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Updated: Oct 23, 2025

Low Pressure Vapor-assisted Solution Process for Tunable Band Gap Pinhole-free Methylammonium Lead Halide Perovskite Films
Published on: September 8, 2017
Energy Tuning of Electronic Spin Coherent Evolution in Methylammonium Lead Iodide Perovskites
Guadalupe Garcia-Arellano1, Gaëlle Trippé-Allard2, Laurent Legrand1
1CNRS, Institut des NanoSciences de Paris, Sorbonne Université, 4 place Jussieu, F-75005 Paris, France.
Abstract:
We investigated the coherent evolution of the electronic spin at low temperature in high-quality CH3NH3PbI3 polycrystalline films by picosecond-resolved photoinduced Faraday rotation. We show that this coherent evolution can be tuned by choosing the pump-probe energy within the lowest optical-absorption band, and we explain it as the result of two main contributions: the localized electron and the localized hole. Their corresponding amplitude ratios are not constant across the lowest absorption band-an observation which disqualifies a free exciton from being at the origin of the electronic spin coherent evolution. We measured a spin coherence time of localized electrons (holes) of 4.4 ns (3.7 ns) at 1.635 eV, which evolves to about 7 ns at 1.612 eV (the hole coherence time remains almost constant at lower energies). Finally, we provide a global image of the spin coherent evolution in bulk metal halide perovskite, which overcomes recent controversies.
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