聚合物太阳能光伏技术研究进展

聚合物太阳电池因其结构简单、成本低、重量轻和可制成柔性器件等突出优点,近年来受到广泛关注,成为发展绿色可再生能源的重要方向。聚合物太阳电池中的给体和受体光伏材料是决定器件性能的关键,本文综述了共轭聚合物给体和富勒烯受体光伏材料的最新研究进展,并在共轭聚合物给体材料中对聚噻吩衍生物以及窄带隙D-A共聚物进行了重点介绍。同时讨论了薄膜优化和器件稳定性,最后从提高电池效率的几个方面展望了聚合物太阳电池的发展方向。     

基于噻咯的聚合物给体光伏材料

聚合物太阳能电池由于具有结构简单、成本低、重量轻和可制成柔性器件等突出优点,近几年受到了越来越多的关注。但是,与传统的无机硅系太阳能电池相比,较低的能量转换效率一直是制约其发展的瓶颈。近年来大量的研究显示,噻咯结构单元被引入给-受体(D-A)型共轭聚合物光伏材料中,能有效地改善相应聚合物的结晶性能,并调节其能级结构(HOMO/LUMO),从而显著改善聚合物的光伏性能。本文综述了含有噻咯环的低能隙共轭聚合物给体光伏材料的研究进展,重点介绍了含有二噻吩并噻咯单元的窄带隙D-A共轭聚合物的最新研究,并进一步提出了给体材料的研究方向以及有待解决的问题。     

聚合物太阳电池光伏材料

聚合物太阳电池由共轭聚合物给体和可溶性富勒烯衍生物受体的共混膜夹在ITO透光电极和金属电极之间所组成,具有结构简单、成本低、重量轻和可制成柔性器件等突出优点,近年来受到广泛关注。聚合物太阳电池中的给体和受体光伏材料是决定器件性能的关键。本文综述了共轭聚合物给体和富勒烯受体光伏材料的最新研究进展,对共轭聚合物受体材料和给体-受体双缆型共轭聚合物光伏材料的研究进展也进行了简要介绍。在共轭聚合物给体材料中对聚噻吩衍生物以及含有苯并噻二唑的窄带隙D-A共聚物进行了重点介绍。     

聚合物太阳能电池材料的研究进展

有机光伏技术为太阳能的有效利用提供了一条重要途径。有机太阳能电池因制造成本低廉、材料质量轻、加工性能好、易于携带等优势而备受关注。提高有机太阳能电池的光电转换效率是目前乃至未来的研究重点。设计和合成适合的窄带隙的共轭聚合物是提高有机太阳能电池光电转化效率的核心。综述了近年来基于窄带隙的共轭聚合物的太阳能电池材料的设计、制备和器件性能研究进展,探讨了目前存在的亟待解决的关键基础问题和未来发展方向。     

高性能聚合物光伏材料的设计与应用

高性能聚合物光伏材料对于推动聚合物太阳能电池领域的发展具有十分重要的作用.随着研究的深入,聚合物光伏材料从早期的聚噻吩体系逐步发展到具有推拉电子作用的给体-受体(D-A)交替共聚物,其相应的器件光伏效率也从最初的1%左右提升到如今超过11%.近十年来,种类繁多的给受体单元被开发并应用于聚合物材料的构建中,其中基于苯并二噻吩(BDT)单元的聚合物材料因为具有良好的光伏性能,得到了十分广泛的应用.近年来,非富勒烯受体的迅速发展给聚合物太阳能电池的研究注入了新的活力,BDT类聚合物在基于非富勒烯受体的聚合物太阳能电池中也展现出重要的作用,已经获得了超过11%的光电转化效率.本文简要介绍了我们在高性能聚合物光伏材料的设计与应用中的相关工作,主要分为聚噻吩和苯并二噻吩材料的设计与应用、活性层形貌调控以及非富勒烯聚合物太阳能电池的相关研究.     

非富勒烯聚合物太阳电池研究进展

综述了以p-型共轭聚合物为给体、n-型有机半导体为受体的非富勒烯聚合物太阳电池光伏材料最新研究进展,包括n-型共轭聚合物和可溶液加工小分子n-型有机半导体(n-OS)受体光伏材料,以及与之匹配的p-型共轭聚合物给体光伏材料.介绍的n-型共轭聚合物受体光伏材料包括基于苝酰亚胺(BDI)、萘酰亚胺(NDI)以及新型硼氮键连受体单元的D-A共聚物受体光伏材料,目前基于聚合物给体(J51)和聚合物受体(N2200)的全聚合物太阳电池的能量转换效率最高达到8.26%.n-OS小分子受体光伏材料包括基于BDI和NDI单元的有机分子、基于稠环中心给体单元的A-D-A型窄带隙有机小分子受体材料等.给体光伏材料包括基于齐聚噻吩和苯并二噻吩(BDT)给体单元的D-A共聚物,重点介绍与窄带隙A-D-A结构小分子受体吸收互补的、基于噻吩取代BDT单元的中间带隙二维共轭聚合物给体光伏材料.使用中间带隙的p-型共轭聚合物为给体、窄带隙A-D-A结构有机小分子为受体的非富勒烯聚合物太阳电池能量转换效率已经突破12%,展示了光明的前景.最后对非富勒烯聚合物太阳电池将来的发展进行了展望.     

