Large‐Area Bright Emission of Plasmon‐Coupled Dark Excitons at Room Temperature

Abstract Brightening dark excitons in transition metal dichalcogenide monolayers (MLs) can provide large‐area ultrathin devices for applications in quantum information science and optoelectronics. For practical applications of dark excitons, a robust and bright emission over a wide area at room temperature is desirable; however, no reliable approach has been demonstrated thus far. In this study, an efficient approach is presented for brightening dark excitons at room temperature over a large area of a WSe₂ ML via coupling between plasmons and dark excitons. When a WSe₂ ML is placed on gold micropillars (Au MPs), dark excitons are efficiently coupled to strongly localized surface plasmons at the edges of the Au MPs, along with a strong photoluminescence (PL) emission. Room‐temperature dark exciton emission is confirmed via energy‐, angle‐, and time‐resolved spectroscopy experiments, as well as confocal PL mapping. This study provides a generalizable method for the practical application of dark exciton.