Fabrication and semiconducting properties of monodisperse n-type phthalocyanine nanograss

Dipotassium-2,3,9,10,16,17,23,24-octacyanophthalocyanine–potassium (K2Pc(CN)8–K) complex nanograss was fabricated on a single KCl crystal. The process was controlled to achieve monodisperse nanograss with individual rod diameters of 60nm and lengths of 250nm. The gaps between the rods were fully covered with K2Pc(CN)8–K complex grains. The film continuity at the interface between the substrate and the nanograss layer allowed measurement of the field-effect-transistor characteristics of the material. The K2Pc(CN)8–K complex film exhibited n-type conduction characteristics, and the energy of the highest occupied molecular orbital was determined to be 5.8eV. Organic photovoltaic cells containing K2Pc(CN)8–K as an n-type semiconductor were also fabricated, and the power-conversion efficiency of a cell containing vertical-aligned-nanograss was approximately four times larger than that of a nanograss dispersed bulk-heterojunction-type cell. ► Octacyanophthalocyanine nanograss was formed by chemical vapor deposition (CVD). ► The distribution of length of nanograss can be controlled by the temperature in CVD. ► The nanograss showed good n-type semiconductor property in photovoltaic cells.