Ultra-Low-Threshold Laser Patterning of Graphene With a Modular Sulfonium Library for Programmable Work-Function Engineering.

Achieving spatially resolved chemical functionalization on graphene lattices is essential for fabricating advanced two-dimensional (2D) architectures. However, current covalent patterning strategies struggle to simultaneously minimize energy input for lattice preservation and offer the chemical versatility required for fine-tuning the local doping state of the 2D lattice. Here, a modular diaryl-sulfonium platform is developed for the ultra-low-threshold covalent patterning of monolayer graphene, further enabling substituent-encoded pattern of local work-function. Driven by a highly efficient, graphene-mediated hot-electron single-electron transfer (SET) mechanism, this approach lowers activation barriers, enabling non-destructive patterning with laser powers as low as 0.10 mW and irradiation time of a few seconds-orders of magnitude lower than conventional photon-driven processes-thereby ensuring high pattern fidelity without thermal degradation. By incorporating a library of six chemically distinct σ-bound substituents (including phenyl, fluorophenyl, trifluoroethyl, vinyl, phenylthiophenyl, and bromoethyl) onto a unified sulfonium scaffold, precise control over local work-function can be achieved. Kelvin Probe Force Microscopy (KPFM) reveals a continuous, chemically tunable spectrum of surface potential shifts (ΔCPD from ∼30 to ∼300 mV). Combined with exceptional ambient stability and thermal erasability, this work offers a robust, energy-efficient paradigm for chemically encoding reconfigurable 2D electronic landscapes.