中科院化学所在非富勒烯型聚合物太阳能电池研究中取得系列进展

正近年来,聚合物太阳能电池由于其重量轻、价格低廉、可通过印刷的方式制备大面积柔性器件等优势,得到了学术界和工业界的广泛关注,是重要的前沿研究领域。聚合物太阳能电池的活性层通常由基于聚合物/有机小分子的电子给体和电子受体共混而成。作为电子受体材料,以PCBM为代表的富勒烯类n-型有机半导体已经被广泛应用于聚合物太阳能电池中,基于聚合     

富勒烯材料在钙钛矿太阳能电池中的应用

有机无机杂化钙钛矿太阳能电池自2009年出现以来，经过短短十余年的发展，光电转化效率已提升到24%以上，引起了广泛的关注。富勒烯材料具有较高电子迁移率、可调控的能级以及可低温成膜等特性，在钙钛矿太阳能电池中可以用于电子传输层、钙钛矿层添加剂、界面修饰层，甚至还能够在空穴传输层中发挥作用。这些应用不仅提高了电池的光电转化效率和稳定性，还能有效降低电池的磁滞效应。本综述就富勒烯材料在钙钛矿太阳能电池各组成部分的应用进行了详细的介绍，并总结了通过修饰富勒烯分子结构提高电池性能的基本规律，这些结果对推动富勒烯材料在钙钛矿太阳能电池领域的应用有重要意义。     

基于稠环核的非富勒烯受体材料的光伏研究进展

有机太阳能电池因其生产成本低廉、质轻、易于大面积制备等明显优势,近年来已成为发展最为迅速的研究领域之一。其中,活性层材料是有机太阳能电池研究的基础和关键。在过去几十年当中,富勒烯及其衍生物一直是有机太阳能电池的重要研究方向,但其众多缺点限制了光伏性能的进一步提升。非富勒烯受体材料因分子结构、能级可调,近年,结构新颖、性能优异的非富勒烯受体材料相继被开发出来,掀起了有机太阳能电池领域的又一个研究热潮。通过对近几年基于引达省并二噻吩(ITIC类)受体和基于苯并噻二唑(Y6类)的发展进行综述,并在此基础上,对ITIC类和Y6类有机太阳能电池的研究进行了进一步讨论及展望,以期为未来非富勒烯受体材料的结构设计与优化提供参考思路。     

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。     

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。     

聚合物太阳能电池富勒烯衍生物受体材料的制备及其表征

作为新能源,由于有机太阳能电池具有量轻、易于大面积柔性制备等特点,最近有机聚合物太阳能电池的开发得到了越来越多的关注,其光电转化效率最高值不断被刷新,这也带动了新材料的研发。本论文设计并合成了2个噻吩-富勒烯(C60)二元结构的化合物,用作电池的受体活性材料,进一步可开发成D-A型活性材料。通过利用活性的丙二酸亚异丙酯为起始原料,与十二醇进行酯化反应,高收率的制备了丙二酸单十二烷基酯中间体,再与5,5-二羟甲基环戊[c]并噻吩反应,生成对称的丙二酸双酯,最后与富勒烯C60进行Bingel反应制备2个富勒烯衍生物,其电化学性质被表征。     

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。     

基于宽带隙聚合物太阳能电池的研究进展

有机太阳能电池因为制备过程简单、重量轻、成本低廉和可制成柔性器件等优点受到了广泛的关注。近年来,随着窄带隙小分子受体材料的快速发展,与之光谱匹配的宽带隙给体聚合物太阳能电池表现出较高的PCE。研究人员通过苯并二噻吩(BDT)、苯并二噻吩-4,8-二酮(BDD)、萘并双三唑和苯并三唑(BTA)等构建块,设计合成了一系列高效的宽带隙给体聚合物。在此对宽带隙聚合物非富勒烯太阳能电池的研究进展进行综述。     

供体—受体型聚合物太阳能电池材料研究进展

有机太阳能电池因其廉价、来源广、柔性、质轻等优势而备受关注,开发性能优异的聚合物给体材料是目前有机太阳能电池的研究热点。介绍了聚合物太阳能电池的基本结构,光电转换理论,综述了供体—受体型聚合物给体材料的研究进展,并对聚合物太阳能电池的发展方向进行了展望。     

含长碳链富勒烯衍生物的制备与表征

为了改善有机太阳能电池的光电特性,本文设计一种溶解性良好的富勒烯衍生物作为电池的受体材料。以对苯二酚和溴代正辛烷为原料制备对辛烷氧基苯酚中间体,再与丙二酸环亚异丙酯反应合成丙二酸单酯,进一步与十二醇酯化合成不对称丙二酸双酯,最后与富勒烯(C60)进行Bingel反应制备了含长碳链的富勒烯衍生物目标物,该化合物结构与电化学性质完全被表征。     

