Nucleation mechanism of metal-vapor atoms on photochromic diarylethene surface with a low glass transition temperature

Abstract

Metal pattern formation on organic surfaces is essential in organic electronics. Selective metal-vapor deposition using photochromic diarylethene (DAE) is a promising method to prepare fine metal patterns by maskless evaporation. Metal-vapor atoms are adsorbed, diffused, and then desorbed from the colorless surface with a low glass transition temperature. We, however, found that metal deposition started at a specific time (deposition-threshold time, tth) even on the colorless surface by continuous evaporation. tth was investigated using a quartz crystal microbalance. We elucidated that metal-nucleation sites were generated by chemical reactions between metal atoms and surface DAE molecules. The number of nucleation sites increases during metal evaporation and when the sites are located in the diffusion range of surface metal atoms, metal-atom nucleation for film-formation starts. This is the origin of tth. This result would provide important knowledge for the preparation of electrodes for organic devices based on selective metal-vapor deposition.