Solution prepared single crystal organic field‐effect transistors (OFETs) combine low‐cost with high performance due to structural ordering of molecules. However, in organic crystals polymorphism is a known phenomenon, which can have a crucial influence on charge transport. Here, the performance of solution‐prepared single crystal OFETs based on two different polymorphs of dithiophene‐tetrathiafulvalene, which were investigated by confocal Raman spectroscopy and X‐ray diffraction, are reported. OFET devices prepared using different configurations show that both polymorphs exhibited excellent device performance, although the α‐phase revealed charge carrier mobility between two and ten times higher in accordance to the closer stacking of the molecules.