含噻吩窄带隙共轭聚合物类太阳能电池材料的研究进展

含噻吩的窄带隙共轭聚合物类太阳能电池材料因其良好的稳定性和可加工性,已成为新型太阳能电池的研究热点。本论文主要介绍了用于太阳能电池的窄带隙共轭聚合物研究进展,按其结构特征分为烷基/烷氧基取代聚噻吩、含苯基聚噻吩、基于噻吩并吡嗪的共聚物、基于噻吩并噻唑的共聚物、基于噻吩并吩噻嗪的共聚物、基于烷基芴的共聚物以及其它种类的窄带隙的共轭聚合物,并对它们的结构特点、光学带隙、合成方法进行了归纳与总结。本文最后简要介绍了该研究领域目前所面临的一些问题,同时讨论了该类材料在此领域今后的发展趋势。     

聚合物太阳能电池给体材料研究进展

随着能源和环境问题日益严重,人们日益关注于太阳能的开发和应用。同时,无机太阳能电池因其自身原因而受到限制,聚合物太阳能电池受到更多的关注。在聚合物基的太阳能电池中,给体材料制约着电池效率的提高,其中材料的带隙和能级是影响其性能的主要因素。而通过研究和选取具有合适带隙和能级的给体材料可以有效地调节电池器件的效率。本文介绍了太阳能电池给体材料的设计原则与主要影响因素,并叙述了近年来该领域内的研究进展和以及发展前景。     

1,4-二酮吡咯并吡咯在聚合物太阳能电池的应用

1,4-二酮吡咯并吡咯(DPP)由于具有优异的共平面性和强烈的拉电子能力,从而被引入D-A型窄带隙共轭聚合物中调控聚合物材料的能隙和能级结构,拓宽在可见光区域的响应范围。近年来,DPP类聚合物太阳能电池材料的研究受到广泛关注,目前基于DPP的聚合物太阳能电池效率高已达9.64%。本文探讨了以DPP作为受体单元而噻吩衍生物、芴、咔唑和苯并二噻吩等作为给体单元制成的D-A型窄带隙共轭聚合物太阳能电池的研究进展,并探讨了聚合物材料结构与太阳能电池性能之间的内在构效关系。     

含有呋喃衍生物的窄带隙共轭聚合物的合成及光伏性能研究

通过Stille法将呋喃衍生物苯并二呋喃(BDF)引入共轭主链,合成了苯并二呋喃-呋喃-苯并恶二唑共聚物(Polymer 1,简称P1).以紫外吸收光谱分析了聚合物溶液及其膜的基本光谱特征,通过理论计算进行了分子模拟,并用电化学循环伏安法测定了其基本的电化学性质.采用此材料为给体,PC71BM为受体制备了本体异质结型的有机太阳能电池器件,同时研究了不同给/受体重量比的情况下以及1,8-二碘辛烷作为添加剂的情况下的光伏器件性能.结果表明,P1聚合物在可见光区具有较大吸收.由P1所制得的光伏器件,在AM1.5的模拟太阳光照射条件下最高的转化效率为2.96%,表明BDF基团的引入可实现窄带隙的光电聚合物.     

Modification of Particle Filled Polymers with High Energy Electrons Under In-Stationary Conditions of Melt Mixing

Summary: Polymer modification with high energy electrons is well-established in polymer industry and used for degradation, cross-linking, grafting, curing, and polymerization. These applications use local and temporal precise input of energy in order to generate excited atoms or molecules and ions for subsequent molecule changes via radical induced chemical reactions. In the present study, high energy electrons have been used to modify polyolefine (polyethylene and polypropylene) systems in presence of a grafting agent under stationary and in-stationary conditions. Polymer modification with high energy electrons under stationary conditions characterizes a process where required absorbed dose is applied to polymers in solid state and at room temperature. Polymer modification with high energy electrons under in-stationary conditions is a novel process where required absorbed dose is applied in molten state during melt mixing process. In this novel process, the penetration depth of electrons is limited to a part of mixing volume. The total mixing volume is modified due to the change of polymer mass within the penetration depth of electrons during mixing process. A 1.5 MeV electron accelerator has been directly coupled to a banbury mixing chamber in order to study this novel process. In comparison to the stationary process, the main differences are working at higher temperature, absence of any crystallinity, intensive macromolecular mobility as well as intensive mixing during dose application. The influence of both processes on mechanical properties and flame resistance of polymer composites is discussed.     

