Model of self assembled monolayer based molecular diodes made of ferrocenyl-alkanethiols

David Duche (1) , Ujwol Planchoke (1) , Florian-Xuan Dang (2) , Judikaël Le Rouzo (1) , Marc Bescond (1) , Jean-Jacques Simon (3) , Teodor Silviu Balaban (2) , Ludovic Escoubas (1)

1 IM2NP - Institut des Matériaux, de Microélectronique et des Nanosciences de Provence
2 ISM2 - Institut des Sciences Moléculaires de Marseille
3 OptoPV

There has been significant work investigating the use of self assembled monolayers (SAMs) made of ferrocenyl terminated alkanethiols for realizing molecular diodes, leading to remarkably large forward-to-reverse current rectification ratios. In this study, we use a multiband barrier tunneling model to examine the electrical properties of SAM-based molecular diodes made of HSC 9 Fc, HSC 11 Fc, and HSC i FcC 13Ài (0 i 13). Using our simple physical model, we reproduce the experimental data of charge transport across various ferrocenyl substituted alkanethiols performed by Nijhuis, Reus, and Whitesides [J. Am. Chem. Soc. 132, 18386–184016 (2010)] and Yuan et al. [Nat. Commun. 6, 6324 (2015)]. Especially, the model allows predicting the rectification direction in HSC i FcC 13Ài (0 i 13) based molecular diodes depending on the position of the ferrocenyl (Fc) moiety within the molecules. We show that the asymmetry of the barrier length at both sides of the Highest Occupied Molecular Orbital of the ferrocenyl moiety strongly contributes to the rectifying properties of ferrocenyl-alkanethiol based molecular junctions. Furthermore, our results reveal that bound and quasi-bound states play an important role in the charge transport.

Domaines: Matériaux; Chimie de coordination; Science des matériaux [cond-mat.mtrl-sci]

David Duche, Ujwol Planchoke, Florian-Xuan Dang, Judikaël Le Rouzo, Marc Bescond, et al.. Model of self assembled monolayer based molecular diodes made of ferrocenyl-alkanethiols. Journal of Applied Physics, 2017, 121 (11), pp.115503. ⟨10.1063/1.4978764⟩. ⟨hal-01683277⟩