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Xia, Yuxin
Publications (10 of 12) Show all publications
Xia, Y. (2018). Polymer/polymer blends in organic photovoltaic and photodiode devices. (Doctoral dissertation). Linköping: Linköping University Electronic Press
Open this publication in new window or tab >>Polymer/polymer blends in organic photovoltaic and photodiode devices
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Organic photovoltaics devices (OPV) have attracted attentions of scientist for their potential as inexpensive, lightweight, flexible and suitable for roll-to-roll production. In recent years, considerable attention has been focused on new acceptor materials, either polymeric or small molecules, to replace the once dominating fullerene derivatives. The emergence of numerous new non-fullerene materials has driven power conversion efficiency (PCE) up to 17%, attracting more and more interests of commercialization.

Polymer acceptors with more morphology stability, more absorption and more desired energy levels has been intensively studied and show great potential for large area and low-cost production in the future. OPV at this moment is not yet competitive with inorganic solar cells in PCE but is more attractive in flexibility, low weight and semitransparency. In this thesis, some basic knowledges of OPV is introduced in the first few chapters, while the next chapters are focusing on polymer-polymer blends and investigating novel structures and techniques for large scale production of solar cells and photodetectors aiming at maximizing these advantages to compete with inorganic counterpart.

Thermal annealing effects on polymer-polymer solar cells based is studied. Annealed devices show doubled power conversion efficiency compared to non-annealed devices. Based on the morphology—mobility examination, we conclude that the better charge transport is achieved by higher order and better interconnected networks of the bulk heterojunction in the annealed active layers. The annealing improves charge transport and extends the conjugation length of the polymers, which do help charge generation and meanwhile reduce recombination. The blend of an amorphous polymer and a semi-crystalline polymer can thus be modified by thermal annealing to double the power conversion efficiency.

A novel concept of all-polymer organic photovoltaics device is demonstrated in this thesis where all the layers are made out of polymers. We use PEDOT:PSS as semitransparent anode and polyethyleneimine modified PEDOT:PSS as semitransparent cathode, both of which are slot-die printed on polyethylene terephthalate(PET). Active layers are deposited on cathode and anode surfaces by spin coating separately. These layers are then joined through a roll-to-roll compatible lamination process. This forms a semitransparent and flexible solar cell. By laminating a thin layer acceptor polymer to a thick polymer-polymer blend, we can further improve the performance by reducing traps comparing to laminating blend to blend.

Flexible and semitransparent all-polymer photodiodes with different geometries can be fabricated through lamination. By choosing high band gap polymers and appropriate combination of two or more polymers, organic photodiode with low noise and high specific detectivity can be obtained. Comparison between bilayer and bulk heterojunction devices gives better understanding of the origin of noise and provides ways to improve the performance of photodiodes as detector.

Noise level is a critical parameter for photodetectors. The difficulties of measuring the noise of photodetectors make some researchers prefer the estimated shot noise as the dominating one and ignore the thermal noise and 1/f noise. The latter two terms are sometimes several orders higher than the former, noting the importance of experimentally measuring noise.

The use of semi-transparent photovoltaic devices causes an inevitable loss of photocurrent, as light transmitted has not been absorbed. This trivial effect also leads to a loss of photovoltage, an effect partially due to the lower photocurrent but also due to the geometry of the semitransparent photovoltaic device. We here demonstrate and evaluate this photovoltage loss in semi-transparent organic photovoltaic devices, compared with non-transparent solar cells of the same material. Semi-transparent solar cells in addition introduce photovoltage loss when formed by lamination. We document and analyze these effects for a number of polymer blends in the form of bulk heterojunctions.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2018. p. 60
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1974
National Category
Polymer Chemistry Polymer Technologies Materials Chemistry
Identifiers
urn:nbn:se:liu:diva-153616 (URN)10.3384/diss.diva-153616 (DOI)9789176851463 (ISBN)
Public defence
2019-01-18, Planck, Fysikhouset, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2019-01-04 Created: 2019-01-04 Last updated: 2019-01-04Bibliographically approved
Lin, Y., Zhao, F., Wu, Y., Chen, K., Xia, Y., Li, G., . . . Zhan, X. (2017). Mapping Polymer Donors toward High-Efficiency Fullerene Free Organic Solar Cells. Advanced Materials, 29(3), Article ID UNSP 1604155.
Open this publication in new window or tab >>Mapping Polymer Donors toward High-Efficiency Fullerene Free Organic Solar Cells
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2017 (English)In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 29, no 3, article id UNSP 1604155Article in journal (Refereed) Published
Abstract [en]

