@article{LangeReiterKniepertetal.2015,
  author    = {Lange, Ilja and Reiter, Sina and Kniepert, Juliane and Piersimoni, Fortunato and Paetzel, Michael and Hildebrandt, Jana and Brenner, Thomas J. K. and Hecht, Stefan and Neher, Dieter},
  title     = {Zinc oxide modified with benzylphosphonic acids as transparent electrodes in regular and inverted organic solar cell structures},
  series = {Applied physics letters},
  volume    = {106},
  journal   = {Applied physics letters},
  number    = {11},
  publisher = {American Institute of Physics},
  address   = {Melville},
  issn      = {0003-6951},
  doi       = {10.1063/1.4916182},
  pages     = {5},
  year      = {2015},
  abstract  = {An approach is presented to modify the work function of solution-processed sol-gel derived zinc oxide (ZnO) over an exceptionally wide range of more than 2.3 eV. This approach relies on the formation of dense and homogeneous self-assembled monolayers based on phosphonic acids with different dipole moments. This allows us to apply ZnO as charge selective bottom electrodes in either regular or inverted solar cell structures, using poly(3-hexylthiophene): phenyl-C71-butyric acid methyl ester as the active layer. These devices compete with or even surpass the performance of the reference on indium tin oxide/poly(3,4-ethylenedioxythiophene) polystyrene sulfonate. Our findings highlight the potential of properly modified ZnO as electron or hole extracting electrodes in hybrid optoelectronic devices. (C) 2015 AIP Publishing LLC.},
  language  = {en}
}
@article{LangeReiterPaetzeletal.2014,
  author    = {Lange, Ilja and Reiter, Sina and Paetzel, Michael and Zykov, Anton and Nefedov, Alexei and Hildebrandt, Jana and Hecht, Stefan and Kowarik, Stefan and Woell, Christof and Heimel, Georg and Neher, Dieter},
  title     = {Tuning the work function of polar zinc oxide surfaces using modified phosphonic acid self-assembled monolayers},
  series = {Advanced functional materials},
  volume    = {24},
  journal   = {Advanced functional materials},
  number    = {44},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1616-301X},
  doi       = {10.1002/adfm.201401493},
  pages     = {7014 -- 7024},
  year      = {2014},
  abstract  = {Zinc oxide (ZnO) is regarded as a promising alternative material for transparent conductive electrodes in optoelectronic devices. However, ZnO suffers from poor chemical stability. ZnO also has a moderate work function (WF), which results in substantial charge injection barriers into common (organic) semiconductors that constitute the active layer in a device. Controlling and tuning the ZnO WF is therefore necessary but challenging. Here, a variety of phosphonic acid based self-assembled monolayers (SAMs) deposited on ZnO surfaces are investigated. It is demonstrated that they allow the tuning the WF over a wide range of more than 1.5 eV, thus enabling the use of ZnO as both the hole-injecting and electron-injecting contact. The modified ZnO surfaces are characterized using a number of complementary techniques, demonstrating that the preparation protocol yields dense, well-defined molecular monolayers.},
  language  = {en}
}