Electronic transport properties of methylammonium lead iodide perovskite single crystals prepared by inverse temperature crystallisation have been investigated using dark current, steady state and transient photocurrent measurements. Above 250 K the dark conductivity at electric fields below 100 V/cm is thermally activated, with single activation energy 0.7 eV and magnitude 4×10 -8 S/cm at 300 K. At higher electric fields, conductivity increases as a power law suggesting space charge limitation. Steady state photoconductivity exhibits a roughly linear dependence on photon flux below 10 15 cm -2 s -1 and square root dependence above this, consistent with trap-limited and band-to-band recombination mechanisms respectively. Photocurrent overshoot and undershoot on a timescale of 10-100 s are observed on application and removal of a steady light source. Transient photocurrent measurements with temperature reveal a peak in the localised density of states 0.26 eV into the band gap, with an attempt to escape frequency of 10 11 s -1 . Deeper states are distributed exponentially with characteristic energy 54 meV, decreasing towards mid-gap.
|Journal||Journal of Physics: Conference Series|
|Publication status||Published - 4 Apr 2019|
|Event||20th International School of Condensed Matter Physics: Physics and Applications of Аdvanced and Multifunctional Materials - Hotel Joliot Curie, Varna, Bulgaria|
Duration: 3 Sep 2018 → 7 Sep 2018