太阳能电池新型聚合物给体材料的性能研究

设计合成了新型聚合物给体材料PTT-FTQ,以PTT-FTQ∶PCBM体系作为活性层,研究了给受体比例及膜厚、受体类型、添加剂等因素对有机太阳能电池性能的影响。结果表明,当给受体比例为1∶2时,PTT-FTQ能与受体PC61BM形成良好的网络结构,活性层薄膜表面变得更加光滑平整,在活性层膜厚为120 nm时,有利于吸收光子,传输激子,器件能量转化效率达到2.12%,采用1,8-二碘辛烷(DIO)做添加剂,在添加量为溶剂的1%时,效率提升到2.18%,随着DIO加入量的增加,反而会减少给受体间的界面接触面积,导致激子的解离效率和载流子的传输效率大幅度降低。而采用PC71BM做受体时,电池的短路电流密度比PC61BM体系下的要大得多,但是开路电压会稍低,这主要是PC71BM有较强的光谱吸收但LUMO能级较低,PTT-FTQ∶PC71BM体系能量转化效率达到2.78%。     

基于噻吩-苯非对称单元的DPP类聚合物给体材料的合成及光伏性能

为了优化聚合物太阳能电池的光伏性能,设计合成了一种基于噻吩-苯非对称单元的二酮吡咯并[3,4-c]吡咯(DPP)类聚合物给体材料(PDPP-PT)。非对称结构的设计使得该聚合物具有较好的分子堆积,有利于器件的制备。该聚合物具有范围在300~900nm的宽吸收光谱、1.5eV的窄光学带隙。在器件性能方面,活性层厚度达260nm时,测得开路电压(Voc)为0.68V,光电转换效率(PCE)为1.51%。因此,PDPP-PT给体材料在制备厚活性层太阳能电池时具有一定的优势并为聚合物给体材料的分子设计提供了一种新的思路。     

聚合物在太阳能电池材料中的应用

综述了近年来聚合物在太阳能电池材料中的应用.对电子给体材料和受体材料两类聚合物材料进行详细的描述,并阐述了进一步发展的重点和前景.     

新型窄带隙聚合物太阳能电池材料的合成及性能研究

为了寻找更优异的太阳能电池材料,通过stille偶联反应以2,2′-联噻吩作为给体单元,以4,7-二(3-己基噻吩-2-基)-5,6-二氟-[2,1,3]苯并噻二唑作为受体单元,合成了一种新型聚合物。通过引入支链和氟原子提高了聚合物的性质。利用傅里叶变换红外光谱仪和核磁共振氢谱仪表征了聚合物的结构,采用热重差热综合热分析仪表征了聚合物的热稳定性,并通过紫外-可见吸收光谱和循环伏安法研究了其光电性能。结果表明,聚合物的热分解温度为366℃,带隙为2.16eV,理论开路电压为1.02V,在聚合物太阳能电池的制备中可将其作为给体材料。     

新型窄带隙聚合物太阳能电池光伏材料

聚合物太阳能电池中给体材料的能级水平、带隙、光吸收系数、溶解性、成膜性及载流子迁移率是决定器件性能的关键因素.阐述了聚合物太阳能电池中给体材料的最新研究进展,着重介绍了含有苯并双噻吩的窄带隙D-A类型的共聚物,并对一些给体材料的能级水平优化结果做了简单的总结.最后指出了未来聚合物太阳能电池给体材料今后的发展方向.     

聚合物太阳能电池材料的研究进展

综述了近年来聚合物太阳能电池的研究进展,对电子给体与电子受体两大类聚合物光伏材料进行了详细的描述,并阐述了进一步发展的重点、趋势及前景。     

金属络合物在有机太阳能电池中的应用研究进展

全球性的环境与能源危机已成为可持续发展必须面临的重要问题, 开发清洁可再生能源以替代传统化石能源成为当今社会关注的焦点之一.其中, 利用太阳能电池将太阳能转化为电能是清洁可再生能源领域最有前景的解决方案.在众多太阳能电池技术中, 有机太阳能电池因具有质量轻、原材料来源广泛、成本低、机械柔性好、可采用湿法制备成大面积器件...     

基于噻吩-苯非对称单元的DPP类聚合物给体材料的合成及光伏性能

为了优化聚合物太阳能电池的光伏性能,设计合成了一种基于噻吩-苯非对称单元的二酮吡咯并[3,4-c]吡咯(DPP)类聚合物给体材料(PDPP-PT).非对称结构的设计使得该聚合物具有较好的分子堆积,有利于器件的制备.该聚合物具有范围在300~900 nm的宽吸收光谱、1.5 eV的窄光学带隙.在器件性能方面,活性层厚度达260 nm时,测得开路电压(Voc)为0.68 V,光电转换效率(PCE)为1.51%.因此,PDPP-PT给体材料在制备厚活性层太阳能电池时具有一定的优势并为聚合物给体材料的分子设计提供了一种新的思路.     

