Dan Lu

Jilin University, Yung-chi, Jilin Sheng, China

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Publications (48)175.85 Total impact

  • Bo Liu · Feng Xu · Xinghua Zhang · Dadong Yan · Dan Lu
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    ABSTRACT: A Pauli master equation method is adopted for the simulation of polymer bulk heterojunction (BHJ) solar cells with Vinylidene fluoride-trifluoroethylene copolymer (P(VDF-TrFE)) film as interfacial layers. According to previous reports, using highly crystalline P(VDF-TrFE) film as interfacial layers can highly enhance the efficiency of polymer BHJ solar cells, and possible mechanisms for the enhancement by two different groups were given as the dipole induced permanent internal electric field or simply the electrodes improvement which implied the origin is barrier lowing effect. The correlation between appearance of S-shaped current density-voltage (J-V) characteristics and energy barrier is studied first, and then further results indicate that the previous electrode improvement model provides a consistent explanation for the origin of performance enhancement due to inserting polarized P(VDF-TrFE) interfacial layers. Moreover, the phenomenon of increase of internal electric field observed before can be attributed to better contact condition which help reduce bimolecular recombination rate. Comparatively speaking, electrode improvement model can give a more rational explanation for the origin of performance enhancement experimentally found. On the contrary, the dipole induced permanent internal electric field model was not complete enough.
    No preview · Article · Jan 2016 · Physical Chemistry Chemical Physics
  • Bo Liu · Feng Xu · Xinghua Zhang · Dadong Yan · Dan Lu
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    ABSTRACT: Based on a full device model adopting three-dimensional Pauli master equation approach, the charge carrier loss process due to poor extraction channels between electrode and active layer in polymer bulk heterojunction(BHJ) solar cells was studied. The influence of barrier height on device performance was simulated to reveal the importance of electrode improvement. It was found that relatively large extraction barrier height(over 0.40 eV) can lead to the significant diminishing of the overall charge collection efficiency, since bimolecular recombination rate would increase to a high level due to enhanced space charge accumulation effect near electrodes. In contrast, the percentage of charge carrier annihilated due to geminate recombination did not change significantly with barrier height variation. Our simulation results may provide the basis for a more accurate model and potential direction of polymer BHJ solar cells improvement. © 2015, Jilin University, The Editorial Department of Chemical Research in Chinese Universities and Springer-Verlag GmbH.
    No preview · Article · Sep 2015 · Chemical Research in Chinese Universities
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    Full-text · Dataset · Aug 2015
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    ABSTRACT: In this work, the solvent field and temperature are used to explore the mutual transformation dynamic process and mechanism between the α-conformation and β-conformation in Poly(9,9-dioctylfluorene) (PFO) precursor solution. The conformational transformation of PFO chain is researched by UV-vis absorption spectra and the proportions of β-conformation are quantitatively calculated. The corresponding variation trend of aggregation structure is researched by using static and dynamic light scattering (SLS/DLS) method. It is found that the mutual transformation process between α-conformation and β-conformation are reversible in essence. Especially in the transformation processes, the complicated relationship between the β-conformation and aggregation structure is understood, that is the aggregation structure make β-conformation formed under solvent field, then the conformational transformation of β-conformation promotes the dissociation of aggregation structure under temperature. The above results give an insight into the β-conformation and aggregation structure of PFO in theory. Furthermore, under the temperature, we find that both two transformation steps have good linear correlations, which indicates that using temperature can be considered as a good method to accurately control the proportion of β-conformation in actual application, and it will help us to get the desired proportion of β-conformation in PFO precursor solution so as to make the charge carrier mobility of optoelectronic films increased and device performance better.
