An Optically Programmable Surface Realized With Azobenzene-Functionalized Lotus Leaf and OLEDs

Abstract

Spatially programmable surface properties are important building blocks for future microfluidic and biosensor devices. We demonstrate switching of a photochromic surface with a blue organic light-emitting diode (OLED) suitable as an integrated on-chip light source. The surface of a positive polydimethylsiloxane (PDMS) replica of a fresh lotus leaf is covalently functionalized with a photoswitchable azobenzene selfassembled monolayer (SAM) employing "click chemistry." 80 % of the azobenzene molecules are switched from cis to trans state within 4 min of OLED irradiation. A spatially resolved study of the azobenzene switching properties on the naturally inhomogeneous lotus surface is conducted evaluating the transmission of a 355 nm laser beam. In the area of the leaf veins the highest change in the relative transmission of 100 % is obtained upon switching from trans form to cis form under UV illumination. In comparison, an azobenzene-functionalized flat glass surface exhibits only a 0.5 % change in the relative transmission.

Photoswitchable Macroscopic Solid Surfaces Based On Azobenzene‐Functionalized Polydopamine/Gold Nanoparticle Composite Materials: Formation, Isomerization and Ligand Exchange

“…[44] The drawback of this system was that the same UV-irradiation was responsible to cleave the disulfide bonds for surface reconstruction and also to drive the rotation of the motors. Orthogonally photoswitchable macroscopic surfaces have been reported on patterned surfaces using micro-contact printing [45] or on optically programmable artificial lotus leaf surfaces, [46] both of which require highly specialized experimental techniques and equipment. The partial or complete exchange of an array of molecular switches to another with different properties, to the best of our knowledge, has not been demonstrated on a macroscopic surface.…”

Diarylethenes in Optically Switchable Organic Light‐Emitting Diodes: Direct Investigation of the Reversible Charge Carrier Trapping Process

“…A reversible modulation of such properties can be achieved by irradiating the device with photons of energy sufficient to trigger the reversible dopant photo isomerization process. The most prominent classes of photochromic compounds which have been used successfully in photo-switchable technologies are azobenzenes [18][19][20][21][22] and diarylethenes (DAEs). [20,21] In particular, DAEs show a number of properties which are highly desirable for the design and fabrication of a variety of responsive systems: i) vastly different optical, electrical, and energetic properties between the two, thermally stable, isomers; ii) highly reversible and fatigue…”