Photoisomerization Dynamics in a Densely Packed Optically Transformable Azobenzene Monolayer

Abstract

Molecular monolayers that can be reconfigured through the use of external stimuli promise to enable the creation of interfaces with precisely selected dynamically adjustable physical and electronic properties with potential impact ranging from electronics to energy storage. Azobenzene-containing molecular monolayers have multiple stable molecular conformations but face a challenging nanoscale problem associated with understanding the basic mechanisms of reconfiguration. Time-resolved X-ray reflectivity studies show that the reconfiguration of a densely packed rhenium-azobenzene monolayer occurs in a period of many seconds. The degree of reconfiguration from trans to cis forms depends on the integrated UV fluence and has kinetics that are consistent with a mechanism in which the transformation occurs through the nucleation and growth of nanoscale two-dimensional regions of the cis isomer.

All-optical reversible control of integrated resonant cavity by a self-assembled azobenzene monolayer

“…Additionally, in the case of the azobenzene work, the reliance on a random or disordered deposition approach reduces the control over the magnitude of the light-molecule interaction. Covalent attachment of self-assembled monolayers of azobenzene on planar SiO2 [34,35] or Au [36,37] substrates have been reported previously [38][39][40]. This uniform coating strategy offers a route to surface functionalize ordered azobenzene layers on optical devices.…”

Observation of Collective Photoswitching in Free‐Standing TATA‐Based Azobenzenes on Au(111)

“…While in densely packed aliphatic azobenzene, SAMs switching is prevented; densely packed aromatic azobenzene SAMs exhibited reversible, collective photoswitching . The latter is surprising and was attributed largely to steric effects, caused by the rigidity of the molecule and stabilization of the cis isomer by intermolecular interactions . Furthermore, excitonic coupling was proposed to lead to cooperativity in diluted aliphatic azobenzene SAMs …”

Atomistic simulations of charge transport in photoswitchable organic-graphene hybrids

“…Notably, embedding photochromic SAMs in organic or hybrid field-effect transistors opens the way for the fine-tuning of both morphological and electronic properties of the interfaces at stake in the overall response of the device [3][4][5][6]. In the current library of photoswitches, azobenzene derivatives, which exhibit a reversible light-triggered isomerization between a stable trans and a metastable cis state, stand as the most commonly used [7][8][9][10][11][12][13][14][15].…”