Energy requirements for the disintegration of cellulose fibers into cellulose nanofibers

Cellulose nanofibers have a bright future ahead as components of nano-engineered materials, as they are an abundant, renewable and sustainable resource with outstanding mechanical properties. However, before considering real-world applications, an efficient and energetically friendly production process needs to be developed that overcomes the extensive energy consumption of shear-based existing processes. This paper analyses how the charge content influences the mechanical energy that is needed to disintegrate a cellulose fiber. The introduction of charge groups (carboxylate) is achieved through periodate oxidation followed by chlorite oxidation reactions, carried out to different extents. Modified samples are then subjected to different levels of controlled mechanical energy and the yields of three different fractions, separated by size, are obtained. The process produces highly functionalized cellulose nanofibers based almost exclusively on chemical reactions, thus avoiding the use of intensive mechanical energy in the process and consequently reducing drastically the energy consumption.     

Organogels as scaffolds for excitation energy transfer and light harvesting

The elegance and efficiency by which Nature harvests solar energy has been a source of inspiration for chemists to mimic such process with synthetic molecular and supramolecular systems. The insights gained over the years from these studies have contributed immensely to the development of advanced materials useful for organic based electronic and photonic devices. Energy transfer, being a key process in many of these devices, has been extensively studied in recent years. A major requirement for efficient energy transfer process is the proper arrangement of donors and acceptors in a few nanometers in length scale. A practical approach to this is the controlled self-assembly and gelation of chromophore based molecular systems. The present tutorial review describes the recent developments in the design of chromophore based organogels and their use as supramolecular scaffolds for excitation energy transfer studies.     

Membrane separations in ethanol recovery: an analysis of two applications of hyperfiltration

With further development, membrane separations have the potential to contribute to process improvements, especially for energy conservation, in ethanol fuel production. Two applications of hyperfiltration (reverse osmosis) in the recovery and purification of ethanol from fermentation beer are defined and analyzed for energy requirements and economics. These analyses are performed for a complete plant, including a recovery subprocess with and without the use of hyperfiltration. The hyperfiltration processes are designed using existing data for available membranes and hypothetical data for advanced membranes. The overall purpose of these analyses is to identify process modifications and membrane-related research that can contribute to decreasing the energy requirements of ethanol fuel production.

In one application, hyperfiltration is used in a lignocellulose-to-ethanol plant to preconcentrate low-proof (2 wt% beer prior to further purification by fractional and azeotropic distillation. This application requires ethanol-rejecting membranes, which are developed. When lignocellulose is used as a feedstock for ethanol production, a low-proof beer is usually produced. The energy requirements of ethanol recovery from low-proof beer by conventional distillation exceed the energy content of ethanol and frequently preclude the feasibility of producing ethanol from lignocellulose. The use of hyperfiltration to preconcentrate ethanol can significantly reduce the energy requirements of ethanol recovery from low-proof beer. The analyses are based upon process designs using existing and hypothetical membranes. This application is found to conserve 19 to 20 GJ/m³ (67,000 to 72,000 Btu/gal) of anhydrous ethanol as compared to only fractional and azeotropic distillation and to be economically competitive (with a 2 to 4% lower price). The analysis indicates that this application of hyperfiltration is promising and that future research should be devoted to increasing flux (while maintaining or improving ethanol rejection) and to assessing and improving membrane life.

In the other application, hyperfiltration is used to dehydrate high-proof (93 to 95 wt%) ethanol in a corn-to-ethanol plant. Ethanol dehydration is an energy-intensive separation, generally requiring 2.0 to 2.8 GJ/m³ (7,000 to 10,000 Btu/gal) of anhydrous ethanol. This application was designed based upon hypothetical, water-rejecting hyperfiltration membranes, which are not pres ently developed. Although the hyperfiltration process is found to conserve 0.8 GJ/m³ (2,900 Btu/gal) of anhydrous ethanol, it is not found to have an economic advantage over a conventional ethanol purification process. Therefore, this application is not found to be promising and little incentive exists for performing research aimed at development of a water-rejecting membrane for the dehydration of ethanol by hyperfiltration.

Finally, thoughts regarding the use of membrane separations in the chemical/fuel industry are presented.     

