“…20) With this background, we focused on the thin film heterostructure of copper phthalocyanine (CuPc), a representative p-type organic semiconductor material, on N,N'-Di-noctyl-3,4,9,10-perylenetetracarboxylic diimide (PTCDI-C8), a promising non-fullerene n-type organic semiconductor 21) with a high electron mobility of 1.7 cm 2 V −1 s −1 . 22) It is because this material combination can be a model system of the existing stacked structures consisting of n-alkyl perylene diimides and CuPc as p-n junction solar cells 23,24) or photodetectors, 25) though their structural information has scarcely been reported in detail so far. In this study, it was found that PTCDI-C8 which was vapor-deposited at relatively high temperatures formed large grains with an average size of a few hundred micrometers with a molecularly flat grain surface.…”