it to serve as electrodes for touch sensors with gradient pressure sensitivity. These findings not only provide new insight into developing a simple and efficient doping method for commercial PEDOT:PSS ink, but also offer a promising self-assembled deposition pattern of organic semiconductor films, expanding the applications in flexible electronics, bioelectronics as well as photovoltaic devices.     

MWCNT/PEDOT复合材料的微观结构和热电性能

热电转换技术能将大量的废弃热能转换为电能以重新利用,是一种绿色能源转换技术,可以有效提高能源利用效率,缓解煤炭、石油等主要化石类能源过度开采、使用带来的能源危机及环境污染问题,因此受到科研工作者的广泛关注,是近年来的研究热点。基于此,本文以电子型导电高聚物中机能较优的聚(3, 4-乙烯二氧噻吩)(PEDOT)作为研究主体,通过化学原位氧化聚合将多壁碳纳米管(MWCNT)复合到载体中得到MWCNT/PEDOT复合材料。利用XRD、拉曼、TEM及正电子湮没寿命(PAL)等方法对MWCNT/PEDOT复合材料的形貌和微观结构进行了系统研究,研究表明:当MWCNT含量高于24.9wt%时,复合材料中出现MWCNT团聚现象,其分散性变差。同时,MWCNT/PEDOT复合材料的热电性能测试结果显示,未掺杂PEDOT的电导率仅为7.5 S·m?1,而MWCNT含量为30.1wt%时,该复合材料的电导率高达566.59 S·m?1,提高近76倍。同时,30.1wt%MWCNT/PEDOT的功率因子(814.3×10?4 μW·(m·K2)?1)相对于未掺杂PEDOT(14.5×10?4 μW·(m·K2)?1)提高约56倍,这主要是由于PEDOT分子链与MWCNT掺杂物间π-π相互作用及MWCNT的高导电性。随着MWCNT含量的增加,PAL测试结果中第一寿命成分τ₁(即正电子在材料中湮没的第一寿命成分)的下降证实了该复合材料中MWCNT与PEDOT间界面变小或者界面间相互作用减弱,导致其热导率相对于未掺杂PEDOT有一定的上升,但远远低于功率因子的升高。最终,该MWCNT/PEDOT复合材料的热电优值(即热电材料Z_T值)由0.015×10?4升至0.45×10?4,增加了约30倍。结果表明:掺杂的高电导率MWCNT能够极大地提高PEDOT类电子型导电聚合物的热电性能。