    Preview · Article · Feb 2015 · Soft Matter
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    ABSTRACT: In this work, the α-conformation (individual locally separated chain) of conjugated polymer poly(9,9-dioctylfluorene) (PFO) in dilute solution is studied by the following three points: Mark-Houwink exponent a, fractal dimension D and form factor Rg/Rh. From the result of a, α-conformation of PFO is considered to have a semi-rigid chain conformation in dilute solution. We establish the mathematical relationship between Mark-Houwink exponent a and fractal dimension D in dilute solution. To prove the rationality of this mathematical relationship, the classic polymer polystyrene (PS) is used for comparison. According to the result of D, it can be known that α-conformation of PFO has relatively loose and extended chain conformation. Moreover, we use light-scattering to get the form factor Rg/Rh of the PFO solution in which the α-conformation and β-conformation coexist. It is found that Rg/Rh increase with the content of α-conformation, which indicates that α-conformation of PFO has a loose and extended chain conformation, and this result agrees well with the conclusions drawn from a and D. Based on the fact that β-conformation (ordered conformation) and α-conformation of PFO can transform into each other in solution, this work is significant for the control of β-conformation and will have a potential meaning to increase the charge carrier mobility and efficiency from the PFO solution to films.
    No preview · Article · Jan 2014 · The Journal of Physical Chemistry B
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    ABSTRACT: Two new ceramides, (3S,4S,5R)-3-octadecanoylamino-4-hydroxy-5-dodecane-2,3,4,5-tetrahydrofuran (1) and (3S,4S,5R)-3-[(2R)-2-hydroxyhexacosanoylamino]-4-hydroxy-5-[(4E)-dodecane-4-ene]-2,3,4,5-tetrahydrofuran (2), together with eight known compounds, eleutheroside A (3), eleutheroside B (4), eleutheroside E (5), 7-hydroxy-6-methoxy-coumarin (6), 6,7-dimethoxycoumarin (7), 5α,8α-epidioxyergosta-6,22-dien-3-ol (8), stigmasterol (9) and rutin (10), were isolated from the fruit pulp of Acanthopanax senticosus (Rupr. et Maxim) Harms. Their structures were elucidated by means of physicochemical properties and spectroscopic methods (1D, 2D NMR and MS).
    No preview · Article · Nov 2013 · Natural product research
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    ABSTRACT: Two new dammarane-type compounds were isolated from the leaves and stems of Panax quinquefolium L. The new compounds were named as pseudo-ginsenoside RT6 (1) and pseudoginsengenin R1 (2). The structures of the new compounds were elucidated by the combined analysis of NMR and HR-ESI-MS as (20S,24R)-6-O-β-d-glucopyranosyl-dammar-3-one-20,24-epoxy-6α,12β,25-triol (1) and (20S,24R)-dammar-3-one-20,24-epoxy-6α,12β,25-triol (2).
    No preview · Article · Sep 2013 · Journal of Asian natural products research
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    Full-text · Dataset · Jan 2013
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    ABSTRACT: Ethnopharmacological relevance: Ginseng has been widely used for hundreds of years in both China and other countries. It is well accepted that the pharmacological effects of ginseng are attributed to ginsenosides. Ginsenoside Re is one of the active ingredients in ginseng. The present study was carried out to characterize the toxicity of ginsenoside Re after repeated oral administration in Sprague-Dawley rats. Materials and methods: Rats (60 males, 60 females) were administrated ginsenoside Re orally in 0, 38, 113, or 375 mg/kg/day doses for 26 weeks (n=15/group each sex). Clinical signs, mortality, body weights, feed consumption, urinalysis, hematology, serum biochemistry, gross findings, organ weights and histopathology were examined at the end of the test period, as well as after the 4-week recovery period. Results: Ginsenoside Re did not induce death, adverse effects or dose-dependent changes in feed consumption, or body weight gain. Some statistically significant differences were observed in hematological and biochemical parameters, as well as in body weights of rats treated with ginsenoside Re. However, there was no abnormality of any organs noted in both gross and histopathological examinations. Conclusions: Ginsenoside Re is well tolerated up to a 375 mg/kg/day oral dosage level and non-toxic in both male and female rats.
    No preview · Article · Oct 2012 · Journal of ethnopharmacology
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    ABSTRACT: An efficient and controllable approach to prepare cross-linked films from a conjugated polymer precursor by electrochemical deposition (ED) is reported for the first time. A novel polymer precursor with high solubility, high electroactivity, and electron-transport ability has been designed. The electrochemically deposited polymer film shows high thickness, smooth morphology, and high fluorescence. The single-layer pure-blue-emitting ED PLED exhibits a luminous efficiency of 3.8 cd A(-1) .
