How Exciton Interactions Control Spin-Depolarization in Layered Hybrid Perovskites.
basic_science · Level V
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- Record sourced from PubMed, PMID 32574069.
- Also identified by DOI 10.1021/acs.nanolett.0c00867.
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Abstract
Using circularly polarized broadband transient absorption, time-resolved circular photoluminescence, and transient Faraday rotation spectroscopy, we report that spin-dependent interactions have a significant impact on exciton energies and spin depolarization times in layered Ruddlesden-Popper hybrid metal-halide perovskites. In BA<sub>2</sub>FAPb<sub>2</sub>I<sub>7</sub>, we report that room-temperature spin lifetimes are largest (3.2 ps) at a carrier density of ∼10<sup>17</sup> cm<sup>-3</sup> with increasing depolarization rates at higher exciton densities. This indicates that many-body interactions reduce spin-lifetimes and outcompete the effect of D'yakonov-Perel precessional relaxation that has been previously reported at lower carrier densities. We further observe a dynamic circular dichroism that arises from a photoinduced polarization in the exciton distribution between total angular momentum states. Our findings provide fundamental and application relevant insights into the spin-dependent exciton-exciton interactions in layered hybrid perovskites.