@article{UchidaBinetAroraetal.2018,
  author    = {Uchida, Ryusuke and Binet, Silvia and Arora, Neha and Jacopin, Gwenole and Alotaibi, Mohammad Hayal and Taubert, Andreas and Zakeeruddin, Shaik Mohammed and Dar, M. Ibrahim and Graetzel, Michael},
  title     = {Insights about the Absence of Rb Cation from the 3D Perovskite Lattice},
  series = {Small},
  volume    = {14},
  journal   = {Small},
  number    = {36},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1613-6810},
  doi       = {10.1002/smll.201802033},
  pages     = {7},
  year      = {2018},
  abstract  = {Efficiencies >20\% are obtained from the perovskite solar cells (PSCs) employing Cs+ and Rb+ based perovskite compositions; therefore, it is important to understand the effect of these inorganic cations specifically Rb+ on the properties of perovskite structures. Here the influence of Cs+ and Rb+ is elucidated on the structural, morphological, and photophysical properties of perovskite structures and the photovoltaic performances of resulting PSCs. Structural, photoluminescence (PL), and external quantum efficiency studies establish the incorporation of Cs+ (x < 10\%) but amply rule out the possibility of Rb-incorporation into the MAPbI(3) (MA = CH3NH3+) lattice. Moreover, morphological studies and time-resolved PL show that both Cs+ and Rb+ detrimentally affect the surface coverage of MAPbI(3) layers and charge-carrier dynamics, respectively, by influencing nucleation density and by inducing nonradiative recombination. In addition, differential scanning calorimetry shows that the transition from orthorhombic to tetragonal phase occurring around 160 K requires more thermal energy for the Cs-containing MAPbI(3) systems compared to the pristine MAPbI(3). Investigation including mixed halide (I/Br) and mixed cation A-cation based compositions further confirms the absence of Rb+ from the 3D-perovskite lattice. The fundamental insights gained through this work will be of great significance to further understand highly promising perovskite compositions.},
  language  = {en}
}
@misc{LehmannBinetFranzetal.2018,
  author    = {Lehmann, Frederike and Binet, Silvia and Franz, Alexandra and Taubert, Andreas and Schorr, Susan},
  title     = {Cation and anion substitutions in hybrid perovskites},
  series = {7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC \& 34th EU PVSEC)},
  journal   = {7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC \& 34th EU PVSEC)},
  publisher = {IEEE},
  address   = {New York},
  isbn      = {978-1-5386-8529-7},
  issn      = {2159-2330},
  doi       = {10.1109/PVSC.2018.8547645},
  pages     = {1555 -- 1558},
  year      = {2018},
  abstract  = {Organic or inorganic (A) metal (M) halide (X) perovskites (AMX(3)) are semiconductor materials setting the basis for the development of highly efficient, low-cost and multijunction solar energy conversion devices. The best efficiencies nowadays are obtained with mixed compositions containing methylammonium, formamidinium, Cs and Rb as well as iodine, bromine and chlorine as anions. The understanding of fundamental properties such as crystal structure and its effect on the band gap, as well as their phase stability is essential. In this systematic study X-ray diffraction and photoluminescense spectroscopy were applied to evaluate structural and optoelectronic properties of hybrid perovskites with mixed compositions.},
  language  = {en}
}