Photoluminescence Quenching in WSe${}_2$ via p-Doping Induced by Functionalized Rylene Dyes

Abstract

Hybrid heterostructures combining transition metal dichalcogenides (TMDs) with light-harvesting dyes are promising materials for next-generation optoelectronics. Yet, controlling and understanding interfacial charge transfer mechanisms in these complex systems remains a major challenge. Here, we investigate the microscopic origin of photoluminescence (PL) quenching in ${\text{WSe}}_2$ functionalized with a novel, strongly electron-deficient perylene monoimide dye, ${\text{CN}}_4\text{PMI}$. Experimentally, the hybridization induces a $\sim$97\% PL quenching in ${\text{WSe}}_2$, confirming substantial static charge transfer and increased $p$-doping from the dye. To isolate the dominant electronic mechanism, we investigate from first principles various interface morphologies, including differing molecular orientations and layer thicknesses. Our density-functional theory results confirm that ${\text{CN}}_4\text{PMI}$ acts as a strong electron acceptor, inducing $p$-doping and forming a type-II level alignment with all considered configurations, giving rise to a small or vanishing band gap. Based on these findings, we attribute the observed PL suppression in ${\text{WSe}}_2$ to these strong electronic interactions with the dye. Our study provides a clear and validated strategy for tailoring the electronic structure of TMDs through targeted, electron-deficient organic functionalization.