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Portrait of Tönu Pullerits; Photo: Kennet Ruona

Tönu Pullerits

Professor

Portrait of Tönu Pullerits; Photo: Kennet Ruona

Thermally Activated Exciton Dissociation and Recombination Control the Carrier Dynamics in Organometal Halide Perovskite

Author

  • Tom J. Savenije
  • Carlito Ponseca
  • Lucas Kunneman
  • Mohamed Qenawy
  • Kaibo Zheng
  • Yuxi Tian
  • Qiushi Zhu
  • Sophie Canton
  • Ivan Scheblykin
  • Tönu Pullerits
  • Arkady Yartsev
  • Villy Sundström

Summary, in English

Solar cells based on organometal halide perovskites have seen rapidly increasing efficiencies, now exceeding 15%. Despite this progress, there is still limited knowledge on the fundamental photophysics. Here we use microwave photoconductance and photoluminescence measurements to investigate the temperature dependence of the carrier generation, mobility, and recombination in (CH3NH3)PbI3. At temperatures maintaining the tetragonal crystal phase of the perovskite, we find an exciton binding energy of about 32 meV, leading to a temperature-dependent yield of highly mobile (6.2 cm(2)/(V s) at 300 K) charge carriers. At higher laser intensities, second-order recombination with a rate constant of gamma = 13 x 10(-10) cm(3) s(-1) becomes apparent. Reducing the temperature results in increasing charge carrier mobilities following a T-1.6 dependence, which we attribute to a reduction in phonon scattering (Sigma mu = 16 cm(2)/(V s) at 165 K). Despite the fact that Sigma mu increases, gamma diminishes with a factor six, implying that charge recombination in (CH3NH3)PbI3 is temperature activated. The results underline the importance of the perovskite crystal structure, the exciton binding energy, and the activation energy for recombination as key factors in optimizing new perovskite materials.

Department/s

  • Chemical Physics
  • MAX IV Laboratory
  • NanoLund: Center for Nanoscience

Publishing year

2014

Language

English

Pages

2189-2194

Publication/Series

The Journal of Physical Chemistry Letters

Volume

5

Issue

13

Document type

Journal article

Publisher

The American Chemical Society (ACS)

Topic

  • Natural Sciences
  • Atom and Molecular Physics and Optics
  • Physical Sciences

Status

Published

ISBN/ISSN/Other

  • ISSN: 1948-7185