Electric Field Controlled Single-Molecule Optical Switch by Through-Space Charge Transfer State

Abstract

Controlling the photon emission property of a single molecule is an important goal for nano-optics. We propose here a new mechanism for a single-molecule optical switch that utilizes the in situ electric field (EF) in biased metallic nanojunctions to control photon emission of molecules with through-space charge transfer (TSCT) excited states. The EF-induced Stark effect is capable of flipping the order of the bright noncharge transfer state and dark TSCT state, resulting in the anticipated switching behavior. The proposed mechanism was theoretically verified by scanning tunneling microscope-induced electroluminescence from a naphtalenediimide cyclophane molecule under experimentally accessible conditions. Simulations show that the proposed switching effect can be obtained by changing either bias polarity, which alters the polarization of the field, or tip-height, which affects the magnitude of the field. Our finding indicates that the in situ EF could play an important role in the design of optoelectronic molecular devices.

Organic Optoelectronic Devices Based on Through-Space Interaction

“…Without considering the EF effect, the EL energy (3.22 eV) and intensity were the same under both EFs, as in molecule from ref. 76 Copyright 2021, American Chemical Society.…”

Adsorption properties of a paracyclophane molecule on NaCl/Au surfaces: a first-principles study

“…The influences of the decoupling NaCl layers on the adsorption energy, charge transfer between the surface and the PCP molecule, differential charge density as well as the partial density of states (PDOS) of the PCP molecule were systematically investigated. These calculations could supply useful information for the experimental realization of cyclophane based single-molecule optical switches 26 as well as for further studies with similar setups.…”

“…In a recent work, a new type of electric field controlled single-molecule optical switch based on the through-space charge transfer electronic transitions between the two decks of a cyclophane derivative were proposed in a STM type junction based on theoretical calculations. 26 A crucial condition to achieve the desired luminescence on/off functionalities is that both decks of the molecule have to be decoupled from the STM substrate to minimize the molecule–substrate interaction and preserve the intrinsic molecular properties. For such a purpose, the self-decoupling ability of these special molecules will not be sufficient and the addition of external decoupling layers could be a viable way to decouple the entire molecule from the substrate.…”

CH3O Substitution Effect Revisited in the Vibrationally Resolved Laser-Induced Fluorescence Spectra of Methoxycyclohexoxy Radicals

“…Recently, we obtained the LIF spectrum of 3-methoxy-1-propoxy radical (CH 3 OCH 2 CH 2 CH 2 O) in a supersonic jet and identified a charge-transfer excited state involving the intramolecular electron transfer from the C–O–C p orbital to the radical O p orbital . Different from the strong electronegative halogen substituents, − CH 3 O can donate the electronic charge of its lone pairs via intramolecular hyperconjugative interaction or through σ bonds. − Due to the free rotation of carbon chains of the CH 3 OCH 2 CH 2 CH 2 O radical, the intramolecular hydrogen bonds formed in both the ground state and the charge-transfer excited state make it difficult to reveal the mechanism of charge transfer. In contrast, the chair structure of the cyclohexoxy radical provides unique substitution sites for studying the intramolecular charge transfer induced by CH 3 O substitution − and the influence on the LIF spectra of alkoxy radicals.…”