Energy transfer and radiation damping in gold–MAPbI ₃ heterostructures

Coupling excitonic systems to propagating surface plasmon polaritons (SPPs) can potentially extend the length scale for energy transport. However, experimental visualization of these coupled states is challenging. Here, leakage radiation microscopy was used to examine the SPP modes in lithographically fabricated gold nanostripes (AuNS) coated with a thin film of methylammonium lead iodide (MAPbI₃). By combining real-space and momentum-resolved back focal plane imaging with wavelength-tunable excitation, dispersion relations, group velocities, propagation lengths, and, consequently, dephasing rates were extracted for the SPP modes. Compared to the bare AuNS structures, the AuNS/MAPbI₃ hybrid systems exhibit increased SPP attenuation, attributed to a combination of resonant energy transfer from the SPPs to the perovskite and increased radiation damping from the change in dielectric environment of the nanostripes. Higher-order SPP modes were also observed for the AuNS/MAPbI₃ system, allowing their group velocities to be determined.