- Fluorene Side-Chained Benzodithiophene Polymers for Low Energy Loss Solar Cells
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Here we design and synthesize one novel fluorene side-chained benzodithiophene (BDT) monomer for polymer solar cells (PSCs) donor. By copolymerizing this monomer with 4,7-di(thiophen-2-yl)-2,1,3-benzothiadiazole (DTBT) or 4,7-di(4-(2-ethylhexyl)-2-thienyl)-5,6-difluoro-2,1,3-benzothiadiazole (DTffBT), two donor-acceptor (D-A) conjugated polymers PFBDT-DTBT and PFBDT-DTffBT are prepared. PSCs are prepared with these polymers as donor and PC71BM as acceptor. The maximum power conversion efficiency (PCE) of the two polymers PFBDT-DTBT and PFBDT-DTffBT based PSCs is 7.13% (VOC = 0.90 V, JSC = 13.26 mA cm-2, and FF = 0.598) and 7.33% (VOC = 0.96 V, JSC = 13.24 mA cm-2, and FF = 0.577). The UV-vis absorption and electrochemical cyclic voltammetry test results show that F atoms in DTffBT unit present an obvious influence on intermolecular effect and molecular energy levels of polymers. Furthermore, the energy loss of two PSCs devices in this work is confirmed to be 0.78 and 0.71 eV, lower than most results based on BDT PSCs devices, which is critical to obtain high PCE PSCs devices with a decent trade-off between JSC and VOC.
- Song, Xin,Zhang, Yongchao,Li, Yonghai,Li, Feng,Bao, Xichang,Ding, Dakang,Sun, Mingliang,Yang, Renqiang
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- Synthesis, optical, and electrochemical properties of 4-fluorophenyl end-capped oligofluorenes
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This paper presents a series of oligofluorenes mainly based on 9,9-bis(2-ethylhexyl)fluorene units whose rigid core has been extended with 4-fluorobenzene termini. Thermogravimetric analysis, differential scanning calorimetry, absorption spectra, photolum
- Huang, Yi-Bing,Cui, Yu,Zeng, Liu-Fang,Shen, You-Yu,Feng, Ling-Zhu,Shi, Xue-Feng,Ye, Li-Yi,Yin, Ying-Wu,Tu, Song
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p. 195 - 201
(2015/08/19)
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- Synthesis and photovoltaic properties of conjugated copolymers bearing bis(9,9-di(2-ethylhexyl)-9H-fluoren-2-yl)quinoxaline subunit with deep HOMO level
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A series of alternating copolymers (PT-BDFQx, PC-BDFQx and PBDT-BDFQx) have been synthesized bearing novel planar bis(9,9-di(2-ethylhexyl)-9H-fluoren-2-yl)quinoxaline (BDFQx) as acceptor unit, using benzo[1,2-b:4,5-b′]dithiophene (BDT), thiophene (T) and carbazole (C) as donor units via Stille or Suzuki coupling reactions. XRD characterization indicated that the presence of planar BDFQx unit (monomer 8) is favorable for the promotion of crystallization in the solid state and GPC results illustrated that the import of multiple chains in planar BDFQx unit raises the polymers molecular weight. Electrochemical measurement results suggested that three copolymers possess deep HOMO energy level of -5.50-5.77 eV. The polymer solar cell with structure of ITO/PEDOT:PSS (30 nm)/polymer: PCBM (60 nm)/Bphen (10 nm)/Ag (100 nm) exhibited the highest Voc of 0.80 V with PBDT-BDFQx as p-type polymer, while the best power conversion efficiency (PCE) of 0.9% was obtained using a blend of PBDT-BDFQx and PCBM(1:4) as active layer.
- Chen, Jing,Deng, Xianping,Yang, Daobin,Huo, Erfu,Chen, Yunqing,Huang, Yan,Lu, Zhiyun
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p. 5959 - 5966
(2015/02/19)
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- Synthesis and characterization of monodisperse oligofluorenes
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An efficient synthesis of 9,9-bis(2-ethylhexyl)fluorene oligomers up to the heptamer is reported, with repetitive Suzuki and Yamamoto coupling reactions employed in the synthesis. The key steps for preparation of the essential intermediates include Pd-catalyzed transformation of aryl bromides to aryl boronic esters (Miyaura reaction) and the application of the much higher reactivity of aryl boronic esters over aryl bromides in the Pd-catalyzed cross-coupling reaction with aryl diazonium salts. Variation of the UV/Vis absorption and photoluminescence characteristics with chain length is reported. Moreover, glass transition and liquid-crystal characteristics of the oligomers are described and compared with those of the polymer.
- Jo, Jungho,Chi, Chunyan,Hoeger, Sigurd,Wegner, Gerhard,Yoon, Do Y.
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p. 2681 - 2688
(2007/10/03)
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