Probing the Interlayer Coupling of Twisted Bilayer MoS$_{2}$ Using Photoluminescence Spectroscopy

Two-dimensional molybdenum disulfide (MoS$_{2})$ is a promising material for optoelectronic devices due to its strong and stable photoluminescence emissions. In this work, the photoluminescence spectra of twisted bilayer MoS$_{2}$ are investigated, revealing a tunability of the interlayer coupling of bilayer MoS$_{2}$. For the twisted angle 0$^{\circ}$ or 60$^{\circ}$, the photoluminescence from the trion and exciton of bilayer MoS$_{2}$ shows the highest intensity ratio, and the trion binding energy reaches its maximum value. For the twisted angle 30$^{\circ}$ or 90$^{\circ}$, the situation is the opposite. These experimental observations are mainly attributed to the change of the interlayer coupling with the twisted angles. The first-principles density functional theory analyses further confirm the change of the interlayer coupling with the twisted angle, and these analyses interpret and support our experimental results.