An effective defect engineering strategy for giant photoluminescence enhancement of MoS2 monolayers

Two-dimensional (2D) transition metal dichalcogenide (TMDC) materials are considered as promising candidates to extend Moore's Law. However, the low photoluminescence (PL) quantum yield due to the inevitable defects during material preparation severely restricts its practical applications. Here, we report an effective defect engineering strategy for Sr-doped MoS2 that has been successfully achieved by a facile one-step chemical vapor deposition (CVD) method. PL enhancement up to two orders of magnitude, along with prolonged carrier lifetime, is obtained by doping the sample with a lateral size up to sub-millimeter level (similar to 324 mu m). Such an observed phenomenon is attributed to the transformation of negative trions to neutral excitons. Meanwhile, the radiation quality and stability of the doped samples are significantly improved. First-principles calculations further elucidate the underlying mechanism, that is, the introduction of appropriate complementary defect energy levels in MoS2 synergizes with its own defect energy levels to enhance the PL emission, rather than a simple doping effect. In addition, our defect strategy can also be applied to other dopant like calcium atoms. Our work demonstrates an effective defect engineering strategy to improve the PL performance of 2D TMDCs, which provides a promising approach for designing and engineering their optoelectronic properties for potential applications.