Synchronized Photoluminescence and Electrical Mobility Enhancement in 2D WS2 through Sequence-Specific Chemical Passivation

Two-dimensional (2D) semiconducting dichalcogenides hold exceptional promise as optoelectronic materials for next-generation electronic and photonic devices, as well as their hybrid circuits. Despite this potential, the pervasive presence of defects in 2D dichalcogenides results in carrier mobility and photoluminescence (PL) that fall significantly short of theoretical predictions. Although defect passivation offers a potential solution, its effects have been inconsistent. This inconsistency arises from the current materials and methods, which fail to achieve the desired binding chemistry and band structure engineering necessary to enhance optical and electrical properties simultaneously. In this work, we uncover new binding chemistry using a sequence-specific chemical passivation (SSCP) protocol based on 2-furanmethanothiol (FSH) and bis(trifluoromethane) sulfonimide lithium salt (Li-TFSI), which allows us to demonstrate a synchronized 100-fold enhancement in both carrier mobility and photoluminescence (PL) in WS2 monolayers. We propose a novel synergistic defect passivation mechanism, supported by ultrafast transient absorption spectroscopy (TA), Hard X-ray photoelectron spectroscopy (HAXPES), and density functional theory (DFT) calculations. Our findings establish a new performance benchmark for the optical and electronic properties of WS2 monolayers, paving the way for the development of more efficient and sustainable 2D semiconductor technologies.