Diverse types of molecules such as a donor-s-acceptor molecules and ferrocenyl alkanethiol have been suggested as potential candidates for the electronic component of a molecular rectifier.[1,2]  Recently, we demonstrated a novel strategy and design rule for realizing molecular-scale diode features based on the energy band engineering between simple alkanethiol or conjugated molecules and two-dimensional (2D) semiconductors.[3] Here, we firstly suggest a molecular-scale (sub-2nm) selector where is based on a heterojunction structure with a non-functional molecule(1-octanethiol, tridecafluoro-1-octanethiol) and two-dimensional semiconductor(MoS₂, WSe₂), which can be utilized to prevent the crosstalk signal in the crossbar memory array. According to direction of molecular dipole moment, the type of 2D semiconductors (1_L-MoS₂ of n-type), and the metal work function (Au and Pt), we found the nonlinearity at 1/2 V_r scheme can be significantly varied, e.x., 1.2± 10¹ for Au/C8/1_L-MoS₂/Au and 3.5 ± 10² for Au/F6H2/1_L-MoS₂/Pt. This phenomenon can be understood based on the interfacial energy band adjustment of 2D semiconductor in molecular heterojunction according to the direction of molecular dipole moment. The maximum non-linearity value is found to be 2.7± 10³ for the case of Au/F6H2/1_L-MoS₂/Pt, which never been demonstrated in the molecular-scale junction so far. With this non-linearity, the suggested molecular selector enables to extend the array size up to ~ 9Gbit crossbar array. This firstly suggested molecular-scale selector concept will give novel idea for the data storage application for the future technology in data storage application.
[1] Díez-Pérez, I. et al. Rectification and stability of a single molecular diode with controlled orientation. Nat. Chem. 1, 635 (2009).
[2] Chen, X. et al. Molecular diodes with rectification ratios exceeding 10⁵ driven by electrostatic interactions. Nat. Nanotechnol. 12, 797 (2017).
[3] Shin, J. et al.  Tunable rectification in a molecular heterojunction with two-dimensional semiconductors. Nat. Commun. 11, 1412 (2020).