Programmable nano-wrinkle induced room-temperature exciton localization in monolayer WSe₂

Localized states in two-dimensional transition metal dichalcogenides (TMDCs) have been the subject of intense study recently, largely due to the exciting prospect of their application in quantum information science. Despite the rapidly growing knowledge surrounding these emitters, their exact microscopic nature is still not fully understood. A popular approach for exploring quantum emission from these materials has been the use of pillars, particles, or other nanostructures to induce local strain. However, directly probing local correlations between strain and quantum emission has proven challenging due to the requirement for sub-diffraction spatial resolution. Motivated by recent theoretical and experimental evidence suggesting that nanoscale wrinkles are responsible for localized emission¹, here we focus on intentionally inducing wrinkles and mapping their photoluminescence (PL) using nano-optical techniques. We show that long-range wrinkle direction is controllable with patterned array design. Meanwhile, the strain environment around individual stressors is often highly heterogeneous due to the presence of ultrafine wrinkles that are less deterministic. Detailed PL maps reveal a wide range of low-energy emission peaks originating from these ultrafine wrinkles, and that the states can be tightly confined to regions < 10 nm, even at room temperature. This is promising evidence that, under the right conditions, room temperature quantum emission could be achievable in 2D TMDC systems.