Abstract
ABSTRACT
Breaking out‐of‐plane symmetry in graphene is essential to realize electrostatic control in next‐generation electronic devices. While Janus graphene, which bears chemically distinct top and bottom faces, is a promising architecture, establishing a controllable fabrication route and directly linking asymmetric chemistry to electronic transport remains challenging. In this study, we present a resist‐free, interface‐selective laser‐writing strategy that facilitates stepwise bottom‐to‐top covalent functionalization of graphene and enables controlled access to top‐, bottom‐, and asymmetric dual‐side configurations. Raman spectroscopy verifies that this Janus configuration reaches a substantial degree of functionalization, exhibiting a Raman‐derived defect distance (
L
D
) of approximately 1.5 nm. Kelvin probe force microscopy reveals configuration‐dependent electrostatic responses, with a change of contact potential difference of approximately 225 mV for Janus graphene. Back‐gated field‐effect transistors further reveal pronounced changes in charge transport, with the residual carrier density increasing to 5.92 × 10
12
cm
−2
in Janus graphene. Notably, comparison of the investigated configurations reveals a configuration‐dependent relationship between interfacial electrostatics and charge transport. Furthermore, lithographically pre‐patterned substrates enable spatially programmable Janus architectures via single‐step laser writing, providing a scalable platform for engineering symmetry‐broken two‐dimensional electronic materials.