Stable Universal 1‐ and 2‐Input Single‐Molecule Logic Gates

• Published in: Advanced materials (Weinheim) Vol. 34; no. 26; pp. e2202135 - n/a
• Main Authors: Liu, Ran, Han, Yingmei, Sun, Feng, Khatri, Gyan, Kwon, Jaesuk, Nickle, Cameron, Wang, Lejia, Wang, Chuan‐Kui, Thompson, Damien, Li, Zong‐Liang, Nijhuis, Christian A., del Barco, Enrique
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.07.2022
• Subjects: Circuits; Coulomb blockade; Electrons; Gates (circuits); Logic circuits; logic gates; Materials science; Mathematical analysis; molecular electronics; Molecular orbitals; single‐electron transistors; single‐molecule devices; Transistors; Logic gate; Molecular electronics; Molecular computing; Coulomb blockade; Single-electron transistor
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202202135

Controllable single‐molecule logic operations will enable development of reliable ultra‐minimalistic circuit elements for high‐density computing but require stable currents from multiple orthogonal inputs in molecular junctions. Utilizing the two unique adjacent conductive molecular orbitals (MOs) of gated Au/S‐(CH2)3‐Fc‐(CH2)9‐S/Au (Fc = ferrocene) single‐electron transistors (≈2 nm), a stable single‐electron logic calculator (SELC) is presented, which allows real‐time modulation of output current as a function of orthogonal input bias (Vb) and gate (Vg) voltages. Reliable and low‐voltage (ǀVbǀ ≤ 80 mV, ǀVgǀ ≤ 2 V) operations of the SELC depend upon the unambiguous association of current resonances with energy shifts of the MOs (which show an invariable, small energy separation of ≈100 meV) in response to the changes of voltages, which is confirmed by electron‐transport calculations. Stable multi‐logic operations based on the SELC modulated current conversions between the two resonances and Coulomb blockade regimes are demonstrated via the implementation of all universal 1‐input (YES/NOT/PASS_1/PASS_0) and 2‐input (AND/XOR/OR/NAND/NOR/INT/XNOR) logic gates. Single‐molecule logic devices are ideal candidates for ultra‐minimalistic circuit elements to perform high‐density computing. Gated Au/S‐(CH2)3‐Fc‐(CH2)9‐S/Au single‐electron transistors not only hold the advantage of controlling molecular orbitals (MOs) via bias and gate voltages, but also exhibit a unique electronic structure with two adjacent MOs. This provides a single‐electron logic calculator to implement all universal logic gates within a single‐molecule device.