含有π桥的非富勒烯小分子受体的研究

非富勒烯受体材料的设计合成受到广泛的关注,通过化学结构裁剪,器件工艺不断优化,其与聚合物给体材料所组成的有机光伏电池的效率已超过富勒烯衍生物,近两年报道以非富勒烯类小分子作为受体材料的器件效率不断攀升,已经超过17%。通过对近几年基于非富勒烯受体的高效有机光伏电池进行综述,了解近几年非富勒烯受体材料的研究进展,总结其不同设计策略及意义。     

基于苯并噻二唑稠环核的非富勒烯受体研究进展

大量关于有机光伏电池受体材料研究工作显示,富勒烯受体材料及其衍生物是过去十几年的研究主流,但是其可见光吸收弱,成本较高,形貌稳定性差等缺点明显,而且基于富勒烯受体的有机太阳能电池效率也已接近理论极限,难以有所突破。因此,非富勒烯受体材料的设计合成受到广泛的关注,通过化学结构裁剪,器件工艺不断优化,其与聚合物给体材料所组成的有机光伏电池的效率已超过富勒烯衍生物,近两年报道以非富勒烯类小分子作为受体材料的器件效率不断攀升,已经超过17%。通过对近几年优秀的非富勒烯受体进行综述,了解近几年非富勒烯受体材料的研究进展,总结其不同设计策略及意义。     

两种富勒烯二加成受体材料的合成

合成了两种聚合物光伏电池的电子受体材料,并进行了结构和性能表征。提高了其LUMO能级,用于聚合物光伏电池有望提升器件的开路电压。     

新型含DPP结构单元的有机小分子化合物的合成

有机小分子太阳能电池材料因价格低廉,材料多样且易合成等优点而备受关注。近年,由给电子结构单元和吸电子结构单元连接的有机小分子太阳能电池材料由于能促进分子内电荷分离,降低分子能级,引起了人们广泛的关注。本文选取吡咯并吡咯二酮(DPP)为中心吸电子单元,甲氧基萘为给电子单元利用C-C直接偶联的方法成功了合成了一种新型D-A-D型有机小分子太阳能电池光伏材料。并利用紫外吸收光谱研究了其光物理性能。结果表明该化合物的紫外吸收光谱的最大吸收波长为800 nm。     

苝酰亚胺小分子在有机太阳能电池中的应用

苝酰亚胺类材料是研究最早并且最常见的非富勒烯电子受体材料,具有良好的光、热、化学稳定性、较高的摩尔吸光系数、较宽的太阳光谱响应范围、良好的电子传输能力、较高的电子亲和势和较强的接受电子能力等优点,是目前最好的n-型有机半导体材料之一。本文以苝酰亚胺和并噻吩为原料,合成一种大平面的苝酰亚胺小分子(PDI-TT-PDI),并以PCE10为给体,以PDI-TT-PDI为受体,考查了不同给受体比例、添加剂含量、不同退火温度对于器件效率的影响。     

氟原子对苯并二噻吩类共轭聚合物光伏性能的影响

设计合成了两种D-A型共轭聚合物给体材料PBDT-BT,PBDT-FBT,研究了引入氟原子后,双直链噻吩修饰的苯并二噻吩共轭聚合物的热力学,光学,电学性质与光伏性能的变化。以聚合物/PC71BM作为活性层材料,研究了不同比例的给体受体对有机太阳能电池光伏性能的影响。两种聚合物热力学分解温度均超过了400℃,同时表现出不错的吸光能力。较低的HOMO能级使得PBDT-BT与PBDT-FBT的开路电压均超过了0.85 e V,通过器件结构ITO/PEDOT:PSS/Active Layer/Ca/Al,优化得到的光伏性能分别为2.42%与3.55%。     

新型多环thienoacene基共轭聚合物太阳能电池研究进展

近年来,用于体异质结有机光伏器件的聚合物给体材料的发展受到了广泛关注,多环thienoacene与一些性能优良的电子受体单元构建的电子给体-受体型窄带隙共轭聚合物,具有良好的π-π堆积性能和高电荷迁移率,是当前高效聚合物太阳能电池的研究热点。本文概述了几类thienoacene基共轭聚合物作为电子给体与电子受体PCBM下的光伏器件的研究进展及取得的成就,同时对其存在问题与拟解决途径做了简要阐述。     

双极性材料在有机太阳能电池领域的应用

双极性材料以其低能隙、宽吸收、高电子传导率和较高稳定性的优势成为增强有机太阳能电池性能的优良材料。研究显示,双极性材料不但能够作为有机光伏器件中的给体材料和受体材料,还能作为辅助添加剂来增加电池的能量转化效率。     

窄带隙共轭聚合物/富勒烯衍生物光探测器件的研究

基于高灵敏度、宽光谱响应的窄带隙共轭聚合物光探测器件的研究取得了突破性进展,受到了学术界和产业界的高度重视,成为了当前光探测器件研究的热点课题之一.本文概述了窄带隙共轭聚合物作为电子给体与电子受体PC61BM下光伏器件的研究进展及存在的问题.提出了带隙更窄、光谱响应更宽的共轭聚合物的合成与器件的优化研究将具有更大的发展...     

