  Molybdenum disulfide (MoS2) has drawn great interest for tunable photonics
and optoelectronics advancement. Its solution processing, though scalable,
results in randomly networked ensembles of discrete nanosheets with compromised
properties for tunable device fabrication. Here, we show via density-functional
theory calculations that the electronic structure of the individual
solution-processed nanosheets can be modulated by external electric fields
collectively. Particularly, the nanosheets can form Stark ladders, leading to
variations in the underlying optical transition processes and thus, tunable
macroscopic optical properties of the ensembles. We experimentally confirm the
macroscopic electro-optical modulation employing solution-processed thin-films
of MoS2 and ferroelectric P(VDF-TrFE), and prove that the localized
polarization fields of P(VDF-TrFE) can modulate the optical properties of MoS2,
specifically, the optical absorption and photoluminescence on a macroscopic
scale. Given the scalability of solution processing, our results underpin the
potential of electro-optical modulation of solution-processed MoS2 for scalable
tunable photonics and optoelectronics. As an illustrative example, we
successfully demonstrate solution-processed electro-absorption modulators.