    Full-text · Article · May 2012 · Advanced Materials
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    ABSTRACT: In this work, the effects of solvation and desolvation on the β phase of poly(9,9-dioctylfluorene) (PFO) are studied. The content of β phase is approximately calculated for comparison. The content of β phase can be enhanced up to 40% by the solvation effect and become a metastable state; the desolvation effect is a dynamic process and can enhance the content of β phase remarkably by 18%age units. It is found that the contents of β phase are always changing with the aggregation degrees of PFO chains. To fully understand it, the concepts of mesoscopic aggregates and macroscopic aggregates are proposed and well proved by the filtration experiment. In the solution (the ethanol content less than 30%), the mesoscopic aggregates are beneficial to enhance the content of β phase; in the solution (the ethanol content more than 40%), which is close to the condensed state of fabricated optoelectronic film, the macroscopic aggregates can make the content of β phase not only much higher but also stable. The content of β phase can be controlled by changing the aggregation characteristics of PFO chains in solution. This work will be significant in fabricating the optoelectronic devices from solutions to films with high carrier mobility and good stability.
    No preview · Article · Apr 2012 · The Journal of Physical Chemistry C
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    ABSTRACT: Bacterial cellulose (BC), produced by Gluconacetobacter xylinum, consists of ribbon-shaped nano-fibers in web-like structures. Polyaniline (PAni) is a conductive polymer, the conductivity of which is related to the synthesis and doping process. In this paper, we report on the in situ nano-assembly of BC nanofibers and PAni to enhance the electronic conductivity. PAni could be synthesized on the surface of BC nano-fibers and assembled into a novel 3D network. The reaction time of polymerization, the types and concentration of doping protonic acids play a major role on the electroconductivity properties of the composites. The electroconductivity of composite hydrogels was enhanced from 10−8 to 10−2 S cm−1, and can be further improved by doping with various protonic acids. The BC-PAni nanofiber composite is an electro-conductive hydrogel that combines the properties of hydrogels and conductive systems, and it may potentially be used for flexible displays, biosensors, and platform substrates to study the effect of electrical signals on cell activity, and to direct desirable cell function for tissue engineering applications.
    No preview · Article · Feb 2012 · RSC Advances
  • Jin-Ping Liu · Dan Lu · Ping-Ya Li
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    ABSTRACT: One novel hexanordammarane glycoside, ginsenoside R(10), was isolated from the leaves and stems of Panax quinquefolium L. as a minor constituent. It is the first time that a hexanordammarane glycoside isolated from the plant of Panax quinquefolium L. Its structure was elucidated as 3-O-β-D-glucopyranosyl-3β, 12β-dihydroxy-22, 23, 24, 25, 26, 27-hexanordammarane-20-one (1), by the combination analysis of one-dimensional NMR, two-dimensional NMR and mass spectrometry.
    No preview · Article · Oct 2011 · Natural product research
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    ABSTRACT: A new ocotillol-type triterpenoid saponin, named 20(R)-pseudoginsenoside F(11) (1), was isolated along with pseudoginsenoside F(11) (2) from red American ginseng. The structure of the new saponin was elucidated as 6-O-[α-L-rhamnopyranosyl-(1 → 2)-β-D-glucopyranosyl]-dammar-20R, 24R-epoxy-3β, 6α, 12β, 25-tetraol by a combination analysis of NMR and mass spectrometry. The complete signal assignments of the two compounds were carried out by means of 2-D NMR spectral analysis.
    No preview · Article · Oct 2011 · Natural product research
  • Dan Lu · Pingya Li · Jinping Liu
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    ABSTRACT: Six triterpenoid saponins, including one new compound, quinquenoside F₆(1), and five known compounds ginsenoside Re, ginsenoside Rg₁, ginsenoside Rg₂, ginsenoside Rh₁ and pseudo-ginsenoside F₁₁, were isolated from the fruits of Panax quinquefolium L., and the structure of compound 1 was elucidated as 6-O-β-d-glucopyranosyl-20-O-[α-l-arabino- furanosyl-(1-6)-β-d-glucopyranosyl]-dammar-24-ene-3β, 6α, 12β, 20S-tetraol by the combination of the analysis of spectroscopic data and chemical evidences. The complete signal assignments of the six compounds were carried out by means of 2D NMR spectral analysis.
