Giant Exciton Transport in hBN/2D-Perovskite Heterostructures

Abstract: Two-dimensional perovskites, such as Ruddlesden-Popper perovskites, exhibit outstanding optical properties and high exciton binding energies but are highly susceptible to degradation under photo- and electron-beam exposure. To overcome this limitation, we encapsulate the perovskites with mechanically exfoliated hexagonal boron nitride flakes, forming hexagonal boron nitride/perovskite heterostructures. Cathodoluminescence spectroscopy reveals that these heterostructures exhibit significantly reduced electron-beam-induced degradation, enhanced luminescence intensity, a narrower emission bandwidth, and an extended exciton decay time. Moreover, leveraging the scanning capability of our fiber-based cathodoluminescence spectroscopy technique, we demonstrate ultra-long-range exciton transport over distances of approximately 150 micrometers, attributed to exciton-defect coupling. This exciton-defect interaction not only enhances luminescence but also highlights the potential of hexagonal boron nitride/perovskite heterostructures as hybrid van-der-Waals systems with long-range exciton transport and slow radiative decay rates, paving the way for robust and efficient optoelectronic applications.