Five polymer donors with distinct chemical structures and different electronic properties are surveyed in a planar and narrow-bandgap fused-ring electron acceptor (IDIC)-based organic solar cells, which exhibit power conversion efficiencies of up to 11%.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2017
National Category
Materials Chemistry
Identifiers
urn:nbn:se:liu:diva-134981 (URN)10.1002/adma.201604155 (DOI)000392729800017 ()27862373 (PubMedID)
Note

Funding Agencies|973 Program [2013CB834702]; Ministry of Science and Technology of China [2016YFA0200700]; NSFC [91433114, 21504058, 21504066]; Scientific Research Project of Beijing Educational Committee [KM201610028006]; Office of Science, Office of Basic Energy Sciences of the U.S. Department of Energy [DE-AC02-05CH11231]

Available from: 2017-03-06 Created: 2017-03-06 Last updated: 2017-11-29
Xia, Y., Musumeci, C., Bergqvist, J., Ma, W., Gao, F., Tang, Z., . . . Wang, E. (2016). Inverted all-polymer solar cells based on a quinoxaline-thiophene/naphthalene-diimide polymer blend improved by annealing. Journal of Materials Chemistry A, 4(10), 3835-3843
Open this publication in new window or tab >>Inverted all-polymer solar cells based on a quinoxaline-thiophene/naphthalene-diimide polymer blend improved by annealing
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2016 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, no 10, p. 3835-3843Article in journal (Refereed) Published
Abstract [en]

We have investigated the effect of thermal annealing on the photovoltaic parameters of all-polymer solar cells based on a quinoxaline-thiophene donor polymer (TQ1) and a naphthalene diimide acceptor polymer (N2200). The annealed devices show a doubled power conversion efficiency compared to nonannealed devices, due to the higher short-circuit current (J(sc)) and fill factor (FF), but with a lower open circuit voltage (V-oc). On the basis of the morphology-mobility examination by several scanning force microscopy techniques, and by grazing-incidence wide-angle X-ray scattering, we conclude that better charge transport is achieved by higher order and better interconnected networks of the bulk heterojunction in the annealed active layers. The annealing improves charge transport and extends the conjugation length of the polymers, which do help in charge generation and meanwhile reduce recombination. Photoluminescence, electroluminescence, and light intensity dependence measurements reveal how this morphological change affects charge generation and recombination. As a result, the J(sc) and FF are significantly improved. However, the smaller band gap and the higher HOMO level of TQ1 upon annealing causes a lower V-oc. The blend of an amorphous polymer TQ1, and a semi-crystalline polymer N2200, can thus be modified by thermal annealing to double the power conversion efficiency.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2016
National Category
Biological Sciences
Identifiers
urn:nbn:se:liu:diva-127066 (URN)10.1039/c6ta00531d (DOI)000371967000030 ()
Note

Funding Agencies|Swedish Energy Agency; Swedish Research council, NSFC [21504006, 21534003]; Knut and Alice Wallenberg Foundation through a Wallenberg scholar grant; China Scholarship Council (CSC); graduate student short-term abroad research project of Jinan University; program for the Excellent Doctoral Dissertations of Guangdong Province [ybzzxm201114]; U.S. Department of Energy [DE-AC02-05CH11231]

Available from: 2016-04-13 Created: 2016-04-13 Last updated: 2019-01-04
Wang, C. F., Xu, X., Zhang, W., Bergqvist, J., Xia, Y., Meng, X., . . . Wang, E. (2016). Low Band Gap Polymer Solar Cells With Minimal Voltage Losses. ADVANCED ENERGY MATERIALS, 6(18), Article ID 1600148.
Open this publication in new window or tab >>Low Band Gap Polymer Solar Cells With Minimal Voltage Losses
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2016 (English)In: ADVANCED ENERGY MATERIALS, ISSN 1614-6832, Vol. 6, no 18, article id 1600148Article in journal (Refereed) Published
Abstract [en]

One of the factors limiting the performance of organic solar cells (OSCs) is their large energy losses (E-loss) in the conversion from photons to electrons, typically believed to be around 0.6 eV and often higher than those of inorganic solar cells. In this work, a novel low band gap polymer PIDTT-TID with a optical gap of 1.49 eV is synthesized and used as the donor combined with PC 71 BM in solar cells. These solar cells attain a good power conversion efficiency of 6.7% with a high open-circuit voltage of 1.0 V, leading to the E-loss as low as 0.49 eV. A systematic study indicates that the driving force in this donor and acceptor system is sufficient for charge generation with the low E-loss. This work pushes the minimal E-loss of OSCs down to 0.49 eV, approaching the values of some inorganic and hybrid solar cells. It indicates the potential for further enhancement of the performance of OSCs by improving their V-oc since the E-loss can be minimized.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2016
National Category
Energy Systems
Identifiers
urn:nbn:se:liu:diva-133010 (URN)10.1002/aenm.201600148 (DOI)000387132200002 ()
Note

