Related Experiment Video
Updated: Feb 4, 2026

Epitaxial Growth of Perovskite Strontium Titanate on Germanium via Atomic Layer Deposition
Published on: July 26, 2016
Reversible Photoswitching Function in Atomic/Molecular-Layer-Deposited ZnO:Azobenzene Superlattice Thin Films
Aida Khayyami1, Maarit Karppinen1
1Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland.
Abstract:
We report new types of reversibly photoresponsive ZnO:azobenzene superlattice thin films fabricated through atomic/molecular-layer deposition (ALD/MLD) from diethylzinc, water, and 4,4'-azobenzene dicarboxylic acid precursors. In these ultrathin films, crystalline ZnO layers are interspersed with monomolecular photoactive azobenzene dicarboxylate layers. The thickness of the individual ZnO layers is precisely controlled by the number (m) of ALD cycles applied between two subsequent MLD cycles for the azobenzene layers; in our {[(Zn-O) +(Zn-O2-C-C6H4-N=N-C6H4-C-O2)] +(Zn-O) } samples, m ranges from 0 to 240. The photoresponsive behavior of the films is demonstrated with ultraviolet-visible spectroscopy; all the films are found to be photoreactive upon 360 nm irradiation, the kinetics of the resultant trans-cis photoisomerization somewhat depending on the superlattice structure. The reversibility of the photoisomerization reaction is then confirmed with a subsequent thermal treatment. Our work thus provides proof-of-concept evidence of the suitability of the ALD/MLD technology for the implementation of photoactive moieties such as azobenzene within an inorganic matrix as an attractive new methodology for creating novel light-switchable functional materials.
Related Concept Videos
Molecular Orbital Theory I
Molecular Models
Hybridization of Atomic Orbitals I
Atomic Orbitals
Phase Transitions: Sublimation and Deposition
Molecular Orbital Theory II