氟材料在有机太阳能电池中的应用

有机太阳能电池具有成本低、质量轻、柔韧性好等优点,提高有机太阳能电池的光电转化率和降低成本,开发新型的有机太阳能电池材料一直是研究的重点。文中简要介绍了有机太阳能电池的特点、工作原理及发展趋势,提出了含氟共轭聚合物在有机太阳能电池给体材料中的研究,重点讨论了含氟苯并噻二唑,含氟苯并三唑及1,5-并噻吩衍生物的研究。同时,讨论了含氟物质在界面修饰材料中的应用。最后,对含氟共轭聚合物在有机太阳能电池未来的发展做出了展望。     

Random Polymerization Strategy Leads to a Family of Donor Polymers Enabling Well-Controlled Morphology and Multiple Cases of High-Performance Organic Solar Cells

Developing high-performance donor polymers is important for nonfullerene organic solar cells (NF-OSCs), as state-of-the-art nonfullerene acceptors can only perform well if they are coupled with a matching donor with suitable energy levels. However, there are very limited choices of donor polymers for NF-OSCs, and the most commonly used ones are polymers named PM6 and PM7, which suffer from several problems. First, the performance of these polymers (particularly PM7) relies on precise control of their molecular weights. Also, their optimal morphology is extremely sensitive to any structural modification. In this work, a family of donor polymers is developed based on a random polymerization strategy. These polymers can achieve well-controlled morphology and high-performance with a variety of chemical structures and molecular weights. The polymer donors are D–A1–D–A2-type random copolymers in which the D and A1 units are monomers originating from PM6 or PM7, while the A2 unit comprises an electron-deficient core flanked by two thiophene rings with branched alkyl chains. Consequently, multiple cases of highly efficient NF-OSCs are achieved with efficiencies between 16.0% and 17.1%. As the electron-deficient cores can be changed to many other structural units, the strategy can easily expand the choices of high-performance donor polymers for NF-OSCs.     

High‐Efficiency All‐Small‐Molecule Organic Solar Cells Based on an Organic Molecule Donor with Alkylsilyl‐Thienyl Conjugated Side Chains

Two medium‐bandgap p‐type organic small molecules H21 and H22 with an alkylsily‐thienyl conjugated side chain on benzo[1,2‐b:4,5‐b′]dithiophene central units are synthesized and used as donors in all‐small‐molecule organic solar cells (SM‐OSCs) with a narrow‐bandgap n‐type small molecule 2,2′‐((2Z,2′Z)‐((4,4,9,9‐tetrahexyl‐4,9‐dihydro‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene‐2,7‐diyl)bis(methanylylidene))bis(3‐oxo‐2,3‐dihydro‐1H‐indene‐2,1‐diylidene))dimalononitrile (IDIC) as the acceptor. In comparison to H21 with 3‐ethyl rhodanine as the terminal group, H22 with cyanoacetic acid esters as the terminal group shows blueshifted absorption, higher charge‐carrier mobility and better 3D charge pathway in blend films. The power conversion efficiency (PCE) of the SM‐OSCs based on H22:IDIC reaches 10.29% with a higher open‐circuit voltage of 0.942 V and a higher fill factor of 71.15%. The PCE of 10.29% is among the top efficiencies of nonfullerene SM‐OSCs reported in the literature to date.     

Balanced Partnership between Donor and Acceptor Components in Nonfullerene Organic Solar Cells with >12% Efficiency

Relative to electron donors for bulk heterojunction organic solar cells (OSCs), electron acceptors that absorb strongly in the visible and even near‐infrared region are less well developed, which hinders the further development of OSCs. Fullerenes as traditional electron acceptors have relatively weak visible absorption and limited electronic tunability, which constrains the optical and electronic properties required of the donor. Here, high‐performance fullerene‐free OSCs based on a combination of a medium‐bandgap polymer donor (FTAZ) and a narrow‐bandgap nonfullerene acceptor (IDIC), which exhibit complementary absorption, matched energy levels, and blend with pure phases on the exciton diffusion length scale, are reported. The single‐junction OSCs based on the FTAZ:IDIC blend exhibit power conversion efficiencies up to 12.5% with a certified value of 12.14%. Transient absorption spectroscopy reveals that exciting either the donor or the acceptor component efficiently generates mobile charges, which do not suffer from recombination to triplet states. Balancing photocurrent generation between the donor and nonfullerene acceptor removes undesirable constraints on the donor imposed by fullerene derivatives, opening a new avenue toward even higher efficiency for OSCs.     