Funding Agencies|Swedish Research Council; Swedish Research Council Formas; Swedish Energy Agency; Chalmers Area of Advance Energy and Materials Science; EU projects SUNFLOWER-"SUstainable Novel FLexible Organic Watts Efficiently Reliable" [287594]; Knut and Alice Wallenberg foundation; program for the Excellent Doctoral Dissertations of Guangdong Province [ybzzxm201114]; China Scholarship Council; National Natural Science Foundation of China [21504066, 21534003]; Office of Science, Office of Basic Energy Sciences of the U.S. Department of Energy [DE-AC02-05CH11231]

Available from: 2016-12-08 Created: 2016-12-07 Last updated: 2017-11-15
Bakulin, A. A., Xia, Y., Bakker, H. J., Inganäs, O. & Gao, F. (2016). Morphology, Temperature, and Field Dependence Separation in High-Efficiency Solar Cells Based on Polyquinoxaline Copolymer. The Journal of Physical Chemistry C, 120(8), 4219-4226
Open this publication in new window or tab >>Morphology, Temperature, and Field Dependence Separation in High-Efficiency Solar Cells Based on Polyquinoxaline Copolymer
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2016 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, no 8, p. 4219-4226Article in journal (Refereed) Published
Abstract [en]

Charge separation and recombination are key processes determining the performance of organic optoelectronic devices. Here we combine photoluminescence and photovoltaic characterization of organic solar cell devices with ultrafast multipulse photocurrent spectroscopy to investigate charge generation mechanisms in the organic photovoltaic devices based on a blend of an alternating polyquinoxaline copolymer with fullerene. The combined use of these techniques enables the determination of the contributions of geminate and bimolecular processes to the solar cell performance. We observe that charge separation is not a temperature-activated process in the studied materials. At the same time, the generation of free charges shows a dear external field and morphology dependence. This indicates that the critical step of charge separation involves the nonequilibrium state that is formed at early times after photoexcitation, when the polaronic localization is not yet complete. This work reveals new aspects of molecular level charge dynamics in the organic light-conversion systems.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2016
National Category
Biological Sciences
Identifiers
urn:nbn:se:liu:diva-126807 (URN)10.1021/acs.jpcc.5b10801 (DOI)000371562000007 ()
Note

Funding Agencies|Netherlands Organization for Scientific Research (NWO) through the "Stichting voor Fundamenteel Onderzoek der Materie" (FOM); VENI grant from NWO; Swedish Research Council (VR); European Commission Marie Sklodowska-Curie actions; Swedish Energy Agency; Knut and Alice Wallenberg foundation (KAW)

Available from: 2016-04-07 Created: 2016-04-05 Last updated: 2017-11-30
Li, Y., Liu, X., Wu, F.-P., Zhou, Y., Jiang, Z.-Q., Song, B., . . . Liao, L.-S. (2016). Non-fullerene acceptor with low energy loss and high external quantum efficiency: towards high performance polymer solar cells. Journal of Materials Chemistry A, 4(16), 5890-5897
Open this publication in new window or tab >>Non-fullerene acceptor with low energy loss and high external quantum efficiency: towards high performance polymer solar cells
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2016 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, no 16, p. 5890-5897Article in journal (Refereed) Published
Abstract [en]

A non-fullerene electron acceptor bearing a fused 10-heterocyclic ring (indacenodithiophenoindacenodithiophene) with a narrow band gap (similar to 1.5 eV) was designed and synthesized. It possesses excellent planarity and enhanced effective conjugation length compared to previously reported fused-ring electron acceptors. When this acceptor was paired with PTB7-Th and applied in polymer solar cells, a power conversion efficiency of 6.5% was achieved with a high open circuit voltage of 0.94 V. More significantly, an energy loss as low as 0.59 eV and an external quantum efficiency as high as 63% were obtained simultaneously.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2016
National Category
Biological Sciences
Identifiers
urn:nbn:se:liu:diva-128773 (URN)10.1039/c6ta00612d (DOI)000374790700016 ()
Note

