  The appearance of single photon sources in atomically thin semiconductors
holds great promises for the development of a flexible and ultra-compact
quantum technology, in which elastic strain engineering can be used to tailor
their emission properties. Here, we show a compact and hybrid
2D-semiconductor-piezoelectric device that allows for controlling the energy of
single photons emitted by quantum emitters localized in wrinkled WSe2
monolayers. We demonstrate that strain fields exerted by the piezoelectric
device can be used to tune the energy of localized excitons in WSe2 up to 18
meV in a reversible manner, while leaving the single photon purity unaffected
over a wide range. Interestingly, we find that the magnitude and in particular
the sign of the energy shift as a function of stress is emitter dependent. With
the help of finite element simulations we suggest a simple model that explains
our experimental observations and, furthermore, discloses that the type of
strain (tensile or compressive) experienced by the quantum emitters strongly
depends on their localization across the wrinkles. Our findings are of strong
relevance for the practical implementation of single photon devices based on
two-dimensional materials as well as for understanding the effects of strain on
their emission properties.
