Site-selectively fabricated phthalocyanine neutral radical nanocrystals: structure and electrical properties

Phthalocyanine neutral radical nanocrystals were site-selectively synthesized by nanoscale electrocrystallization. These nanocrystals were found to have a three-dimensional π–π stacking structure. In addition, a bottom-gate-type field-effect transistor (FET) structure could be readily fabricated by reusing two electrochemical electrodes employed during the electrocrystallization process as the source and drain electrodes. We found that the nanocrystals exhibited properties similar to that of a weak p-type material. The weakened Mott-insulating nature of the nanocrystals, owing to the three-dimensional π–π interactions, may mitigate the field effect in the crystals. We believe that nanoscale electrocrystallization can also be applied to obtain crystals of various organic molecules and that further enhancements of this method will lead to the development of environmentally friendly, next-generation nanofabrication processes.