Charge Transport Characteristics of Diarylethene Photoswitching Single-Molecule Junctions

Abstract

We report on the experimental analysis of the charge transport through single-molecule junctions of the open and closed isomers of photoswitching molecules. Sulfur-free diarylethene molecules are developed and studied via electrical and optical measurements as well as density functional theory calculations. The single-molecule conductance and the current-voltage characteristics are measured in a mechanically controlled break-junction system at low temperatures. Comparing the results with the single-level transport model, we find an unexpected behavior of the current-dominating molecular orbital upon isomerization. We show that both the side chains and end groups of the molecules are crucial to understand the charge transport mechanism of photoswitching molecular junctions.

Optical properties of gold nanoparticles decorated with furan-based diarylethene photochromic molecules

“…Thus, it shows that photo-excited MO are not mixed with Au surface states like in the case of thiophene-base linkers which led consequently to partial loss of photochromic properties [13,21] . At the same time our linker provides sufficient π-conjugation in electronic transport measurements, as evidenced by recent molecular-break junction experiments [35] .…”

“…Furthermore we want to identify the correlations between collective switching of the ensemble and the processes undergone by a single YnPhT molecule between two gold nano-electrodes in molecular break junction setup. [35] As for the UV-induced ring-closing reaction we show that the molecule degradation is attenuated on gold nanoparticles. This will provide some advice to develop different approaches that drive or facilitate the electro-optical properties of molecules and devices on their basis at ambient conditions.…”

“…[33] The influence of the anchoring group on the electrical conductance through a single-molecule junction and the alignment of the MOs to the Fermi energy level of gold electrodes were systematically studied in a gold-break junction setup. [34][35] From this data it was concluded that for rather short molecules the nature of the anchoring group and side chain (i.e. -extended wires) is dominating the level alignment with respect to the Fermi-level of the electrode material.…”

Higher harmonics and ac transport from time dependent density functional theory

“…As an example, application of visible and UV light induces a reversible ring-opening/ring-closure reaction in some organic molecules that leads to sizable on/off ratios of the current [7,9,10]. Light emission from molecular junctions may also provide further means to characterize the device [11,12,13].…”

Nanopatterning of diarylethene films via selective dissolution of one photoisomer

“…Visible light irradiation of compound 1c opens the ring, breaking the conjugation length in half. 16 The central fluorocarbon tether acts as a throughspace electron density-withdrawing group and introduces a dipole in both isomers of compound 1. The longer p-conjugation length, i.e., larger conjugated electron density, in the closed form leads to a larger dipole moment than for the broken p-system of the open form.…”