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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 53: Perovskite and photovoltaics II (joint session HL/CPP)

CPP 53.3: Vortrag

Dienstag, 17. März 2020, 14:30–14:45, POT 251

Ultrafast vibrational dynamics in lead halide perovskites — •Ajay Jha¹, Hong-Guang Duan¹, Vandana Tiwari¹, Golibjon Berdiyorov², Alexey Akimov³, Pabitra Nayak⁴, Zheng Li¹, Hernry Snaith⁴, Michael Thorwart⁵, Mohamed Madjet², and R. J. Dwayne Miller^1,6 — ¹MPSD, Hamburg — ²Qatar Environment & Energy Research Institute, Doha — ³Department of Chemistry, State University of New York — ⁴Department of Physics, University of Oxford — ⁵I. Institut für Theoretische Physik, University of Hamburg — ⁶Departments of Chemistry and Physics, University of Tornoto

Hybrid organic-inorganic perovskites have gathered much attention owing to their unprecedented success in photovoltaics. To unravel the secrets to this success, we have studied the ultrafast dynamics of lead halide perovskites using heterodyne-detected transient grating and 2D spectroscopy in thin films for tetragonal (room temperature) and orthorhombic phases (T = 20 K). Our measurements capture the different ultrafast exciton dynamics in two phases of perovskite. In addition, we distinctly observe the ground and excited state vibrational modes corresponding to organic and inorganic sub-lattices in two phases. The interplay of strongly coupled dominant vibrational modes to ultrafast carrier generation process will be discussed. To rationalize our observations, we have employed density functional theory (DFT) predicting changes in the vibrational observations highlighting the importance of interaction between organic cation and inorganic sub-lattice in stabilization of charges upon photoexcitation.