Chemical doping modulation of nonlinear photoluminescence properties in monolayer MoS₂

We demonstrate a simple modulation technique of nonlinear optical properties in monolayer (1L) MoS 2 via chemical doping. The strong nonlinear behavior of the exciton photoluminescence (PL) intensity is observed with increasing excitation power density for low-electron-density 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F 4 TCNQ)-doped 1L-MoS 2 , whereas the exciton PL intensity of as-prepared, heavily electron-doped 1L-MoS 2 exhibits weak sublinear behavior. These results are attributable to an enhanced exciton–exciton annihilation rate for the excitons in F 4 TCNQ-doped 1L-MoS 2 as the dominant decay pathway under strong optical excitation conditions.