Funding Agencies|National Natural Science Foundation of China [21504062, 21202114, 21204054, 51303118, 91333204]; Natural Science Foundation of Jiangsu Province [BK20130289]; China Postdoctoral Science Foundation Funded Project [2015M581853]; Jiangsu Province Postdoctoral Science Foundation Funded Project [1501024B]; Priority Academic Program Development of Jiangsu Higher Education Institutions; Programs Foundation of the Ministry of Education of China [20133201120008]; Beijing National Laboratory for Molecular Sciences [20140112]; State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials; CSC; Open Research Fund of State Key Lab of Silicon Materials (Zhejiang University); Knut and Alice Wallenberg foundation; Science Council, Sweden

Available from: 2016-05-30 Created: 2016-05-30 Last updated: 2017-11-30
George, Z., Xia, Y., Sharma, A., Lindqvist, C., Andersson, G., Inganäs, O., . . . Andersson, M. R. (2016). Two-in-one: cathode modification and improved solar cell blend stability through addition of modified fullerenes. Journal of Materials Chemistry A, 4(7), 2663-2669
Open this publication in new window or tab >>Two-in-one: cathode modification and improved solar cell blend stability through addition of modified fullerenes
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2016 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, no 7, p. 2663-2669Article in journal (Refereed) Published
Abstract [en]

The synthesis of dual purpose modified fullerenes with pyridine-as well as amine-functional groups is reported. Addition of these fullerenes to a polymer : fullerene bulk-heterojunction blend based on a thiophene-quinoxaline donor polymer is found to modify the active layer/cathode interface of inverted solar cells (glass/ITO/active layer/MoO3/Al). In particular the open-circuit voltage of devices is increased from 0.1 V to about 0.7 V, which results in a drastic rise in photovoltaic performance with a power conversion efficiency of up to 3%. At the same time, presence of the functionalised fullerene additives prevents the detrimental formation of micrometre-sized fullerene crystals upon annealing at 140 degrees C. As a result, the device performance is retained, which promises significantly increased thermal stability of the bulk-heterojunction blend nanostructure.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2016
National Category
Biological Sciences
Identifiers
urn:nbn:se:liu:diva-125692 (URN)10.1039/c5ta06420a (DOI)000369665800033 ()
Note

Funding Agencies|Swedish Energy Agency; Swedish Research Council; Knut and Alice Wallenberg Foundation; Chinese Scholarship Council (CSC); South Australian government

Available from: 2016-03-01 Created: 2016-02-29 Last updated: 2017-11-30
Peng, Z., Xia, Y., Gao, F., Xiong, K., Hu, Z., Ian James, D., . . . Hou, L. (2015). A dual ternary system for highly efficient ITO-free inverted polymer solar cells. Journal of Materials Chemistry A, 3(36), 18365-18371
Open this publication in new window or tab >>A dual ternary system for highly efficient ITO-free inverted polymer solar cells
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2015 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, no 36, p. 18365-18371Article in journal (Refereed) Published
Abstract [en]

In this study, it has been found that a very fine nanostructure can be realized by mixing 1-chloronaphthalene (CN) - a high-boiling solvent into a binary chlorobenzene (CB) : 1,8-diiodooctane (DIO) solvent mixture to form a ternary solvent system. An improvement in energy level alignment is also obtained by doping ICBA into a binary PTB7 : PCBM[70] blend, whereby the ternary solute system provides a new pathway for charge transfer from PTB7 to the PCBM[ 70] : ICBA alloy. This is confirmed by imaging the surface morphology of the active layer using AFM and TEM, monitoring the transient film formation process and measuring the charge transfer states with Fourier transform photocurrent spectroscopy. An encouraging PCE of 7.65% is achieved from the dual ternary system, which is the highest value ever reported for an ITO-free inverted polymer solar cell with a PEDOT:PSS layer as the top semitransparent electrode - a system which is compatible with low-cost large-area roll-to-roll manufacturing.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2015
National Category
Biological Sciences
Identifiers
urn:nbn:se:liu:diva-121444 (URN)10.1039/c5ta03831f (DOI)000360490600005 ()
Note

Funding Agencies|NSFC Project [11204106, 61274062, 21225418]; Open Fund of State Key Laboratory of Luminescent Materials and Devices (South China University of Technology) [2012-skllmd-10, 2013-skllmd-06, 2015-skllmd-02]; Fundamental Research Fund for Central Universities; Swedish Research Council (VR); Excellent Doctoral Dissertations of Guangdong Province [ybzzxm201114]

