Mechanism of Long-Range Energy Transfer from Quantum Dots to Black Phosphorus

This study explores the mechanisms of long-range energy transfer (EnT) from a self-assembled film of CdSe/ZnS core–shell quantum dots (QDs) to exfoliated black phosphorus (BP) nanoflakes through an AlOx encapsulation layer of variable thickness. The dependence of the EnT rate on donor–acceptor distance, d, scales as ∼d–2.3, which is shallower than the expected scaling for Förster-type EnT from a zero-dimensional (0D) donor to a 2D or 3D acceptor. Electrodynamic simulations reveal that the efficient long-range EnT is primarily attributable to the high areal concentration of the QD film, which results in scattering of the donor QD dipole field by neighboring QDs, thereby effectively increasing the area over which the donor and acceptor couple. This quantitative understanding of the photosensitization of BP through a passivating dielectric layer will help guide the development of high-performance optoelectronic devices based on ambient-reactive layered semiconductors.