基于Y6小分子性能优化策略综述

随着给体和受体材料的不断发展，有机太阳能电池的光电转换效率逐步提升。尤其是稠环受体小分子Y6的合成，使单节有机太阳能电池的效率独创新高，突破了15%。目前Y6已经应用于有机太阳能电池，并都取得了可观的成绩。进一步提高有机太阳能电池的光电转换效率，使其商业化是我们一直追求的目标。本综述主要总结了从不同方面优化Y6基受体小分子，提高OSC的光电转化效率。包括调整Y6结构，选择新的供体以及器件工程。     

Gel permeation chromatography: Evaluation of porous glass-column packing materials for low molecular weight solutes

Currently available small pore-size porous glass packing materials have been characterized as substrates for gel permeation-chromatographic separations. The elution volumes of narrow molecular weight-distribution polystyrene standards and hydrocarbon solutes have been determined using tetrahydrofuran as solvent. The results show that none has a sufficiently small pore diameter to enable low molecular weight oligomers to be separated. New smaller pore-diameter packing materials are required to enable these rigid materials to be used for separations of oligomer mixtures by GPC.     

Higher‐molecular‐weight hyperbranched polyethylenes containing crosslinking structures as lubricant viscosity‐index improvers

As a new grade of polyethylene materials with unique chain architectures, hyperbranched polyethylenes synthesized by chain walking ethylene polymerization have great potential for industrial application as novel viscosity index (VI) improver in lubricant formulation. Although high‐molecular‐weight hyperbranched polyethylenes (weight‐average molecular weight of about 10⁵ g/mol) possess high shear stability, their viscosity thickening properties are compromised due to their compact chain architectures. In this work, we aim at improving their viscosity thickening property by increasing polymer molecular weight. A range of hyperbranched polymers of various enhanced molecular weights were synthesized by chain walking ethylene polymerization in the presence of small amounts of 1,4‐butanediol diacrylate as a difunctional crosslinker. The molecular weight dependences of viscosity thickening power and shear stability of these polymers containing crosslinking structures were evaluated. It is found that, with the increase of molecular weight via crosslinking, these polymers showed consistently enhanced viscosity thickening power, but with the reduced shear stability. However, their shear stability was still significantly better compared to linear polymers. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

小分子离子自组装制备功能超分子材料

离子自组装是合成功能超分子材料的有力途径,而带相反电荷的小分子离子之间的离子自组装由于具有良好的结构可设计性和功能可调节性,是离子自组装制备功能超分子材料领域的研究热点。本文首先对离子自组装的特点进行了简单的介绍,然后分3类对小分子离子自组装制备功能超分子材料领域进行了综述,主要包括染料与表面活性剂自组装制备功能材料,平面刚性离子自组装制备功能材料以及多金属酸盐离子自组装制备功能材料。目前,小分子离子自组装在组装单元的选择以及材料功能扩展角度已取得了长足的进步,但如何实现利用小分子离子自组装从微观结构到宏观材料的跨度,制备出能在实际生产中应用的功能超分子材料,还有待进一步发展。     

Mechanical modeling and simulation of aerogels: A review

Aerogels are solids with exceptional characteristics, such as ultra-low density, high surface area, high porosity, high adsorption and low-thermal conductivity. Due to these characteristics, aerogels are emerging to be a popular material among the scientific community, since their discovery in 1931. However, their applicability has remained questionable due to the poor mechanical characteristics, such as brittleness and low tensile strength. In the last three decades, due to the rapid development in the computational resources and numerical methods, a deeper understanding of physical behavior and properties of these materials have been extensively investigated. In this work, an effort is made to critically analyze and categorize the computational models and simulation results available for silica, carbon, carbon nanotubes, graphene, and cellulose aerogels. This work focused on a better understanding of how these materials were computationally modeled and simulated over the time-period and at different length-scales, wherein primary approaches, such as molecular dynamics (MD), coarse-grained, micromechanical multiscale and continuum mechanics modeling, were discussed. It also strives to give an insight into the areas where further computational studies are required, which could lead to numerous other application fields. The systematic review provides a mechanistic basis for reliable applications of aerogels.     

