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@INPROCEEDINGS{Urbain:200801,
      author       = {Urbain, Felix and Smirnov, Vladimir and Becker, Jan Philipp
                      and Lambertz, Andreas and Rau, Uwe and Finger, Friedhelm},
      title        = {{E}fficient multijunction thin film silicon solar cells
                      with open-circuit voltages up to 2.8 {V} for the application
                      in photoelectrochemical energy storage devices},
      reportid     = {FZJ-2015-03194},
      year         = {2015},
      abstract     = {We report on the development of multijunction solar cells
                      for the integration in photoelectrochemical devices for
                      hydrogen production. Hydrogen, as a storable chemical fuel,
                      can be generated through photoelectrolysis of water, a
                      chemical reaction which requires potentials, i.e.
                      photovoltages over 1.8V to run autonomously. The exact
                      voltage needed varies with the used catalysts. The
                      photocurrent at the respective required voltage determines
                      the solar-to-hydrogen device efficiency. It is therefore
                      important to develop solar cells which can cover up a wide
                      voltage (VOC and VMPP) range in combination with high
                      photocurrents. This high photovoltage/high photocurrent
                      tradeoff can be solved by multijunction solar cells made of
                      amorphous (a-Si:H) and microcrystalline (μc-Si:H)
                      silicon.We developed a-Si:H/a Si:H tandem, a Si:H/µc
                      Si:H/µc Si:H and a Si:H/a Si:H/µc Si:H triple, and a
                      Si:H/a Si:H/µc Si:H/µc Si:H quadruple junction solar
                      cells. The solar cells were optimized in terms of
                      photovoltage and photocurrent by varying the process
                      parameters and thickness of the intrinsic absorber layers
                      and by integrating microcrystalline silicon oxide as
                      intermediate reflecting layers to adjust the photocurrents
                      of the individual subcells. It was found that the electronic
                      properties of the individual series-connected subcells can
                      be adjusted to systematically tune the VOC between 1.9 V and
                      2.8 V and we achieved PV efficiencies over $11.5\%$ for
                      tandem and over $13.5\%$ for triple and quadruple cells.},
      month         = {May},
      date          = {2015-05-11},
      organization  = {EMRS Spring Conference, Lille
                       (France), 11 May 2015 - 15 May 2015},
      subtyp        = {Other},
      cin          = {IEK-5},
      cid          = {I:(DE-Juel1)IEK-5-20101013},
      pnm          = {126 - Solar Fuels (POF3-126) / 121 - Solar cells of the
                      next generation (POF3-121) / HITEC - Helmholtz
                      Interdisciplinary Doctoral Training in Energy and Climate
                      Research (HITEC) (HITEC-20170406)},
      pid          = {G:(DE-HGF)POF3-126 / G:(DE-HGF)POF3-121 /
                      G:(DE-Juel1)HITEC-20170406},
      typ          = {PUB:(DE-HGF)6},
      url          = {https://juser.fz-juelich.de/record/200801},
}