@article{HempelSavenjieStolterfohtetal.2022,
  author    = {Hempel, Hannes and Savenjie, Tom J. and Stolterfoht, Martin and Neu, Jens and Failla, Michele and Paingad, Vaisakh C. and Kužel, Petr and Heilweil, Edwin J. and Spies, Jacob A. and Schleuning, Markus and Zhao, Jiashang and Friedrich, Dennis and Schwarzburg, Klaus and Siebbeles, Laurens D. A. and D{\"o}rflinger, Patrick and Dyakonov, Vladimir and Katoh, Ryuzi and Hong, Min Ji and Labram, John G. and Monti, Maurizio and Butler-Caddle, Edward and Lloyd-Hughes, James and Taheri, Mohammad M. and Baxter, Jason B. and Magnanelli, Timothy J. and Luo, Simon and Cardon, Joseph M. and Ardo, Shane and Unold, Thomas},
  title     = {Predicting solar cell performance from terahertz and microwave spectroscopy},
  series = {Advanced energy materials},
  volume    = {12},
  journal   = {Advanced energy materials},
  number    = {13},
  publisher = {Wiley},
  address   = {Weinheim},
  issn      = {1614-6832},
  doi       = {10.1002/aenm.202102776},
  pages     = {16},
  year      = {2022},
  abstract  = {Mobilities and lifetimes of photogenerated charge carriers are core properties of photovoltaic materials and can both be characterized by contactless terahertz or microwave measurements. Here, the expertise from fifteen laboratories is combined to quantitatively model the current-voltage characteristics of a solar cell from such measurements. To this end, the impact of measurement conditions, alternate interpretations, and experimental inter-laboratory variations are discussed using a (Cs,FA,MA)Pb(I,Br)(3) halide perovskite thin-film as a case study. At 1 sun equivalent excitation, neither transport nor recombination is significantly affected by exciton formation or trapping. Terahertz, microwave, and photoluminescence transients for the neat material yield consistent effective lifetimes implying a resistance-free JV-curve with a potential power conversion efficiency of 24.6 \%. For grainsizes above approximate to 20 nm, intra-grain charge transport is characterized by terahertz sum mobilities of approximate to 32 cm(2) V-1 s(-1). Drift-diffusion simulations indicate that these intra-grain mobilities can slightly reduce the fill factor of perovskite solar cells to 0.82, in accordance with the best-realized devices in the literature. Beyond perovskites, this work can guide a highly predictive characterization of any emerging semiconductor for photovoltaic or photoelectrochemical energy conversion. A best practice for the interpretation of terahertz and microwave measurements on photovoltaic materials is presented.},
  language  = {en}
}
@article{ShiEijtSandeepetal.2016,
  author    = {Shi, Wenqin and Eijt, Stephan W. H. and Sandeep, Chandramathi Sukumaran Suchand and Siebbeles, Laurens D. A. and Houtepen, Arjan J. and Kinge, Sachin and Bruck, Ekkes and Barbiellini, Bernardo and Bansil, Arun},
  title     = {Ligand-surface interactions and surface oxidation of colloidal PbSe quantum dots revealed by thin-film positron annihilation methods},
  series = {Applied physics letters},
  volume    = {108},
  journal   = {Applied physics letters},
  publisher = {American Institute of Physics},
  address   = {Melville},
  issn      = {0003-6951},
  doi       = {10.1063/1.4942609},
  pages     = {213 -- 230},
  year      = {2016},
  abstract  = {Positron Two Dimensional Angular Correlation of Annihilation Radiation (2D-ACAR) measurements reveal modifications of the electronic structure and composition at the surfaces of PbSe quantum dots (QDs), deposited as thin films, produced by various ligands containing either oxygen or nitrogen atoms. In particular, the 2D--ACAR measurements on thin films of colloidal PbSe QDs capped with oleic acid ligands yield an increased intensity in the electron momentum density (EMD) at high momenta compared to PbSe quantum dots capped with oleylamine. Moreover, the EMD of PbSe QDs is strongly affected by the small ethylenediamine ligands, since these molecules lead to small distances between QDs and favor neck formation between near neighbor QDs, inducing electronic coupling between neighboring QDs. The high sensitivity to the presence of oxygen atoms at the surface can be also exploited to monitor the surface oxidation of PbSe QDs upon exposure to air. Our study clearly demonstrates that positron annihilation spectroscopy applied to thin films can probe surface transformations of colloidal semiconductor QDs embedded in functional layers. (C) 2016 AIP Publishing LLC.},
  language  = {en}
}