Resonant Dipole–Dipole\nInteraction: A Protocol\nto Amplify Weaker PL Emission in 2D MoS<sub>2</sub>

The\ndecade old challenge of achieving excitons at room temperature\nin conventional bulk semiconductors, limiting their applications in\nphotonic communication, has been overcome by the discovery of noncryogenic\nstable excitonic emission in 2D transition-metal dichalcogenides.\nThe pioneering detection of stable excitonic emission under ambient\nconditions in the 2D family was achieved with MoS<sub>2</sub>, featuring\ncharacteristic twin-peaked photoluminescence spectra characterized\nby a pronounced A exciton peak, alongside a weaker B exciton peak.\nThe accessibility and applicability of weaker exciton emissions are\nvery limited as compared to prominent exciton emissions, which restricts\nthe vast possibility of usage of weaker excitonic emissions spread\nacross a broad spectral range. In this article, we have demonstrated\na simple approach to selectively enhance weaker exciton emission through\nresonant dipole–dipole interaction. Our approach involves the\nutilization of a hybrid heterojunction, where the spectral overlap\nof excitonic emission between two materials leads to the dipole–dipole\nresonance effect and subsequently increases emission intensity. We\nhave targeted the inherently low-intensity B exciton emission feature\nof MoS<sub>2</sub> and coupled it with cuprous oxide (Cu<sub>2</sub>O) thin films, leveraging the strong spectral overlap between the\nintrinsic excitonic emission bands of Cu<sub>2</sub>O and the B exciton.\nFurthermore, we employed finite element analysis to investigate the\nimpact of the extinction response on the B exciton enhancement. Our\napproach provides versatility in selectively augmenting weaker exciton\nemission by leveraging the exploitation of exciton resonance between\ntwo materials, thereby amplifying emission intensity at the targeted\nwavelength.