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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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