@article{PenaCamargoThiesbrummelHempeletal.2022,
  author    = {Pena-Camargo, Francisco and Thiesbrummel, Jarla and Hempel, Hannes and Musiienko, Artem and Le Corre, Vincent M. and Diekmann, Jonas and Warby, Jonathan and Unold, Thomas and Lang, Felix and Neher, Dieter and Stolterfoht, Martin},
  title     = {Revealing the doping density in perovskite solar cells and its impact on device performance},
  series = {Applied physics reviews},
  volume    = {9},
  journal   = {Applied physics reviews},
  number    = {2},
  publisher = {AIP Publishing},
  address   = {Melville},
  issn      = {1931-9401},
  doi       = {10.1063/5.0085286},
  pages     = {11},
  year      = {2022},
  abstract  = {Traditional inorganic semiconductors can be electronically doped with high precision. Conversely, there is still conjecture regarding the assessment of the electronic doping density in metal-halide perovskites, not to mention of a control thereof. This paper presents a multifaceted approach to determine the electronic doping density for a range of different lead-halide perovskite systems. Optical and electrical characterization techniques, comprising intensity-dependent and transient photoluminescence, AC Hall effect, transfer-length-methods, and charge extraction measurements were instrumental in quantifying an upper limit for the doping density. The obtained values are subsequently compared to the electrode charge per cell volume under short-circuit conditions ( CUbi/eV), which amounts to roughly 10(16) cm(-3). This figure of merit represents the critical limit below which doping-induced charges do not influence the device performance. The experimental results consistently demonstrate that the doping density is below this critical threshold 10(12) cm(-3), which means << CUbi / e V) for all common lead-based metal-halide perovskites. Nevertheless, although the density of doping-induced charges is too low to redistribute the built-in voltage in the perovskite active layer, mobile ions are present in sufficient quantities to create space-charge-regions in the active layer, reminiscent of doped pn-junctions. These results are well supported by drift-diffusion simulations, which confirm that the device performance is not affected by such low doping densities.},
  language  = {en}
}
@article{LeCorreDiekmannPenaCamargoetal.2022,
  author    = {Le Corre, Vincent M. and Diekmann, Jonas and Pe{\~n}a-Camargo, Francisco and Thiesbrummel, Jarla and Tokmoldin, Nurlan and Gutierrez-Partida, Emilio and Peters, Karol Pawel and Perdig{\´o}n-Toro, Lorena and Futscher, Moritz H. and Lang, Felix and Warby, Jonathan and Snaith, Henry J. and Neher, Dieter and Stolterfoht, Martin},
  title     = {Quantification of efficiency losses due to mobile ions in Perovskite solar cells via fast hysteresis measurements},
  series = {Solar RRL},
  volume    = {6},
  journal   = {Solar RRL},
  number    = {4},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {2367-198X},
  doi       = {10.1002/solr.202100772},
  pages     = {10},
  year      = {2022},
  abstract  = {Perovskite semiconductors differ from most inorganic and organic semiconductors due to the presence of mobile ions in the material. Although the phenomenon is intensively investigated, important questions such as the exact impact of the mobile ions on the steady-state power conversion efficiency (PCE) and stability remain. Herein, a simple method is proposed to estimate the efficiency loss due to mobile ions via "fast-hysteresis" measurements by preventing the perturbation of mobile ions out of their equilibrium position at fast scan speeds (approximate to 1000 V s(-1)). The "ion-free" PCE is between 1\% and 3\% higher than the steady-state PCE, demonstrating the importance of ion-induced losses, even in cells with low levels of hysteresis at typical scan speeds (approximate to 100mv s(-1)). The hysteresis over many orders of magnitude in scan speed provides important information on the effective ion diffusion constant from the peak hysteresis position. The fast-hysteresis measurements are corroborated by transient charge extraction and capacitance measurements and numerical simulations, which confirm the experimental findings and provide important insights into the charge carrier dynamics. The proposed method to quantify PCE losses due to field screening induced by mobile ions clarifies several important experimental observations and opens up a large range of future experiments.},
  language  = {en}
}