• Kanemitsu, Yoshihiko

Abstract

<jats:p>Monitoring of the spatially resolved exciton spin dynamics in two-dimensional semiconductors has revealed the formation of a spatial pattern and long-range transport of the spin-polarized excitons, which holds promise for exciton-based spin-optoelectronic applications. However, the spatial evolution has been restricted to cryogenic temperatures because of the short exciton spin relaxation times at room temperature. Here, we report that two-dimensional halide perovskites can overcome this limitation owing to their relatively long exciton spin relaxation times and substantial exciton-exciton interactions. We demonstrate the emergence of a halo-like spatial profile in spin-polarized exciton population and its ultrafast expansion at room temperature by performing time-resolved Faraday rotation imaging of spin-polarized excitons in two-dimensional perovskite (C<jats:sub>4</jats:sub>H<jats:sub>9</jats:sub>NH<jats:sub>3</jats:sub>)<jats:sub>2</jats:sub>(CH<jats:sub>3</jats:sub>NH<jats:sub>3</jats:sub>)<jats:sub>3</jats:sub>Pb<jats:sub>4</jats:sub>I<jats:sub>13</jats:sub>. Exciton-exciton exchange interactions induce density-dependent nonlinear relaxation and ultrafast transport of exciton spins and give rise to a rapidly expanding halo-like spatial pattern. The density-dependent spatial control suggests the potential of using two-dimensional halide perovskites for spin-optoelectronic applications.</jats:p>

Topics

• density
• perovskite
• semiconductor
• two-dimensional