缓冲层在有机太阳能电池中的应用

有机太阳能电池的有机活化层与阴、阳极接触界面的性质对器件性能起着重要的作用。本文综述了近年来有机太阳能电池中使用的阴、阳极界面缓冲材料的类型和工作机制。结果表明,阴、阳极缓冲层的界面修饰对太阳能电池的能量转换效率、寿命和稳定性具有决定性的影响。因此,缓冲层的特性研究对器件结构的改进和性能优化具有一定的指导意义。该研究为其它缓冲层材料在有机太阳能电池中的成功应用提供了有益的实验思路。     

Organic solar cell materials and active layer designs—improvements with carbon nanotubes: a review

Organic solar cells offer an opportunity to diversify renewable energy sources owing to their low technological cost. They are amenable to large surfaces and can easily be integrated into buildings. It is necessary, however, to improve their energy efficiency and durability for the development of a sustainable technology. In these devices, photovoltaic conversion is based on the separation of photogenerated charges at an interface between electron donor and acceptor materials, which imposes some constraints on the photoactive layer of the cells. In this paper, which includes some of our studies, we address optimization of the active layer: absorption and exciton dissociation steps, the open‐circuit voltage and the active layer morphology. A promising direction proposed to improve the active layer morphology and cell efficiency is the incorporation of highly anisotropic nanoparticles such as carbon nanotubes, which may facilitate charge transport to the electrodes. Dispersion and orientation of the nanotubes in the organic matrix are discussed and we suggest an ideal model polymer solar cell which will maximize performance of the cells by using carbon nanotubes in the active layer. Copyright © 2012 Society of Chemical Industry     

Molecular design of interfacial layers based on conjugated polythiophenes for polymer and hybrid solar cells

In the past two decades, bulk heterojunction organic photovoltaic (OPV) devices have emerged as attractive candidates for solar energy conversion due to their lightweight design and potential for low‐cost, high‐throughput, solution‐phase processability. Interfacial engineering is a proven efficient approach to achieve OPV devices with high power conversion efficiencies. This mini‐review provides an overview of the key structural considerations necessary when undertaking the molecular design of conjugated polyelectrolytes, for application as interfacial layers (ILs). The different roles of ILs are outlined, together with the advantages and disadvantages of competing classes of IL materials. Particular emphasis is placed on the design and synthesis of water‐soluble polythiophene‐based IL materials and the influence of their structural characteristics on their performance as a promising class of IL material. Finally, the challenges and opportunities for polythiophenes as IL materials for OPV devices and other solution‐processed solar cell technologies (e.g. perovskite solar cells) are discussed. © 2017 Society of Chemical Industry     

Carbon nanotube incorporation: A new route to improve the performance of organic–inorganic heterojunction solar cells

Incorporation of oxidized camphoric multi-walled carbon nanotubes (MWCNs) in the polymer layer of regioregular poly(3-octylthiophene)/n-Si heterojunction solar cell is observed to improve the performance of the device by many folds. We report power conversion efficiency, open circuit voltage, short-circuit current density, and fill factor of 0.175%, 0.22 V, 2.915 mA/cm², 0.27 respectively, for an un-optimized cell containing MWCNs. Reference cells without MWCNs show much lower performance. Improved device performance is due to better hole transport, easy exciton splitting and suppression of charge carrier recombination as a result of incorporation of MWCNs. MWCNs, being low cost materials, seem to be promising materials for improving device performance of organic–inorganic heterojunction solar cells.     

Theoretical evaluation of chemical substitutions along the main chain of poly(3‐hexylthienylene‐vinylene) for solar cell applications

In order to improve the efficiency of bulk‐heterojunction organic solar cells, one can try to optimize the active layer through the use of new materials that provide improvements in the parameters that influence the final efficiency of a device. The use of chemical substitutions in organic materials already used in these devices seems to be an efficient methodology to obtain new materials with better intrinsic properties. Based on this idea, in this work is investigated theoretically, by methods of electronic structure calculation, a set of 143 poly(3‐hexylthienylene‐vinylene) (P3HTV) derivatives for application in active layers of organic solar cells as electron donor materials; the chemical modifications were performed on the thiophene ring and the vinyl segment of P3HTV. The results show that it is possible to obtain several new derivatives with better optical and electronic properties than those of P3HTV. The derivative substituted with trifluoromethyl on the vinyl segment is one of the most promising for use in active layers, when combined with phenyl‐C61‐butyric‐acid‐methyl‐ester as electron acceptor material. An equation to predict the electronic properties of P3HTV derivatives when using more than one chemical substitution is also proposed, which is corroborated by the theoretical calculations. © 2017 Society of Chemical Industry     

Solution-processed, nanostructured hybrid solar cells with broad spectral sensitivity and stability

