Coordinatively Attaching an Ultra‐Thin Boronate Ester Polymer Layer on the Surface of Monolayer MoS 2 for Heterostructures With Widely Tunable Electronic and Optoelectronic Properties

Abstract Covalent modification of monolayer 2D transition metal dichalcogenides (1L‐TMDs) such as 1L‐MoS 2 with organic species presents a promising strategy for developing advanced electronic and optoelectronic devices. However, a daunting challenge remains in the construction of an ultra‐thin polymer layer on the surface of 1L‐TMDs via covalent interaction. Herein, a coordination‐driven growth approach to attaching an ultra‐thin boronate ester polymer (BP) layer with precisely controlled thicknesses on the surface of 1L‐MoS 2 is demonstrated. The as‐formed BP‐MoS 2 heterostructures feature an atomically flat interface that facilitates ultrafast interlayer charge transfer. By tuning the BP layer thickness from several to over ten nanometers, BP‐MoS 2 enabled field‐effect transistors (FETs) demonstrate exceptional multi‐order‐of‐magnitude current modulation capabilities. BP‐MoS 2 photodetectors exhibit a remarkable 68‐fold enhancement in photocurrent switching ratio (≈3000) and an order‐of‐magnitude improvement in detectivity (1.7 × 10 12 Jones) compared to those of the pristine 1L‐MoS 2 device. Furthermore, the BP layer offers a robust platform for further surface decoration of 1L‐MoS 2 , because the boronate ester groups are highly active in anchoring metal ions. It is shown that anchoring lithium ions in BP evidently enhances carrier transport in the BP‐MoS 2 heterostructure. This strategy to covalently combine polymer layers and 1L‐TMDs may establish a versatile platform for designing functional heterostructures.