Structural and electrical properties of semicrystalline P3HT cast films onto Si/SiO2 surface are studied during the solidification under applied electric field in lateral OFET geometry. During evaporation of the solvent, the formation of P3HT crystallites is monitored simultaneously by time-resolved X-ray diffraction and by source-drain current measurements. The electrical current is reaching its maximum in two pronounced regimes already before complete solidification of the polymer as detected by X-ray diffraction intensities. The monitored complex time dependence of current and X-ray intensities reveals a highest conducting level for the gel-like state.