- An efficient strategy to supervise absorption, mobility, morphology of photovoltaic molecule by inserting a D-A unit
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The absorption, mobility and morphology of molecules in the active layer have a crucial influence on photovoltaic properties of organic solar cells. In this work, we design an A1-(D-A)2-D-A1 type oligomer DRCN4FBT on the basis of an A1-D-A-D-A1 type small molecule DRCN2FBT by inserting D-A unit. It is found that oligomer DRCN4FBT exhibits wider absorption spectrum and higher carrier mobility and better morphology than small molecule DRCN2FBT in active layer using fullerene PC71BM as acceptor. The absorption and energy level, mobility, morphology of DRCN4FBT in active layer are well supervised by inserting D-A unit in DRCN2FBT. As a result, its power conversion efficiency and short current density are increased by about 20% for the DRCN4FBT/PC71BM based organic solar cells in comparison with the DRCN2FBT/PC71BM based devices. It indicates that simply increasing D-A unit in small molecules to construct oligomer is an efficient strategy to improve photovoltaic properties.
- Gu, Ziqian,Guo, Jiali,Hao, Rulin,Lin, Zixuan,Qian, Yu,Ma, Chao,Fan, Yankai,Deng, Xiaoyuan,Zhang, Guangjun,Peng, Wenhong,Xia, Hao,Peng, Qiang,Zhu, Weiguo
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- Effects of conformational symmetry in conjugated side chains on intermolecular packing of conjugated polymers and photovoltaic properties
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Introducing conjugated side chains onto the backbone of two-dimensionally (2D) conjugated polymers has been utilized for tuning the optoelectronic characteristics of the polymer and the morphological properties of organic photovoltaics. To investigate the effects of conformational symmetry of conjugated side chains, two benzo[1,2-b:3,4-b′]dithiophene (BDT)-based derivatives, one with the asymmetric alkoxythienyl (Th) side chain and the other with the symmetric alkoxyphenyl (Ph) side chain, were synthesized as donor units and copolymerized with fluorinated benzothiadiazole (2FBT). These two side chains were selected for the distinct differences between their structures, and were found to affect the intrinsic characteristics of these BDT polymers. The introduction of the symmetric conjugated side chain to the conjugated backbone of the polymer was observed to improve both light harvesting and the charge carrier mobility, apparently by increasing the extent of packing between the polymer chains. Power conversion efficiency (PCE) values of photovoltaic devices fabricated using these conjugated polymers were strongly related to the light absorbance and crystallinity in a film of the blend of polymer and [6,6]-phenyl C71-butyric acid methyl ester (PC71BM). PBDT2FBT-Ph showed effective light absorption, an optimum morphology that we argue is due to the symmetry of the conjugated Ph side chain, and a maximum PCE of 6.23%, with an open-circuit voltage of 0.83 V, a short-circuit current density of 11.33 mA cm-2, and a fill factor of 66.3%. These results demonstrate that symmetric conjugated side chains are promising groups to produce 2D-conjugated polymers for high-performance photovoltaics. This systematic study of side chain engineering provides a valuable strategy to synthesize 2D conjugated polymers and to achieve high PCE values in organic photovoltaics.
- Shin, Jisoo,Kim, Min,Lee, Jaewon,Sin, Donghun,Kim, Heung Gyu,Hwang, Hyeongjin,Cho, Kilwon
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p. 106044 - 106052
(2015)
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- Novel donor-acceptor polymers containing: O -fluoro- p -alkoxyphenyl-substituted benzo[1,2- b:4,5- b ′]dithiophene units for polymer solar cells with power conversion efficiency exceeding 9%
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In this work, a new electron-rich building block, o-fluoro-p-alkoxyphenyl-substituted benzo[1,2-b:4,5-b′]dithiophene (BDT) unit, has been used to construct donor (D)-acceptor (A) conjugated copolymers with electron-deficient units 5,6-difluoro-4,7-di(4-(2
- Wang, Ning,Chen, Weichao,Shen, Wenfei,Duan, Linrui,Qiu, Meng,Wang, Junyi,Yang, Chunming,Du, Zhengkun,Yang, Renqiang
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- A 5.6 and heterocyclic - hetero aromatic ring structure of synthetic method
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The invention relates to a synthetic method of a fluorobenzoheterocycle-heteroaromatic ring structure. Specifically, according to the method, simple fluoro-substituted benzoheterocycle, a derivative of the fluoro-substituted benzoheterocycle and a heteroaromatic ring compound are taken as raw materials to prepare various fluoro-substituted benzoheterocycle-heteroaromatic ring compounds at a high yield by taking silver salt as an oxidant by the catalytic effect of palladium salt. By taking simple fluoro-substituted benzoheterocycle and the heteroaromatic ring compound as the raw materials, the method has the advantages of being low in amount of a used catalyst, wide in substrate application range, simple and convenient to operate, high in reaction efficiency and the like. The obtained fluoro-substituted benzoheterocycle-heteroaromatic ring building blocks have wide application in aspects of organic semiconductors, photoelectric materials and solar batteries.
