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 BA₂FAPb₂I₇, we report that room-temperature spin lifetimes are largest (3.2 ps) at a carrier density of ∼10¹⁷ cm^–3 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.

中文翻译：

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激子相互作用如何控制分层混合钙钛矿中的自旋去极化。

使用圆偏振宽带瞬态吸收，时间分辨的圆形光致发光和瞬态法拉第旋转光谱，我们报告了自旋依赖性相互作用对Ruddlesden-Popper混合金属卤化物钙钛矿中激子能量和自旋去极化时间有重大影响。在BA ₂ FAPb ₂ I _7中，我们报道了室温自旋寿命在载流子密度约为10 ¹⁷ cm ^–3时最大（3.2 ps）。在更高的激子密度下，去极化率会增加。这表明，多体相互作用减少了自旋寿命，并胜过了以前报道的载流子密度较低的D'yakonov-Perel进动弛豫的影响。我们进一步观察到动态圆二色性，它是由总角动量态之间的激子分布中的光致极化引起的。我们的发现为分层杂化钙钛矿中自旋相关的激子-激子相互作用提供了基础和应用方面的见解。