  In this study, we highlight the potential of strain engineering in
graphene/hBN (hexagonal Boron nitride) 2D heterostructures, enabling their use
as wide-range light absorbers with significant implications for optoelectronic
applications. We systematically investigate the electronic and optical
properties of graphene/hBN under the application of strain, considering various
stacking geometries within the framework of density-functional theory. The
semimetallic graphene layer upon aligning on the insulating hexagonal boron
nitride sheet opens a few tens of meV band gap at the Dirac point due to the
induced on-site energy differences on the two sublattices of graphene. Here, we
demonstrate that by simultaneously tuning the interlayer distance and lattice
constant, this band gap can be significantly increased to 1 eV. Interestingly,
in both scenarios (small and large band gaps), the material undergoes a
transition from a semiconductor to a semimetallic state. Importantly, the
tunability of this band gap is strongly influenced by the specific stacking
configuration. We further explored the optical properties across a broad
spectrum, revealing that the presence of a strain-induced band gap
fundamentally alters how light interacts with the system.
