25 August 2017 Ultrafast terahertz snapshots of excitonic Rydberg states and electronic coherence in an organometal halide perovskite CH3NH3PbI3
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Abstract
How photoexcitations evolve in time into Coulomb-bound electron and hole pairs, called excitons, and unbound charge carriers is a key cross-cutting issue in photovoltaic and optoelectronic technologies. Until now, the initial quantum dynamics following photoexcitation remains elusive in the organometal halide perovskite system. Here we reveal excitonic Rydberg states with distinct formation pathways by observing the multiple resonant internal quantum transitions using ultrafast terahertz quasi-particle transport. Nonequilibrium emergent states evolve with a complex co-existence of excitons, unbound carriers and phonons, where a delayed buildup of excitons under on- and off-resonant pumping conditions allows us to distinguish between the loss of electronic coherence and hot state cooling processes. The terahertz transport with rather long dephasing time and scattering processes due to discrete terahertz phonons in perovskites are distinct from conventional photovoltaic materials. In addition to providing implications for ultrafast coherent transport, these results break ground for a perovskite-based device paradigm for terahertz and coherent optoelectronics.
© (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Liang Luo, Long Men, Zhaoyu Liu, Yaroslav Mudryk, Xin Zhao, Yongxin Yao, Joong M. Park, Ruth Shinar, Joseph Shinar, Kai-Ming Ho, Ilias E. Perakis, Javier Vela, Jigang Wang, "Ultrafast terahertz snapshots of excitonic Rydberg states and electronic coherence in an organometal halide perovskite CH3NH3PbI3", Proc. SPIE 10363, Organic, Hybrid, and Perovskite Photovoltaics XVIII, 1036308 (25 August 2017); doi: 10.1117/12.2275492; https://doi.org/10.1117/12.2275492
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