Ultrafast spectroscopy of hot carrier cooling in metal halide perovskite semiconductors

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Metal halide perovskites are rapidly emerging as outstanding semiconductors for optoelectronic devices, including as a photovoltaic for solar power. The electron-phonon interaction controls the intrinsic mobility of charges in metal halide perovskites, and determines the rate at which carriers lose energy. Energetic carriers in a solar cell typically lose their excess energy as heat, rather than usefully contributing to power generation. In this project the carrier mobility and cooling dynamics will be directly examined using a combination of ultrafast transient absorption spectroscopy and optical pump, THz probe spectroscopy, in perovskites with different compositions. A model will be developed to provide a quantitative description of the experimental carrier cooling dynamics, both with and with out a substantial population of hot phonons. The combined understanding from experiment and theory will allow changes in cooling dynamics for alloys with different metal cations (e.g. Pb or Sn) and different halide anions (e.g. I or Br) to be established. The aim is to provide fundamental insights into factors that alter carrier cooling in order to establish the potential to use hot carriers in future device architectures.