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

Abstract

Selective metal deposition controlled by light irradiation was achieved for Zn, Mg, and Mn on a photochromic diarylethene (DAE) film; metal vapor atoms were deposited only on the colored film but not on the uncolored film. The deposition properties of the metals were strongly dependent on the deposition rates. Fine metal patterns were produced by laser scanning and a conventional vacuum-evaporation method without a shadow mask. Multiple-metal pattern preparation of Zn, Mg, and Mn via a maskless evaporation in a single vacuum process was also demonstrated.Organic electronic devices, which have advantages for various applications due to low cost, light weight, and flexibility, have been studied widely. 16 A vacuum-evaporation method with a shadow mask 7 or an ink-jet-printing process with metal nanoparticles 8 is generally used to prepare electrodes or wiring for the devices. However, it is difficult to further improve their resolution due to the complexity of the setup with a shadow mask system, or of thermal damage to the organic layer during heat treatment in an ink-jet-printing method.We have reported light-controllable selective Mg deposition on photochromic diarylethene (DAE) surfaces, where metal Mg atoms are deposited on a colored DAE surface but not on an uncolored surface by a vacuum-evaporation method.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. 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. 16,17 For a variety of industrial applications containing electronics and optics, the selective deposition of various metal species is desirable. We report here the selective deposition of Zn and Mn as well as Mg, and demonstrate metal pattering controlled by light irradiation with maskless vapor deposition. Results and DiscussionSelective Metal Deposition. Interaction of Metals and Deposition Rate Dependence: Figure 1 shows a photoisomerization of DAE. Selective Mg deposition means that an Mg film is formed on the colored DAE surface while not at all formed on the uncolored DAE surface by vacuum evaporation. Selectivity in Mg deposition is correlated with the difference in the T g of the DAE in its colored and uncolored states. The colored amorphous state has a T g of 95°C, whereas the uncolored state 32°C. 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 ...

Photochromism of Diarylethene Molecules and Crystals: Memories, Switches, and Actuators

“…855,856 The multiple-metal patterning with maskless evaporation via a single vacuum process was demonstrated as shown in Figure 81.…”

Selective Metal-vapor Deposition on Organic Surfaces

“…Selective metal‐vapor deposition for various metal species is possible by adjusting the deposition rate. Figure a shows the selective depositions for Zn, Mg, and Mn that depend on the deposition rate: 7 nm s −1 for Zn and 0.05 nm s −1 for Mn, which are higher and lower rates than those for Mg, respectively . Such R d dependence originates in the interaction between metal atoms and the surface during diffusion.…”

“…The parameters other than T g that affect metal‐atom desorption are the metal‐atom deposition rate (density on the surface), substrate temperature, gas pressure during the metal evaporation, surface viscosity, and the metal species themselves. Low deposition rate, high temperature, low gas pressure, and/or low viscosity facilitate easy desorption.…”

Selective metal deposition on photosensitive organic crystal surfaces

“…Light-controlled selective metal deposition based on photochromism of diarylethene (DAE) derivatives is a promising method for metal patterning. 14,15 Organic photochromism is defined as the reversible structural interconversion between two isomers with different colors upon irradiation by light at different wavelengths. 16,17 Metal vapor is deposited on a colored amorphous DAE surface but not on an uncolored one.…”