Selective Metal Deposition on Photoswitchable Molecular Surfaces

Abstract

We report here a novel phenomenon: selective metal deposition on photoswitchable diarylethene (DAE) surfaces. Magnesium vapor was deposited by vacuum evaporation on the colored DAE but not on the uncolored surface. The selective deposition originates in the change of the glass transition temperature of the amorphous DAE film resulting from photoisomerization and therefore from changes of surface molecular motion. We clarified that Mg atoms on the uncolored surface actively migrated on the surface and were desorbed from the surface. The possibility of depositing other metals is also discussed. Light-controllable metal-integrated deposition was demonstrated as a new function of the photoswitchable molecular surfaces. This study reveals new features of the photoswitchable molecular surfaces, and their potential suggests bright prospects for future applications in organic electronics.

Light-Controlled Selective Metal Deposition on a Photochromic Diarylethene Film—Toward New Applications in Electronics and Photonics—

“…Because the interaction between Mg atoms and DAE surface molecules such as van der Waals' force is weak, Mg is desorbed from the uncolored surface by thermal energy even at ambient temperature. 9 Therefore, we tested the selective deposition for other metals such as Ca, Al, Mn, and Ag, simply by evaporating those metals to the colored and the uncolored surfaces. Our first try to extend the selective deposition to other metals, however, was unsuccessful; metal vapor atoms were deposited on both the colored and the uncolored surfaces.…”

“…Figure 4c shows that large Zn crystals with a diameter of 100500 nm (i) were formed on the colored film at a low deposition rate, whereas quite small crystals with a diameter of several tens nanometers (ii) were formed on the uncolored film at a high deposition rate. We have previously reported 9,10 that the collision between the metal and the surface is non-elastic, therefore in general, adsorbed atoms migrate on the surfaces of the films, and a collision between the metal atoms during migration results in nucleation to form crystals. The crystal size therefore, reflects the migration length and the density of the atoms at the surfaces.…”

“…9,10 Photochromism is defined as a reversible change in color induced by light irradiation. 11 The selective Mg deposition originates from large glass-transition temperature (T g ) change in the amorphous organic film in response to photoreaction.…”

“…11 The selective Mg deposition originates from large glass-transition temperature (T g ) change in the amorphous organic film in response to photoreaction. 9,12 An essential factor of the selective Mg deposition is desorption of Mg atoms from the uncolored surface due to active surface-molecular motion caused by the low T g . Mg is an important cathode material in organic electronics, 1315 and therefore the selective Mg deposition can be applied to fine cathode preparation for organic devices.…”

Synthesis, photochromism and fluorescence of new diarylethene bearing a benzofuran unit

“…Photochromic diarylethene compounds have received intense interest because of their potential applications in the area of optoelectronics such as optical recording, photo-switching, and full-color display devices [1][2][3][4][5][6]. Among the numerous reported photochromic compounds, diarylethene derivatives have been achieved much attention because of their outstanding fatigue resistance and thermally irreversible photochromic behavior [7][8][9].…”