Microbial reduction of SO2 as a means of byproduct recovery from regenerable,dry scrubbing processes for flue gas desulfurization

A project is under way at the University of Tulsa to investigate the reduction of SO₂ to H₂S by sulfate reducing bacteria (SRB) in co-culture with mixed fermentative heterotrophs. We have previously demonstrated that SO₂ is completely reduced to H₂S (contact times of 1–2 s) in cultures in which no redox poising agents were required and glucose served as the ultimate source of carbon energy. We have proposed that such a microbial process could be coupled with a Claus reactor to recover elemental sulfur as a byproduct of regenerable, dry scrubbing processes for flue gas desulfurization. The development of this process concept has continued with a study of the use of molasses as a source of carbon and reduced nitrogen, identification of important non-SRB heterotrophs in process cultures, and the identification of the end products of carbohydrate fermentation that serve as carbon and energy sources for the SRB and identification of the end products of SRB metabolism.     

Determination of the interconversion energy barrier of enantiomers by separation methods

Separation methods have become versatile tools for the determination of kinetic activation parameters and energy barriers to interconversion of isomers and enantiomers in the last 20 years. New computer-aided evaluation systems allow the on-line determination of these data after separating minute amount of pure compounds or mixture of isomers or enantiomers, respectively. Both dynamic interconversion during the separation process as well as static stopped-flow techniques have been applied to determine the kinetic activation parameters and interconversion energy barriers by separation methods. The use of (1) combinations of batchwise kinetic studies with enantioselective separations, (2) a continuous flow model, (3) a comparison of real chromatograms with simulated ones, (4) stopped-flow techniques, (5) stochastic methods, (6) approximation functions and (7) deconvolution methods, for the determination of interconversion energy barriers by separation methods is summarized in detail.     

Interface identification by non-local autoionization transitions

We use an autoionization process that involves ultrafast energy transfer to neighbouring sites to characterize the formation of NeAr van der Waals bonds in clusters formed by a coexpansion of both gases. This autoionization process, the so-called interatomic or intermolecular coulombic decay (ICD), is ubiquitous in weakly bonded systems. The energy of the electron being emitted in the ICD process is shown to be characteristic of the two neighbouring entities and is therefore suggested as a new means for structural investigation, such as interface identification, of weakly bonded complexes.     

Using Kinetic Modeling and Experimental Data to Evaluate Mechanisms in PET-RAFT

Reversible deactivation radical polymerization (RDRP) techniques have become important tools for polymer chemists because they control the structure and are tolerant to functionality. Photoinduced polymerizations have seen a growing interest due to their mild conditions, as well as spatial and temporal control over the polymerization. Among these techniques, photoinduced electron/energy transfer reversible addition–fragmentation chain transfer polymerization (PET-RAFT) is one of the most widely investigated. While PET-RAFT is seen as an increasingly useful tool, there is still much to understand about the mechanism of this process. In particular, there are ongoing questions regarding the kinetic contribution of electron versus energy transfer. In order to better understand the mechanism, this work aims to use kinetic modeling along with experimental data to help determine the likelihood of the proposed mechanisms for the PET-RAFT process using the trithiocarbonate-mediated polymerization of methyl acrylate with fac-tris[2-phenylpyridinato-C²,N]iridium(III) as a photocatalyst. Simulation data show that electron transfer without a corresponding reduction pathway cannot explain the experimental kinetics, while energy transfer offers a good fit to experimental data. © 2019 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 139–144     

Improved sulfuric acid decrystallization of wheat straw to obtain high yield carbohydrates

Wheat straw is an abundant residue of agriculture which is increasingly considered as a feedstock for the production of fuels, energy and chemicals. The concentrated acid hydrolysis of wheat straw has been investigated in this work. Hemicellulose and cellulose have been efficiently converted into monomers of pentoses and glucose in high yields by a one-pot decrystallization-hydrolysis procedure. This process differs from usual concentrated acid biomass fractionation methodologies as a low quantity of acid is used and the supplementary use of a costly acid is not necessary to yield efficiently carbohydrates. The influence of the acid native concentration, and of the time of the decrystallization step have been studied so as to optimise yields of carbohydrates using a minimum of sulfuric acid so as to preserve a potential market value of the process. One can also imagine that this procedure will not impact dramatically the subsequent purification costs. In view of the growing importance of renewable resource-based molecules in the chemical industry, and the necessity to produce fermentable substrate for biofuels, this approach may open a new avenue for the use of wheat straw as raw material for various applications.     

A Re‐Examination of the Concept of Hildebrand Solubility Parameter for Polymers

With the use of molecular modeling, we have demonstrated that solubility parameters obtained from current experimental methods correspond to a hypothetical vaporization process of which the conformational change of macromolecules in the vapor state is ignored. Since the energy associated with such a process is relatively large, its impact on the resultant δ cannot be neglected. This is especially important for polymers that shrink considerably in the vapor state.