Origin of B-Type Blinking at 2D/3D Heterojunction Interfaces

Photoluminescence blinking is a common phenomenon that occurs across various low-dimensional materials, like 0D quantum dots or 1D nanowires. Two blinking types in 0D and 1D systems have been observed and extensively studied, revealing the mechanisms of non-equilibrium photocarrier kinetics, thereby enhancing emission stability and optimizing emitter performance. However, the origin of blinking in 2D materials is still less understood compared to those in quantum dots and single molecules and only the A-type blinking has been reported. Here, a B-type photoluminescence blinking is identified at the WS₂/Si heterointerface through the statistics of fluorescence lifetime-intensity distribution. Temperature-dependent photoluminescence and transient absorption spectra show that the blinking arises from the dynamic competition between two hot carrier relaxation pathways: one leading to A exciton emission and the other to localized exciton recombination. Moreover, Förster resonance energy transfer modulates the localized exciton density at the heterointerface and sustains the blinking phenomenon, which is distinct from other B-type blinking. This B-type blinking broadens the understanding of photocarrier dynamics in 2D/3D systems, which will benefit the development of optoelectronic devices based on 2D materials.