Integrated Perovskite/Bulk-Heterojunction Organic Solar Cells

The recently emerged integrated perovskite/bulk-heterojunction (BHJ) organic solar cells (IPOSCs) without any recombination layers have generated wide attention. This type of device structure can take the advantages of tandem cells using both perovskite solar and near-infrared (NIR) BHJ organic solar materials for wide-range sunlight absorption and the simple fabrication of single junction cells, as the low bandgap BHJ layer can provide additional light harvesting in the NIR region and the high open-circuit voltage can be maintained at the same time. This progress report highlights the recent developments in such IPOSCs and the possible challenges ahead. In addition, the recent development of perovskite solar cells and NIR organic solar cells is also covered to fully underline the importance and potential of IPOSCs.     

Highly Efficient All-Small-Molecule Organic Solar Cells with Appropriate Active Layer Morphology by Side Chain Engineering of Donor Molecules and Thermal Annealing

It is very important to fine-tune the nanoscale morphology of donor:acceptor blend active layers for improving the photovoltaic performance of all-small-molecule organic solar cells (SM-OSCs). In this work, two new small molecule donor materials are synthesized with different substituents on their thiophene conjugated side chains, including SM1-S with alkylthio and SM1-F with fluorine and alkyl substituents, and the previously reported donor molecule SM1 with an alkyl substituent, for investigating the effect of different conjugated side chains on the molecular aggregation and the photophysical, and photovoltaic properties of the donor molecules. As a result, an SM1-F-based SM-OSC with Y6 as the acceptor, and with thermal annealing (TA) at 120 °C for 10 min, demonstrates the highest power conversion efficiency value of 14.07%, which is one of the best values for SM-OSCs reported so far. Besides, these results also reveal that different side chains of the small molecules can distinctly influence the crystallinity characteristics and aggregation features, and TA treatment can effectively fine-tune the phase separation to form suitable donor–acceptor interpenetrating networks, which is beneficial for exciton dissociation and charge transportation, leading to highly efficient photovoltaic performance.     

A 3-Fluoropyridine Manipulating the Aggregation and Fibril Network of Donor Polymers for Eco-Friendly Solution-Processed Versatile Organic Solar Cells

The development of eco-friendly solvent-processed organic solar cells (OSCs) suitable for industrial-scale production should be now considered the imperative research. Herein, asymmetric 3-fluoropyridine (FPy) unit is used to control the aggregation and fibril network of polymer blends. Notably, terpolymer PM6(FPy = 0.2) incorporating 20% FPy in a well-known donor polymer poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo[1,2-b:4,5-b’]dithiophene))-alt-(5,5-(1’,3’-di-2-thienyl-5’,7’-bis(2-ethylhexyl)benzo[1’,2’-c:4’,5’-c’]dithiophene-4,8-dione)] (PM6) can reduce the regioregularity of the polymer backbone and endow them with much-enhanced solubility in eco-friendly solvents. Accordingly, the excellent adaptability for fabricating versatile devices based on PM6(FPy = 0.2) by toluene processing is demonstrated. The resulting OSCs exhibit a high power conversion efficiency (PCE) of 16.1% (17.0% by processed with chloroform) and low batch-to-batch variation. Moreover, by controlling the donor-to-acceptor weight ratio at 0.5:1.0 and 0.25:1.0, semi-transparent OSCs (ST-OSCs) yield significant light utilization efficiencies of 3.61% and 3.67%, respectively. For large-area (1.0 cm²) indoor OSC (I-OSC), a high PCE of 20.6% is achieved with an appropriate energy loss of 0.61 eV under a warm white light-emitting diode (3,000 K) with the illumination of 958 lux. Finally, the long-term stability of the devices is evaluated by investigating their structure–performance–stability relationship. This work provides an effective approach to realizing eco-friendly, efficient, and stable OSCs/ST-OSCs/I-OSCs.     

Advances in Solution‐Processed Multijunction Organic Solar Cells

The efficiency of organic solar cells can benefit from multijunction device architectures, in which energy losses are substantially reduced. Herein, recent developments in the field of solution‐processed multijunction organic solar cells are described. Recently, various strategies have been investigated and implemented to improve the performance of these devices. Next to developing new materials and processing methods for the photoactive and interconnecting layers, specific layers or stacks are designed to increase light absorption and improve the photocurrent by utilizing optical interference effects. These activities have resulted in power conversion efficiencies that approach those of modern thin film photovoltaic technologies. Multijunction cells require more elaborate and intricate characterization procedures to establish their efficiency correctly and a critical view on the results and new insights in this matter are discussed. Application of multijunction cells in photoelectrochemical water splitting and upscaling toward a commercial technology is briefly addressed.