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Author Ben Dkhil, S.; Pfannmöller, M.; Saba, M.I.; Gaceur, M.; Heidari, H.; Videlot-Ackermann, C.; Margeat, O.; Guerrero, A.; Bisquert, J.; Garcia-Belmonte, G.; Mattoni, A.; Bals, S.; Ackermann, J. pdf  doi
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  Title Toward high-temperature stability of PTB7-based bulk heterojunction solar cells : impact of fullerene size and solvent additive Type A1 Journal article
  Year (down) 2017 Publication Laser physics review Abbreviated Journal Adv Energy Mater  
  Volume 7 Issue 7 Pages 1601486  
  Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)  
  Abstract The use of fullerene as acceptor limits the thermal stability of organic solar cells at high temperatures as their diffusion inside the donor leads to phase separation via Ostwald ripening. Here it is reported that fullerene diffusion is fully suppressed at temperatures up to 140 degrees C in bulk heterojunctions based on the benzodithiophene-based polymer (the poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b: 4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl) carbonyl]thieno[3,4-b]thiophenediyl]], (PTB7) in combination with the fullerene derivative [6,6]-phenyl-C71-butyric acid methyl ester (PC70BM). The blend stability is found independently of the presence of diiodooctane (DIO) used to optimize nanostructuration and in contrast to PTB7 blends using the smaller fullerene derivative PC70BM. The unprecedented thermal stability of PTB7: PC70BM layers is addressed to local minima in the mixing enthalpy of the blend forming stable phases that inhibit fullerene diffusion. Importantly, although the nanoscale morphology of DIO processed blends is thermally stable, corresponding devices show strong performance losses under thermal stress. Only by the use of a high temperature annealing step removing residual DIO from the device, remarkably stable high efficiency solar cells with performance losses less than 10% after a continuous annealing at 140 degrees C over 3 days are obtained. These results pave the way toward high temperature stable polymer solar cells using fullerene acceptors.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Place of publication unknown Editor  
  Language Wos 000396328500009 Publication Date 2016-11-07  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1614-6832; ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 16.721 Times cited 27 Open Access Not_Open_Access  
  Notes ; The authors acknowledge financial support by the French Fond Unique Interministeriel (FUI) under the project “SFUMATO” (grant number: F1110019V/ 201308815) as well as by the European Commission under the Project “SUNFLOWER” (FP7-ICT-2011-7, grant number: 287594). Generalitat Valenciana (ISIC/2012/008 Institute of Nanotechnologies for Clean Energies) is also acknowledged for providing financial support. The authors further acknowledge financial support via ERC Starting Grant Colouratoms (335078). ; Approved Most recent IF: 16.721  
  Call Number UA @ lucian @ c:irua:141991UA @ admin @ c:irua:141991 Serial 4697  
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Author Guerrero, A.; Heidari, H.; Ripolles, T.S.; Kovalenko, A.; Pfannmöller, M.; Bals, S.; Kauffmann, L.-D.; Bisquert, J.; Garcia-Belmonte, G. pdf  url
doi  openurl
  Title Shelf life degradation of bulk heterojunction solar cells : intrinsic evolution of charge transfer complex Type A1 Journal article
  Year (down) 2015 Publication Laser physics review Abbreviated Journal Adv Energy Mater  
  Volume 5 Issue 5 Pages 1401997  
  Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)  
  Abstract Achievement of long-term stability of organic photovoltaics is currently one of the major topics for this technology to reach maturity. Most of the techniques used to reveal degradation pathways are destructive and/or do not allow for real-time measurements in operating devices. Here, three different, nondestructive techniques able to provide real-time information, namely, film absorbance, capacitance-voltage (C-V), and impedance spectroscopy (IS), are combined over a period of 1 year using non-accelerated intrinsic degradation conditions. It is discerned between chemical modifications in the active layer, physical processes taking place in the bulk of the blend from those at the active layer/contact interfaces. In particular, it is observed that during the ageing experiment, the main source for device performance degradation is the formation of donor-acceptor charge-transfer complex (P3HT(center dot+)-PCBM center dot-) that acts as an exciton quencher. Generation of these radical species diminishes photocurrent and reduces open-circuit voltage by the creation of electronic defect states. Conclusions extracted from absorption, C-V, and IS measurements will be further supported by a range of other techniques such as atomic force microscopy, X-ray diffraction, and dark-field imaging of scanning transmission electron microscopy on ultrathin cross-sections.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication S.l. Editor  
  Language Wos 000352708600013 Publication Date 2014-12-12  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1614-6832; ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 16.721 Times cited 30 Open Access OpenAccess  
  Notes 287594 Sunflower; 335078 Colouratom; ECAS_Sara; (ROMEO:yellow; preprint:; postprint:restricted ; pdfversion:cannot); Approved Most recent IF: 16.721; 2015 IF: 16.146  
  Call Number c:irua:126000 Serial 2994  
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Author Guerrero, A.; Pfannmöller, M.; Kovalenko, A.; Ripolles, T.S.; Heidari, H.; Bals, S.; Kaufmann, L.-D.; Bisquert, J.; Garcia-Belmonte, G. pdf  url
doi  openurl
  Title Nanoscale mapping by electron energy-loss spectroscopy reveals evolution of organic solar cell contact selectivity Type A1 Journal article
  Year (down) 2015 Publication Organic electronics: physics, materials, applications Abbreviated Journal Org Electron  
  Volume 16 Issue 16 Pages 227-233  
  Keywords A1 Journal article; Electron microscopy for materials research (EMAT)  
  Abstract Organic photovoltaic (OPV) devices are on the verge of commercialization being long-term stability a key challenge. Morphology evolution during lifetime has been suggested to be one of the main pathways accounting for performance degradation. There is however a lack of certainty on how specifically the morphology evolution relates to individual electrical parameters on operating devices. In this work a case study is created based on a thermodynamically unstable organic active layer which is monitored over a period of one year under non-accelerated degradation conditions. The morphology evolution is revealed by compositional analysis of ultrathin cross-sections using nanoscale imaging in scanning transmission electron microscopy (STEM) coupled with electron energy-loss spectroscopy (EELS). Additionally, devices are electrically monitored in real-time using the non-destructive electrical techniques capacitance-voltage (C-V) and Impedance Spectroscopy (IS). By comparison of imaging and electrical techniques the relationship between nanoscale morphology and individual electrical parameters of device operation can be conclusively discerned. It is ultimately observed how the change in the cathode contact properties occurring after the migration of fullerene molecules explains the improvement in the overall device performance. (C) 2014 Elsevier B.V. All rights reserved.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication London Editor  
  Language Wos 000345649500029 Publication Date 2014-11-17  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1566-1199; ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 3.399 Times cited 24 Open Access OpenAccess  
  Notes 287594 Sunflower; 335078 Colouratom; ECAS_Sara; (ROMEO:green; preprint:; postprint:can ; pdfversion:cannot); Approved Most recent IF: 3.399; 2015 IF: 3.827  
  Call Number c:irua:122169 Serial 2267  
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