1 Deep Levels and Mixed Conductivity in Organometallic Halide Perovskites Artem Musiienko 1* , Pavel Moravec 1 , Roman Grill 1 , Petr Praus 1 , Igor Vasylchenko 1 , Jakub Pekarek 1 , Jeremy Tisdale 2 , Katarina Ridzonova 1 , Eduard Belas 1 , Lucie Abelová 3,4 , Bin Hu 2 , Eric Lukosi 5 , Mahshid Ahmadi 2* 1 Institute of Physics, Charles University, Prague, 121 16, Czech Republic 2 Joint Institute for Advanced Materials, Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA 3 Institute of Physics, Academy of Sciences of the Czech Republic, Prague, Czech Republic. 4 Electrical Engineering, Czech Technical University in Prague, Prague, Czech Republic 5 Joint Institute for Advanced Materials, Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996, USA *Corresponding author e-mails: M. Ahmadi: mahmadi3@utk.edu, A. Musiienko: musienko.art@gmail.com Abstract: Understanding the type, formation energy and capture cross section of defects is one of the challenges in the field of organometallic halide perovskite (OMHP) devices. Currently, such understanding is limited, restricting the power conversion efficiencies of OMHPs solar cells from reaching their Shockley–Queisser limit. In more matured semiconductors like Si, the knowledge of defects was one of the major factor in successful technological implementation. This knowledge and its control can make a paradigm in development of OMHP devices. Here, we report on deep level (DL) defects and their effect on free charge transport properties of single crystalline methylammonium lead bromide perovskite (MAPbBr3). In order to determine DL activation energy and capture cross section we used photo-Hall effect spectroscopy (PHES) with enhanced illumination in both steady-state and dynamic regimes. This method has shown to be convenient due to the direct DL visualization by sub-bandgap photo-excitation of trapped carriers. DLs with activation energies of EV + 1.05 eV, EV + 1.5 eV, and EV + 1.9 eV (or EC - 1.9 eV) were detected. The hole capture cross section of h = 4 × 10 -17 cm 2 is found using photoconductivity relaxation after sub-bandgap photo-excitation. Here, we found the DL defects responsible for non-radiative recombination and its impact on band alignment for the first time. Additionally, the transport properties of single crystal MAPbBr3 is measured by Time of Flight