Hybrid organic-inorganic solar cells, as an alternative to all-organic solar cells, have received significant attention for their potential advantages in combining the solution-processability and versatility of organic materials with high charge mobility and environmental stability of inorganic semiconductors. Here we report efficient and air-stable hybrid organic-inorganic solar cells with broad spectral sensitivity based on a low-gap polymer poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) and spherical CdSe nanoparticles. The solvents used for depositing the hybrid PCPDTBT:CdSe active layer were shown to strongly influence the film morphology, and subsequently the photovoltaic performance of the resulted solar cells. Appropriate post-deposition annealing of the hybrid film was also shown to improve the solar cell efficiency. The inclusion of a thin ZnO nanoparticle layer between the active layer and the metal cathode leads to a significant increase in device efficiency especially at long wavelengths, due to a combination of optical and electronic effects including more optimal light absorption in the active layer and elimination of unwanted hole leakage into the cathode. Overall, maximum power conversion efficiencies up to 3.7 ± 0.2% and spectral sensitivity extending above 800 nm were achieved in such PCPDTBT:CdSe nanosphere hybrid solar cells. Furthermore, the devices with a ZnO nanoparticle layer retained ～70% of the original efficiency after storage under ambient laboratory conditions for over 60 days without any encapsulation.     

Efficiency of bulk-heterojunction organic solar cells

During the last years the performance of bulk heterojunction solar cells has been improved significantly. For a large-scale application of this technology further improvements are required. This article reviews the basic working principles and the state of the art device design of bulk heterojunction solar cells. The importance of high power conversion efficiencies for the commercial exploitation is outlined and different efficiency models for bulk heterojunction solar cells are discussed. Assuming state of the art materials and device architectures several models predict power conversion efficiencies in the range of 10–15%. A more general approach assuming device operation close to the Shockley–Queisser-limit leads to even higher efficiencies. Bulk heterojunction devices exhibiting only radiative recombination of charge carriers could be as efficient as ideal inorganic photovoltaic devices.     

Investigation of bulk hybrid heterojunction solar cells based on Cu(In,Ga)Se2 nanocrystals

This work presents the systematic studies of bulk hybrid heterojunction solar cells based on Cu(In, Ga)Se₂ (CIGS) nanocrystals (NCs) embedded in poly(3-hexylthiophene) matrix. The CIGS NCs of approximately 17 nm in diameter were homogeneously blended with P3HT layer to form an active layer of a photovoltaic device. The blend ratios of CIGS NCs to P3HT, solvent effects on thin film morphologies, interface between P3HT/CIGS NCs and post-production annealing of devices were investigated, and the best performance of photovoltaic devices was measured under AM 1.5 simulated solar illumination (100 mW/cm²).     

High Efficiency Computer Simulation for Au/n-ZnO/p-Si/Al Schottky-Type Thin Film Heterojunctions

In this paper, the Au/n-ZnO/p-Si/Al heterojunction for developing solar cells with high conversion efficiency and low cost were studied. The Au/n-ZnO/p-Si/Al HIT (heterojunction with intrinsic thin-layer) solar cells were analyzed and designed by AFORS-HET software. The characteristics of such cells with emitter intrinsic layer thickness and interface states density are discussed. The simulation results show that the key role of the intrinsic layer inserted between the ZnO and crystalline silicon substrate p-Si is to decrease the interface states density. If the interface states density is lower than 10¹⁰ cm^?2.V^?1, a thinner intrinsic layer is better than a thicker one. The increase of the thickness of the emitter will decrease the short-current density and affect the conversion efficiency. The effect of Surface Recombination Velocity (SRV) front and back on the J-V characteristics of the Au/n-ZnO/p-Si/Al heterojunction solar cell has been studied with this simulation. With the optimized parameters set, the Au/n-ZnO/p-Si/Al solar cell reaches a high efficiency (η) up to 21.849 % (FF: 0.834, V_oc: 0.666 V, J_sc: 39.39 mA/cm²).     

The influence of additive property on performance of organic bulk heterojunction solar cells

The performance of bulk heterojunction organic solar cells based upon blends of donor and acceptor materials has been shown to be highly dependent on the microstructure and photoelectric properties of active layer. Recently, various methods, such as post-annealing, microwave annealing and control in the film-forming rate, and so on, have been used to modify the morphology to achieve high device performance. Among these methods, adding additives is a simple and promising approach, which can not only control the morphology but also improve the photon absorption or energy-level distribution of the active layer. In this review, we will introduce the additives that used widely in recent from following aspects: species, mechanism, and performance. First, the additive species and its selection principle according to special donor and acceptor system will be concluded. Then, the mechanisms of improved morphology and photoelectric properties by adding different kinds of additives will be illustrated in brief. At last, we will discuss the influences of additives on device performance.