Star‐shaped molecules with pyrene‐containing π‐conjugated unitslinked by an organosiliconcore (Py3Si and Py3C) were prepared and their applications to thin‐film transistors (TFTs) and photovoltaic cells were studied. Bottom‐contact type TFTs with spin‐coated films of the star‐shaped compounds as the active layers were prepared and the field‐effect mobility (µFET) and Ion/Ioff ratios were determined