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Paragraph 0211-0213
(2018/02/22)
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- Two-dimensionally extended π-conjugation of donor-acceptor copolymers via oligothienyl side chains for efficient polymer solar cells
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A series of two-dimensional conjugated polymers containing π-conjugated oligothienyl side chains, namely PBDT2FBT-T1, PBDT2FBT-T2, PBDT2FBT-T3, and PBDT2FBT-T4, was designed and synthesized to investigate the effect of two-dimensionally extended π-conjugation on the polymer solar cell (PSC) performance. The oligothienyl units introduced into the side chains significantly affect the optoelectronic properties of the parent polymers as well as the performances of the resulting solar cell devices by altering the molecular arrangement and packing, crystalline behavior, and microstructure of the polymer:PC71BM blend films. The crystallinity and blend morphology of the polymers can be systematically controlled by tuning the π-conjugation length of side chains; PBDT2FBT-T3 exhibited the most extended UV/vis light absorption band and the highest charge mobility, leading to a high short-circuit current density up to 12.5 mA cm-2 in the relevant PSCs. The PBDT2FBT-T3:PC71BM-based PSC exhibited the best power conversion efficiency of 6.48% among this series of polymers prepared without the use of processing additives or post-treatments. These results provide a new possibility and valuable insight into the development of efficient medium-bandgap polymers for use in organic solar cells.
- Lee, Jaewon,Kim, Joo-Hyun,Moon, Byungho,Kim, Heung Gyu,Kim, Min,Shin, Jisoo,Hwang, Hyeongjin,Cho, Kilwon
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p. 1723 - 1735
(2015/03/31)
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- Fluorinated benzothiadiazole-based conjugated polymers for high-performance polymer solar cells without any processing additives or post-treatments
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Thanks to their many favorable advantages, polymer solar cells exhibit great potential for next-generation clean energy sources. Herein, we have successfully designed and synthesized a series of new fluorinated benzothiadiazole-based conjugated copolymers PBDTTEH-DT HBTff (P1), PBDTTEH-DTEHBTff (P2), and PBDTHDO-DTHBTff (P3). The power conversion efficiencies of 4.46, 6.20, and 8.30% were achieved for P1-, P2-, and P3-based devices within ～100 nm thickness active layers under AM 1.5G illumination without any processing additives or post-treatments, respectively. The PCE of 8.30% for P3 is the highest value for the reported traditional single-junction polymer solar cells via a simple fabrication architecture without any additives or post-treatments. In addition, it is noteworthy that P3 also allows making high efficient polymer solar cells with high PCEs of 7.27 and 6.56% under the same condition for ～200 and ～300 nm thickness active layers, respectively. Excellent photoelectric properties and good solubility make polymer P3 become an alternative material for high-performance polymer solar cells.
- Wang, Ning,Chen, Zheng,Wei, Wei,Jiang, Zhenhua
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p. 17060 - 17068
(2013/12/04)
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- Development of fluorinated benzothiadiazole as a structural unit for a polymer solar cell of 7% efficiency
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High-powered polymer: Fluorinated benzothiadiazole was incorporated into a polymer that was used in a high-performance solar cell. The model polymer 2 has decreased HOMO and LUMO energy levels and a similar band gap when compared with its nonfluorinated analogue 1. A bulk heterojunction device derived from 1 demonstrated a high power conversion efficiency of 7.2% (5.0% for 1). (Chemical Equation Presented).
- Zhou, Huaxing,Yang, Liqiang,Stuart, Andrew C.,Price, Samuel C.,Liu, Shubin,You, Wei
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p. 2995 - 2998
(2011/05/05)
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