Flattening Energy Puddles for Enhanced Charge Transport in Wrinkled WSe2

Abstract

Wrinkles, a prevalent form of line defect in monolayer (1L) 2D materials, significantly degrade their optoelectronic performance by inducing local strain, energy puddles, and charge trapping. This study introduces a wrinkle-selective strategy utilizing trioctylphosphine selenide (TOPSe), which exploits its steric hindrance and electron-donating nature to selectively heal selenium vacancies at strained wrinkle sites in 1L-WSe2. Comprehensive spectroscopic characterization—comprising Raman spectroscopy, photoluminescence spectroscopy, and femtosecond transient absorption microscopy—demonstrated substantial reductions in the defect density, suppressed non-radiative recombination, and prolonged exciton lifetimes. Kelvin probe force microscopy further revealed wrinkle-specific electron doping and spatial homogenization of the conduction band. Field-effect transistors based on TOPSe-treated 1L-WSe2 exhibited more than a two-fold increase in current and mobility, in conjunction with a transition from p-type to n-type conduction. Our findings indicate that wrinkle-targeted molecular engineering is a versatile approach for addressing intrinsic inhomogeneities in 2D materials and enabling high-performance optoelectronic devices.