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@PHDTHESIS{Mock:844739,
      author       = {Mock, Jan Peter},
      title        = {{F}ehlstellendotierung von {E}isenoxid- und
                      {B}ismutsulfid-{N}anopartikeln},
      volume       = {415},
      school       = {RWTH Aachen},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2018-02119},
      isbn         = {978-3-95806-309-9},
      series       = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
                      Umwelt / Energy $\&$ Environment},
      pages        = {183 S.},
      year         = {2018},
      note         = {RWTH Aachen, Diss., 2018},
      abstract     = {In this work semiconducting iron oxide and bismuth sulde
                      nanoparticles are characterized and modied, which should be
                      applied by an innovative solar cell concept as active
                      absorber materials, for example in combination with organic
                      polymers. The advantage of this concept is that the
                      manufacturing process and the optimization of the absorber
                      materials can be separated from the module production. The
                      aim of the present work was to improve the electrical
                      transport properties of hematite ($\alpha$-Fe$_{2}$O$_{3}$)
                      and bismuth sulfide (Bi$_{2}$S$_{3}$) as nanoparticle
                      layers. The focus was on the concept of doping via native
                      point defects. It has been shown that the introduction of
                      defects and the associated doping of the semiconducting
                      nanoparticle layers is a promising approach to tune their
                      electrical transport properties. It was demonstrated for the
                      first time how the electrical conductivity of hematite can
                      be continuously increased by five orders of magnitude
                      through a stepwise temperature treatment (300 - 620 K). This
                      simple method can be applied to hematite in the form of
                      nanoparticle layers as well as in the form of thin layers.
                      By measuring the thermoelectric power, an increase in the
                      charge carrier concentration of about three orders of
                      magnitude was determined. This was attributed to an
                      increasing formation of doping oxygen vacancies and thus to
                      an increasing deviation of the stoichiometric composition of
                      hematite ($\alpha$-Fe$_{2}$O$_{3-x}$ with increasing x).
                      Furthermore, it has been shown that the mobility of the
                      charge carriers is also increased as a result of doping by
                      oxygen vacancies. For the first time, the activation energy
                      of mobility of hematite nanoparticle layers was determined.
                      In the case of nanoparticle layers, a limiting potential
                      barrier between the respective nanoparticles was identified
                      and a picture is proposed for this potential barrier. The
                      height of the potential barrier of the fundamental transport
                      mechanism in the model of the small polaron hopping could be
                      below 0.1 eV. These results are a valuable supplement to the
                      understanding of the charge carrier transport mechanism in
                      hematite. Furthermore, it has been shown that the phase
                      transformation of hematite into magnetite (Fe$_{3}$O$_{4}$)
                      occurs at a vacuum base pressure below 10$^{-6}$ mbar in a
                      temperature range between 597 K and 620 K. This result is in
                      contradiction with the previous stability diagram of iron
                      oxide, in which this phase transformation is expected at a
                      temperature of about 1000 K. In this respect, the results of
                      this work call into question the previous understanding of
                      the temperature of the phase transformation of hematite into
                      magnetite. The native defect doping developed for hematite
                      was transferred to bismuth sulfide nanoparticle layers. In
                      this case, in addition to the introduction of doping sulfur
                      defects, [...]},
      cin          = {IEK-5},
      cid          = {I:(DE-Juel1)IEK-5-20101013},
      pnm          = {121 - Solar cells of the next generation (POF3-121)},
      pid          = {G:(DE-HGF)POF3-121},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      url          = {https://juser.fz-juelich.de/record/844739},
}