  While metals can be readily processed and reshaped by cold rolling, most bulk
inorganic semiconductors are brittle materials that tend to fracture when
plastically deformed. Manufacturing thin sheets and foils of inorganic
semiconductors is therefore a bottleneck problem, severely restricting their
use in flexible electronics applications. It was recently reported that a few
single-crystalline two-dimensional van der Waals (vdW) semiconductors, such as
InSe, are deformable under compressive stress. Here we demonstrate that
intralayer fracture toughness can be tailored via compositional design to make
inorganic semiconductors processable by cold rolling. We report systematic ab
initio calculations covering a range of van der Waals semiconductors homologous
to InSe, leading to material-property maps that forecast trends in both the
susceptibility to interlayer slip and the intralayer fracture toughness against
cracking. GaSe has been predicted, and experimentally confirmed, to be
practically amenable to being rolled to large (three quarters) thickness
reduction and length extension by a factor of three. Our findings open a new
realm of possibility for alloy selection and design towards processing-friendly
group-III chalcogenides for flexible electronic and thermoelectric
applications.
