The Effect Of Electron-absorbing Groups On Organic Field Effect Transistors

As one of the most concerned organic electronic devices in the 21st century,the organic field effect transistor has achieved unprecedented development.Due to its flexibility and large area preparation compared with inorganic transistor,it has been widely used in electronic paper,sensors and radio-frequency identification cards.The performance of the device is mainly affected by the selection of various materials and the preparation process of the device.Among them,organic semiconductor materials as the active layer of the organic field effect transistor play a decisive role in the performance of the device,so they have been widely concerned by researchers.We could use the organic field effect transistor as a very effective means to understand the carrier transport performance and transmission.mechanism of organic semiconductor,which could provide more effective strategies and methods for the design and synthesis of organic semiconductor with higher performance.1.We designed and synthesized a kind of chlorine-containing oligomer to explore the influence of chlorine atoms on the electronic structure and molecular stacking mode of organic semiconductor materials.The experimental results show that the introduction of chlorine atoms lowered the energy level of the material,and the maximum absorption wavelength was also blue-shifted,which was caused by the electron-absorbing effect of chlorine atoms.We use the density functional theory to calculated the character of materials and the calculation are consistent with the experimental results.We also obtained single crystal structure by diffusion method,which proves that the steric hindrance effect of chlorine atom leads to the changes of molecular arrangement with torsion angle 60°.The results of device performance show that the mobility of chlorine substituted was up to 1.5 cm2 V-1 s-1,which was twice-time that of the unsubstituted materials.2.We design a series of naphthalene imide derivatives,and fluorine generation,and we discussed donor-acceptor structure unit of materials of the linear benzene and naphthalene imide and the influence of fluorination.We found that the maximum absorption wavelength would blue shift and energy level would decrease in fluorinated materials,which is due to the electron-absorbing effect of fluorine atom.We have prepared their organic single crystal field effect devices,and the results show that the fluorinated materials have better electrical properties than those not replaced by fluorinated materials,with two times higher mobility,smaller threshold voltage and larger Ion/off.3.We investigated the properties of organic single crystal field effect transistors with different cyano-substituted groups.The results show that different positions of substituents have great influence on the properties of materials,such as optical,electrochemical.We also preparing its single crystal devices to explore the transmission properties of organic semiconductor,found that different substituent position makes organic semiconductors have a different polarity.