Hot Carrier Dynamics in Lead Halide Perovskites: Mobility and Carrier-Phonon Coupling
Andrés Burgos-Caminal a, Aurélien Willauer a, Ahmad Ajdar Zadeh a, Jacques-E. Moser a
a Photochemical Dynamics Group, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV19)
Roma, Italy, 2019 May 12th - 15th
Organizers: Prashant Kamat, Filippo De Angelis and Aldo Di Carlo
Oral, Andrés Burgos-Caminal, presentation 108
Publication date: 11th February 2019

Time resolved terahertz spectroscopy (TRTS) is a very useful ultrafast laser spectroscopy technique for the study of charge carriers in semiconductors.[1] Its sensitivity to both carrier mobility and concentration can help elucidate the mechanisms of their temporal evolution. However, traditional techniques of THz generation and detection, such as optical rectification and electro-optic sampling, are generally limited in bandwidth and temporal resolution to <3THz and 0.5-1 ps, making the study of the early dynamics an arduous task susceptible to analysis errors due to the convolution with the instrument response function (IRF). The development of gas photonics helped to solve this problem with the generation and detection of ultra-broadband and short THz pulses, thanks to the air-biased coherent detection technique [2-3] and the use of dual color laser induced plasmas for generation.[4]

We present a study of the early charge carrier dynamics in lead halide perovskites from the point of view of THz mobility. These materials have become one of the dominant topics in solar energy research, thanks to their outstanding performance and facile processability. Taking advantage of our improved time resolution, down to 200 fs, we can temporally follow the cooling of hot carriers through changes in mobility. A link can be established between charge carrier cooling and the emergence of phonon-carrier interactions, possibly through the formation of a polaron.[5] However, the latter cannot be directly observed as a change of mobility when cold carriers are directly formed. We compare these results across different perovskite compositions to elucidate the role of cations and anions.

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