2013 年 34 巻 4 号 p. 198-203
Ionic liquid has attracted much attention as a stable liquid even in vacuum, which feature has allowed us to propose a new application of the ionic liquid used as a crystallization solvent in a vacuum deposition process. In this review, we introduce a good example of the successful application to the vacuum deposition of single crystals and films of pentacene in ionic liquid. In this ionic liquid-assisted vacuum deposition, the pentacene is found to grow almost under the thermodynamic equilibrium condition with an aid of the ionic liquid, being of very high-quality in crystallinity as compared to those obtained by the simple vacuum deposition process without ionic liquid. The effects of not only the kind, but also the size and shape of the ionic liquids as the solvent on the initial nucleation and the subsequent growth of the pentacene crystal are discussed.