| Organic semiconductors have great potential applications in flexible electronics due to their low cost,solution processability and flexibility.Although the electrical properties of organic semiconductors have improved significantly during the past decades,the understanding of the charge transport mechanism of organic semiconductors is still lacking.In this thesis,high quality organic small molecule single crystal and organic semiconducting polymers were prepared to study the intrinsic transport properties of organic materials and the effects of charge doping.Detailed investigation of the electrical properties of these materials provides new insight into the charge transport mechanism of organic semiconductors.Firstly,the growth conditions of the rubrene single crystal by physical vapor transport,such as temperature and gas flow rate,were optimized for high quality samples.The growth of rubrene single crystals were characterized by optical microscopy and X-ray diffraction.The intrinsic mobility of rubrene crystals were measured with an air-gap field effect transistor geometry.The highest mobility was on the order of 10 cm2V-1S-1.In addition,semiconducting polymer Poly（diiododiacetylene）（PIDA）was prepared by topochemical polymerization.The electrical property of PIDA can be modified by vacuum annealing or by immersing in solution vapor,which is caused by graphitization.The conductivity of PIDA can be tuned by several order of magnitudes after graphitization.Low-temperature electrical transport measurements of PIDA show signatures of one-dimensional Mott variable-range hopping or Efros-Shklovskii variable-range hopping.We also found PIDA may be suitable for sensing of certain gas because its electrical conductivity responded to the piperidine gas concentration.For another polymer PC10-COOH,the preparation of its film was investigated with different methods and the surface morphology of the films were characterized by atomic force microscopy.The film has high electrical conductivity. |
