Synthesis of n-type perylene bisimide derivatives and their orthogonal self-assembly with p-type oligo (p-phylene vinylene)s

Four different (chiral) electron-deficient (n-type) perylene bisimides contg. aliph., arom., or ethyleneoxide side chaines have been synthesized and fully characterized. All of them form supramol. stacks in apolar methylcyclohexane (MCH) soln. as demonstrated by concn.- and temp.-dependent absorption, CD, and fluorescence studies. One deriv. was investigated in more detail in the solid state and proven to be liq. cryst. and capable of forming nanometer-sized fiberlike networks when drop-cast from MCH. Optical spectroscopy techniques show that perylene bisimide and an oligo(p-phenylene vinylene) (p-type) deriv. orthogonally self-assemble into sep. nanosized p-and n-type stacks in MCH. In contrast in toluene only molecularly dissolved species are present. In films deposited from MCH as well as from toluene photoinduced electron transfer takes place from the p-type material to the n-type material. As a result of the orthogonal self-assembly process, in films from MCH an ordered network of fibers was formed, whereas in films from toluene no ordering was obsd. However, probably due to the lateral orientation on the surface and the presence of long aliph. chains pointing toward the electrodes, efficient bulk heterojunction solar cells could not be constructed