Application of living free radical polymerization for nucleic acid delivery

Therapeutic gene delivery can alter protein function either through the replacement of nonfunctional genes to restore cellular health or through RNA interference (RNAi) to mask mutated and harmful genes. Researchers have investigated a range of nucleic acid-based therapeutics as potential treatments for hereditary, acquired, and infectious diseases. Candidate drugs include plasmids that induce gene expression and small, interfering RNAs (siRNAs) that silence target genes. Because of their self-assembly with nucleic acids into virus-sized nanoparticles and high transfection efficiency in vitro, cationic polymers have been extensively studied for nucleic acid delivery applications, but toxicity and particle stability have limited the clinical applications of these systems. The advent of living free radical polymerization has improved the quality, control, and reproducibility of these synthesized materials. This process yields well-defined, narrowly disperse materials with designed architectures and molecular weights. As a result, researchers can study the effects of polymer architecture and molecular weight on transfection efficiency and cytotoxicity, which will improve the design of next-generation vectors. In this Account, we review findings from structure-function studies that have elucidated key design motifs necessary for the development of effective nucleic acid vectors. Researchers have used robust methods such as atom transfer radical polymerization (ATRP), reverse addition-fragmentation chain transfer polymerization (RAFT), and ring-opening metastasis polymerization (ROMP) to engineer materials that enhance extracellular stability and cellular specificity and decrease toxicity. In addition, we discuss polymers that are biodegradable, form supramolecular structures, target specific cells, or facilitate endosomal release. Finally, we describe promising materials with a range of in vivo applications from pulmonary gene delivery to DNA vaccines.     

On agglomeration phenomena in ball mills: application to the synthesis of composite materials

Composites of poly(vinyl acetate) filled with calcium carbonate (CaCO₃) have been synthesized in a ball mill. The different steps in fragmentation and agglomeration phenomena have been identified. The materials have first been ground separately to characterize their behaviour in the mill. Then, they were ground together. It has been shown that small CaCO₃ fragments cover PVA particles, limiting for a first time the agglomeration of these and permitting their size reduction. Then, when PVA fragments are small enough, a competition between size reduction and agglomeration occurs, which favours the dispersion of CaCO₃ in the matrix. It has also been observed that the presence of the filler does not modify significantly the molecular mobility of PVA.     

High quality mesoporous materials prepared by supercritical fluid extraction: effect of curing treatment on their structural stability

Mesoporous molecular sieves like SBA-1, SBA-3, MCM-41 and MCM-48 are generally synthesized by using a quaternary ammonium surfactant as a structure-directing agent to form a porous silica framework. The used templating agent is conventionally removed for producing mesopores by calcination at high temperature. In this study, supercritical fluid extraction (SFE) has been employed to remove organic templates from these materials. We found that more than 80% of the templating agent can be successfully removed by using this technique. Among these materials, SBA-3 was observed to experience the collapse of mesoporous structures upon the SFE process. Thus, we have proposed pre-SFE thermal aging as a curing treatment method and found that it has significantly improved the mesoporous structural stability of SBA-3. In the meantime, this curing method has lead to these SFE-processed materials with better ordered mesoporous structures, such as SBA-3 having specific surface area as large as 1670 m²/g.     

Use of MALDI-ToF MS to elucidate the structure of oligomeric impurities formed during ‘click’ cyclization of polystyrene

Polymers with a cyclic topology exhibit a range of unique and potentially useful physical properties, including reduced rates of degradation and increased rates of diffusion in bulk relative to linear analogs. However, the synthesis of high purity cyclic polymers and verification of their structural purity remain challenging. The copper-catalyzed azide–alkyne “click” cyclization route toward cyclic polymers has been widely used, due to its synthetic ease and its compatibility with diverse polymer backbones. Yet unoptimized click cyclization conditions have been observed to generate oligomeric byproducts. In order to optimize these cyclization conditions, and to better understand the structure of the higher molecular weight oligomers, these impurities have been isolated and characterized. Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI–ToF) MS is a particularly valuable characterization tool and was used to determine that the high molecular weight impurities are predominantly cyclic oligomers. It should also be noted that the rapid analysis and small analyte requirements of this MS technique make it particularly attractive as a general tool for elucidating polymer architecture.     

Polyimides from diisocyanates,dianhydrides, and their dialkyl esters

High molecular weight polyimide polymers have been prepared by the reaction of dissocyanates and a mixture of dianhydrides and their dialkyl esters in aprotic solvents. No catalyst is necessary, but high polymer formation is affected by the anhydride/ester ratio and temperature. Dianhydrides such as PMDA, BTDA, TMA, and their esters have been used successfully. Mixtures of these materials have also been used. Tough, flexible films can be obtained from these polymers.     

Organic Host Materials for Solution-Processed Phosphorescent Organic Light-Emitting Diodes

As a new technology for flat-panel displays and general lighting sources, solution-processed phosphorescent organic light-emitting diodes (PhOLEDs) unfurl a bright future, due to their merits of high quantum efficiency and easy fabrication. In recent years, great progress has been made in the device performance of solution-processed PhOLEDs, by developing both high-efficiency organometallic phosphors and novel solution-processable organic host materials. This review highlights recently developed organic host materials for triplet guest emitters in solution-processed PhOLEDs. The solution-processable host materials are classified into three types – small molecule, dendrimer, and polymer – according to their molecular architecture and molecular weight. The material design concept and the relationships between the molecular structure, material properties and device performance are the focus of this discussion. A future strategy for the development of high-performance solution-processed host materials is proposed.