ИСТИНА

Crystals of thiophene−phenelyne co-oligomers (TPCOs) have great potential for organic optoelectronics. These materials were shown to combine efficient charge transport properties along with very high luminescence quantum efficiency. However conventional vacuum and solvent processing techniques for creating thin films based on TPCOs result in polycrystalline films with very high surface roughness. The surface roughness of organic semiconducting films is very important for making efficient device such as organic field effect transistor (OFET) or organic light emitting diode (OLED). Here we report on growth of large-area thin single-crystalline films of TPCOs with high surface quality from solvent and by using physical vapor transport (PVT) technique. Solvent growth methods include gas−liquid interface growth by using solvent−antisolvent crystallization (SAC), isothermal slow solvent evaporation, and isochoric cooling. Crystals were investigated by atomic force microscopy (AFM). We showthat both solution and vapor phase grown crystals can have molecularly flat surface on the scale of more than tens of microns. We were able to experimentally measure AFM roughness (RMS) less than 0.05 nm on the flat area of our crystal showing a great potential for making OFET.