- 标题
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In situ Characterization of Phase Transition of Amorphous Poly(9,9-di-n-octyl-2,7-fluorene) Thin Film During Thermal Annealing
摘要： Amorphous poly(9,9-di-n-octyl-2,7-fluorene)(PFO) thin films were characterized in situ via thermal annealing based on grazing incidence X-ray diffraction(GIXRD) profiles, UV-visible absorption spectrophotometry, and Fourier transform infrared spectroscopy(FTIR). The results of GIXRD indicated that the amorphous phase transformed into a crystalline phase when the annealing temperature was higher than 80 °C. Different outcomes were elicited for the intensities and d-spacings of the diffraction peaks below and above 80 °C, which were attributed to the formation of the κ-phase. The mechanism of phase transition was revealed by in situ UV-visible absorption and FTIR spectra, whereby the rearrangement of the side chains was dominant and the movement of the main chains was minimal, even when the annealing temperature was lower than 80 °C. In contrast, the rearrangement of the main chains was dominant when the temperature was higher than 80 °C.
关键词： Liquid crystalline κ-phase,Thermal annealing,Phase transition,Polyfluorene
更新于2025-09-23 15:23:52
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Composite Interlayer Consisting of Alcohol-Soluble Polyfluorene and Carbon Nanotubes for Efficient Polymer Solar Cells
摘要： We report the synthesis of composite interlayers using alcohol-soluble polyfluorene (ASP)-wrapped single-walled carbon nanotubes (SWNTs) and their application as electron transport layers for efficient organic solar cells. The ASP enables the individual dispersion of SWNTs in solution. The ASP-wrapped SWNT solutions are stable for 54 days without any aggregation or precipitation, indicating their very high dispersion stability. Using the ASP-wrapped SWNTs as a cathode interlayer on zinc oxide nanoparticles (ZnO NPs), a power conversion efficiency of 9.45% is obtained in PTB7-th:PC71BM-based organic solar cells, which is mainly attributed to the improvement in the short circuit current. Performance enhancements of 18% and 17% are achieved compared to those of pure ZnO NPs and ASP on ZnO NPs, respectively. In addition, the composite interlayer is applied to non-fullerene-based photovoltaics with PM6:Y6, resulting in the PCE up to 14.37%. The type of SWNT (e.g., in terms of diameter range and length) is not critical to the improvement in the charge-transport properties. A low density of SWNTs in the film (~1 SWNTs/μm2 for ASP-wrapped SWNTs) has a significant influence on the charge transport in solar cells. The improvement in the performance of the solar cell is attributed to the increased internal quantum efficiency, balanced mobility between electrons and holes, and minimized charge recombination.
关键词： interfacial layers,alcohol-soluble polyfluorene,interlayers,organic solar cells,conjugated polyelectrolytes,Carbon nanotubes,electron transport layers,composites
更新于2025-09-23 15:19:57
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Facile Fabrication of Semiconducting Single-Walled Carbon Nanotubes Patterns on Flexible Substrate Based on a Photoimmobilization Technique
摘要： Single-walled carbon nanotubes (SWCNTs) have attracted significant attention due to their outstanding properties. For their wide applications in electronics and optoelectronics, pure semiconducting SWCNTs (s-SWCNTs) and their precise placement are preconditions. Recent advances have focused on developing effective strategies to separate s-SWCNTs from raw SWCNTs, a mixture of metallic and semiconducting SWCNTs, and deposit s-SWCNTs on target substrates. Herein, a polyfluorene-based alternative copolymer (PFBP) containing benzophenone group was employed. PFBP achieved higher yield for s-SWCNTs than the well-studied poly(9,9-dioctylfluore) (PFO) through solution process. Subsequently, the dispersed s-SWCNTs were immobilized on a flexible polyethylene terephthalate (PET) in a facile manner by photoreactive benzophenone group upon exposure to UV irradiation and chemically robust patterns were fabricated from micro to macro scales through photomasks. Our method accomplished by utilizing photoimmobilization is a simple cleaning procedure and an important step forward in pitch scaling for further applications of conjugated polymer wrapped s-SWCNTs.
关键词： nanotubes,photoimmobilization,semiconducting,pattern,carbon,polyfluorene,flexible substrate,single-walled
更新于2025-09-19 17:13:59
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Polyfluorene Copolymers as High‐Performance Hole Transport Materials for Inverted Perovskite Solar Cells
摘要： Inverted perovskite solar cells (PSCs) that can be entirely processed at low temperatures have attracted growing attention owing to their cost-effective production. Hole-transport materials (HTMs) play an essential role in achieving efficient inverted PSCs, as they determine the effectiveness of charge extraction and recombination at interfaces. In this study, three polyfluorene copolymers (TFB, PFB and PFO) were investigated as HTMs for construction of inverted PSCs. It is found that the photovoltaic performance of the solar cells is closely correlated with the electronic properties of the HTMs. Owing to its high mobility along with the favored energy level alignment with perovskite, TFB showed superior charge extraction and suppressed interfacial recombination than PFB- and PFO-based devices, which delivers a high efficiency of 18.48% with an open-circuit voltage (VOC) of up to 1.1 V. In contrast, the presence of a large energy barrier in the PFO-based devices resulted in substantial losses in both VOC and photocurrent. These results demonstrate that TFB could serve as a superior HTM for inverted PSCs. Moreover, we anticipate that the performance of the three HTMs identified here might guide molecular design of novel HTMs for the manufacture of highly efficient inverted PSCs.
关键词： hole-transport materials,charge extraction,polyfluorene copolymers,photovoltaic performance,inverted perovskite solar cells
更新于2025-09-12 10:27:22
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Electron Transport with Mobility, μ > 86 cm2/Vs, in a 74 nm Long Polyfluorene
摘要： The mobility of charges on conjugated polymers is a fundamentally important feature of these materials, but most fall far short of transport that might lead one to call them “molecular wires”. A commonly identified bottleneck is flexible dihedral angles between repeat units. Here we find a very high mobility, μ > 86 cm2/Vs, for electrons attached to polyfluorene polymers in isooctane, despite the presence of varied dihedral angles. The present data suggests that interactions with the surrounding medium may be a principal determinant of charge mobility.
关键词： mobility,molecular wires,conjugated polymers,polyfluorene,electron transport
更新于2025-09-04 15:30:14