Available from: 2015-09-18 Created: 2015-09-18 Last updated: 2017-12-04
Tao, Q., Xia, Y., Xu, X., Hedstrom, S., Backe, O., James, D. I., . . . Wang, E. (2015). D-A(1)-D-A(2) Copolymers with Extended Donor Segments for Efficient Polymer Solar Cells. Macromolecules, 48(4), 1009-1016
Open this publication in new window or tab >>D-A(1)-D-A(2) Copolymers with Extended Donor Segments for Efficient Polymer Solar Cells
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2015 (English)In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 48, no 4, p. 1009-1016Article in journal (Refereed) Published
Abstract [en]

Typically a donor-acceptor (D-A) design strategy is used for engineering the bandgap of polymers for solar cells. However, in this work, a series of alternating D-A(1-)D-A(2) copolymers PnTQTI(F) were synthesized and characterized with oligothiophenes (nT, n = 1, 2, 3) as the donor and two electron-deficient moieties, quinoxaline and isoindigo, as the acceptors in the repeating unit. We have studied the influence of the donor segments with different numbers of thiophene units and the effect of the addition of fluorine to the quinoxaline unit of the D-A(1)-D-A(2) polymers. The photophysical, electrochemical, and photovoltaic properties of the polymers were examined via a range of techniques and related to theoretical simulations. On increasing the length of the donor thiophene units, broader absorption spectra were observed in addition to a sequential increase in HOMO levels, while the LUMO levels displayed very small variations. The addition of fluorine to the quinoxaline unit not only decreased the HOMO levels of the resulting polymers but also enhanced the absorption coefficients. A superior photovoltaic performance was observed for the P3TQTI-F-based device with a power conversion efficiency (PCE) of 7.0%, which is the highest efficiency for alternating D-A(1)-D-A(2) polymers reported to date. The structureproperty correlations of the PnTQTI(F) polymers demonstrate that varying of the length of the donor segments is a valuable method for designing high-performance D-A(1)-D-A(2) copolymers and highlight the promising nature of D-A(1)-D-A(2) copolymers for efficient bulk-heterojunction solar cells.

Place, publisher, year, edition, pages
American Chemical Society, 2015
National Category
Biological Sciences
Identifiers
urn:nbn:se:liu:diva-116834 (URN)10.1021/ma502186g (DOI)000350193900015 ()
Note

Funding Agencies|Swedish Research Council; Swedish Energy Agency; EU [FP7-ICT-2011-7, 287594]; National Natural Science Foundation of China [21172187]

Available from: 2015-04-07 Created: 2015-04-07 Last updated: 2017-12-04
Peng, Z., Zhang, Y., Xia, Y., Xiong, K., Cai, C., Xia, L., . . . Hou, L. (2015). One-step coating inverted polymer solar cells using a conjugated polymer as an electron extraction additive. Journal of Materials Chemistry A, 3(41), 20500-20507
Open this publication in new window or tab >>One-step coating inverted polymer solar cells using a conjugated polymer as an electron extraction additive
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2015 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, no 41, p. 20500-20507Article in journal (Refereed) Published
Abstract [en]

We report a facile technique of blending a conjugated polymer thieno[3,4-b]thiophene/benzodithiophene (PTB7):[6,6]-phenyl-C71-butyric acid methyl ester (PCBM[70]) active materials with a conjugated interfacial modification polymer poly[(9,9-bis(3-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFN) to simplify the coating process and improve the bulk heterojunction (BHJ) polymer solar cell (PSC) performance. The reason for and result of PFN self-organization via a spontaneous vertical delamination onto the ITO surface were investigated by charge transfer state, optical modelling based on transfer matrix formalism, surface energy measurement, scanning Kelvin probe force microscopy and impedance spectroscopy analysis in conjunction with atomic force microscopy and scanning electron microscopy. The relaxed charge transfer state demonstrates that PFN doping has a negligible impact on the donor: acceptor heterojunction interface. The optical simulation of device structures indicates that doping PFN into a BHJ has nearly no influence on the photon absorption profile of the active layer. Very encouraging device performance was achieved in the one-step coating PFN: BHJ PSC with ITO as the cathode, which is comparable to that of the two-step coating PSC. Moreover, for ITO-free inverted PSCs with PEDOT:PSS as the incident light top-electrode, decent device performance can also be obtained, demonstrating the remarkable universality through this facile strategy.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2015
National Category
Biological Sciences
Identifiers
urn:nbn:se:liu:diva-122671 (URN)10.1039/c5ta06009e (DOI)000363145500009 ()
Note

Funding Agencies|NSFC Project [11204106, 61274062]; State Key Laboratory of Luminescent Materials and Devices (South China University of Technology) [2012-skllmd-10]; Fundamental Research Funds for the Central Universities

Available from: 2015-11-16 Created: 2015-11-13 Last updated: 2017-12-01
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