Preparation Of Large Area Two-Dimensional Organic Semiconductor Single Crystal By Solution Method And Study On Low Power Devices

Two-dimensional organic semiconductor single crystals(OSSC)have long-range order of molecular arrangement,low grain boundary density,low impurities,low density defects,excellent flexibility,high transparency,and the potential of making highly integrated devices.The relationship between structure and performance reveals the intrinsic properties of organic semiconductor materials,exploring the way carriers are transported.Therefore,2D OSSCs are the best choice of high-performance OFET devices and large-area flexible integrated circuits.However,the method to prepare large-area 2D OSSCs still remains a huge challenge.The advantage of the solution method for growing organic single crystals is that it can be produced at room temperature under a more energy-saving and lower-cost way,wherein the solution shearing method is more advantageous for the preparation of a large-area organic single crystal device.Therefore,the development of a simple and efficient solution method for the preparation of highly ordered large-area 2D OSSC is of great significance for the intrinsic properties of organic single crystals and the exploration of more applications of organic single crystals.The first chapter of this thesis mainly discusses the development history of OFETs,various organic single crystal growth methods,high-k dielectric layer growth methods,the fabrication methods and applications of organic single crystal transistors.The second chapter discusses the improvement scheme of the solution shearing method from the perspective of fluid mechanics.Five kinds of centimeter-ordered organic P-type small-molecule semiconductors and two kinds of organic P-type polymer semiconductors are grown by solution shearing method.Compared with the conventional method,the coverage of the organic crystal on the substrate,the orientation and the uniformity of the crystal are largely improved.We prepared organic single crystal field effect transistors with high orientation and high uniformity.The devices all present high performance with a carrier mobility up to 19 cm~2/Vs.in ambient conditions.The third chapter discusses the preparation of high-k dielectric layers(Al O_x)using anodization method.Large-area organic single-crystal low-power field effect transistors are prepared on Al O_x substrates.Finally,the devices are saturated at-3V gate voltage,exhibited high carrier mobility up to 8 cm~2/Vs,and the subthreshold swing is as low as61 m V/dec,which is very close to theoretical limit ation.