Enhanced Dielectric Screening and Photoluminescence from Nanopillar-Strained MoS2 Nanosheets: Implications for Strain Funneling in Optoelectronic Applications

Nonuniform strain on multilayer transition-metal dichalcogenide (TMDC) nanosheets is an exciting path toward practical optoelectronic devices, as it combines the advantages of localized control of optical and electronic properties with ease of fabrication. However, the weaker photoluminescence (PL) due to their indirect nature poses a challenge to their application. Here, we demonstrate extraordinary enhancement of PL from multilayer MoS2 nanosheets under nonuniform strain generated by nanopillars. We observe charge and exciton funneling to the pillar strain apex. The screening from the increased exciton and charge density lowers the exciton binding energy and renormalizes the band gap. Hence, we attribute the dramatic increase in PL to dissociation of bound excitons to free electron-hole pairs, showing that nonuniform strain on TMDC nanosheets can effectively manipulate the nature of light- matter interaction in these atomically thin materials for application in novel strain-engineered optoelectronics.

Automated summary

Nonuniform strain on multilayer transition-metal dichalcogenide nanosheets can dramatically enhance photoluminescence by causing charge and exciton funneling to strain apex, reducing exciton binding energy and renormalizing the band gap, leading to dissociation of bound excitons into free electron-hole pairs, demonstrating the potential for effective manipulation of light-matter interaction in these atomically thin materials for strain-engineered optoelectronics.