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

TL;DR

This study demonstrates that functionalized rylene dyes can induce significant p-doping and photoluminescence quenching in WSe₂ by acting as strong electron acceptors, revealing insights into interfacial charge transfer mechanisms.

Contribution

It provides a detailed first-principles analysis of how electron-deficient dyes induce p-doping and PL quenching in WSe₂, offering a strategy for electronic structure tailoring.

Findings

97% PL quenching in WSe₂ due to dye functionalization

CN₄PMI acts as a strong electron acceptor inducing p-doping

Type-II level alignment leads to small or vanishing band gap

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.