Electron density modulation in monolayer MoS₂ through the phase transition of a relaxor ferroelectric substrate

The integration of transition metal dichalcogenides (TMDs) with ferroelectric substrates is a powerful strategy to modulate their electronic and optical properties. However, the use of relaxor ferroelectrics for this purpose remains unexplored. Here, we demonstrate a reversible photoluminescence (PL) and charge density modulation of monolayer MoS₂ on a Sr_0.61Ba_0.39Nb₂O₆ (SBN) substrate, a prototypical relaxor ferroelectric. The smearing of the phase transition in SBN enables continuous tuning of MoS₂ electronic properties over a broad temperature range (30-90 °C). A pronounced PL enhancement occurs as the substrate transitions from ferroelectric to paraelectric phase due to the vanishing spontaneous polarization (P_S) and the consequent change in charge balance at the MoS₂/SBN interface. Moreover, thermal hysteresis in the electron density modulation is observed during heating and cooling cycles. These findings highlight the potential of relaxor ferroelectrics as reconfigurable platforms for electron doping and light-emission control in 2D materials, opening avenues for temperature-responsive optoelectronic and nanophotonic applications.