    No preview · Article · Oct 2011 · Natural product research
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    ABSTRACT: In order to further improve the efficiency and stability of luminescent electrochemical polymerization (EP) films and devices, electroactive self-assembled monolayers (SAMs) of carbazolyl alkanethiol are successfully designed and applied to modify Au electrode and covalently graft the deposited EP films. The analysis of the formation and coverage of the SAMs by atomic force microscopy (AFM), cyclic voltammetry (CV), and the theoretical calculation provide consistent results indicating the SAM molecules are densely packed and standing upright (liquid-like) on the Au surface. In addition, ultraviolet photoelectron spectroscopy (UPS), CV, UV, AFM, and sonication treatment reveal that the close-packed electroactive SAMs are effective at enhancing the work function of electrode, increasing the deposition rate of EP precursor as well as elevating the cross-linking efficiency and the adhesive property of subsequent EP films. This is a simple and very efficient method for improving the performance of EP device, which has potential applications in display devices.
    Full-text · Article · Aug 2011 · Advanced Functional Materials
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    ABSTRACT: Two new xanthones, 3-hydroxy-6-methoxy-5'-isopropyl-4',5'-dihydrofuro[2',3' : 7, 8]-6″,6″-dimethyl-4″,5″-dihydropyrano[2″,3″ : 1,2]xanthone (1) and 1,6-dihydroxy-7-methoxy-8-(3-methylbut-3-enyl)-6',6'-dimethyl-4',5'-dihydropyrano[2'3' : 3,2]xanthone (2), were isolated from the pericarp of Garcinia mangostana. Their structures were elucidated by spectral means (1-D and 2-D NMR, MS).
    No preview · Article · Aug 2011 · Natural product research
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    ABSTRACT: This contribution presents a kind of novel and neutral network films based on EDOT formed by in situ electrocopolymerization (ECP). The ECP films which are neutral and colorless exhibit the conductivity of 0.2-0.5 S·cm(-1), W(F) of 4.79-5.20 eV, and RMS roughness of 3.51-5.26 nm. The electroluminescent devices where ECP films acted as hole-transport layer (HTL) exhibit higher brightness, current density, efficiency (20-30% improvement), and stability than that of PEDOT:PSS HTL device. The ECP films also significantly benefit the stability of neighboring organic layer compared to PEDOT:PSS. This kind of new ECP films affords more opportunities to develop organic light-emitting diodes (OLEDs) with high performances and stability.
    Full-text · Article · Jul 2011 · Macromolecular Rapid Communications
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    ABSTRACT: Water-dispersed organic nanoparticles (NPs) constructed by the conjugated molecule 2,5,2',5'-tetra(4'-N,N-diphenylaminostyryl)biphenyl (DPA-TSB) with a high luminescence and large two-photon absorption (TPA) section were fabricated via the reprecipitation method. The average size of the NPs can be controlled from 40 nm to 80 nm by adjusting the reprecipitation conditions. The NPs in water dispersions showed high aggregative and optical stability, which were due to contributions from the special cruciform configuration and amorphous nature of DPA-TSB molecules. The cellular uptake behavior of DPA-TSB NPs was investigated to show their cell staining capabilities as nanoprobes using a confocal microscopy test in vitro. The results demonstrated that DPA-TSB NPs were readily internalized into cytoplasm with no apparent toxicity for up to 24 h, implying excellent imaging capabilities.
    No preview · Article · May 2011 · Nanoscale
  • Jin-Ping Liu · Dan Lu · Ping-Ya Li
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    ABSTRACT: Two new dammarane-type triterpene saponins were isolated from the red American ginseng. The new saponins were named as pseudoginsenoside G(1) and pseudoginsenoside G(2). Their structures were elucidated by the combined analysis of NMR and mass spectrometry as 3-O-[β-d-glucopyranosyl-(1 → 2)-β-d-glucopyranosyl]-dammar-12-one-20S,24R-epoxy-3β,25-diol (pseudoginsenoside G(1)) (1) and 3-O-[β-d-glucopyranosyl-(1 → 2)-β-d-glucopyranosyl]-dammar-12-one-20S,24S-epoxy-3β,25-diol (pseudoginsenoside G(2)).
    No preview · Article · Mar 2011 · Journal of Asian natural products research