N-type Field Effect Transistor Based On Silane Cross-linked Dielectric Layer And Its Application In Inverter

Organic materials have been widely used in Organic field-effect transistors,OLED displays and solar cells due to their advantages of wide sources,low price,easy structure design and low-cost large-area solution processing.At present,organic electronics has become one of the more active research fields in chemistry and materials science.The performance of organic field effect transistor（OFETs）has been improved in recent decades,which device mobility has exceeded that of amorphous silicon device（1.0 cm²/Vs）.Its can be widely used in flexible display,electronic paper,RFID tag and memory.The hole mobility of p-type organic small molecule and polymer semiconductors is more than 20 cm²/Vs.For n-type organic semiconductors,the highest reported electron mobility is also more than 10 cm²/Vs.As an important part of transistor structure,the dielectric properties of organic dielectric layer play an important role in the device performance of organic transistor.High quality insulating material is the prerequisite for obtaining excellent performance.The cross-linked dielectric layer in the organic dielectric layer effectively reduces the leakage current by forming a dense cross-linked network,and reduces the thickness of the dielectric layer while ensuring the high dielectric properties of the dielectric layer.In addition to the basic insulation and physical properties,flexible devices have high mechanical flexibility and extensibility.Therefore,the silane cross-linked dielectric layer prepared by solution processing was researched in this paper,including three kinds of dielectric layers cross-linked with polyvinyl alcohol using ethoxysilane（TEOS）,chloropropylsiloxane（CPS）and 1H,1H,2H,2H perfluoromethyltrimethoxysilane（FS）as cross-linking agents.Because the main carriers of n-type semiconductor channel are electrons,which are sensitive to water and oxygen,compared with p-type organic semiconductor materials,the device performance of n-type semiconductor are inferior to p-type.Considering that n-type semiconductor plays an important role in bipolar transistors and complementary circuits,the research of new n-type semiconductor materials with high performance is still a focus in organic electronics.Therefore,on the basis of silane cross-linked dielectric layer,the device performance and morphology of n-type semiconductor N,N’-Ditridecylperylene-3,4,9,10-tetracarboxylic diimide(PTCDI-C₁₃)were further explored,and the device was applied to E/E saturated loaded inverter,and its static characteristics were analyzed.It mainly includes the following three parts:1、Firstly,organosilane cross-linked dielectric layers were prepared,and the surface properties and dielectric properties of the three kinds of silane cross-linked dielectric layers were characterized.The morphology of PTCDI-C₁₃films deposited on the cross-linked dielectric substrate was researched.The morphology of different base temperature and different substrate materials was analyzed.With the increase of substrate temperature,the crystal domain of the film increases,and reaches the maximum at 300℃.In addition,the surface energy of the substrate can also affect the morphology of the film.On the substrate with higher surface energy,the crystal domain of the film is larger,showing island growth;on the substrate with lower surface energy,the film shows the characteristics of fine and dense.2、The device based on silane crosslinking dielectric layer was prepared.Because the cross-linked dielectric layer has a large capacitance,the device has a lower working voltage and a higher mobility.The device mobility based on HPCPS reaches 0.39 cm²/Vs.The mobility of the device based on silane cross-linked dielectric layer is 8 times that of the modified device.Further research on the performance of modified devices shows that the mobility does not increase with the increase of the domain of the film,but decreases first and then increases.It may be because of the decrease of critical nucleation free energy and the increase of nucleation number in the process of low temperature nucleation,thus obtaining fine and continuous film morphology.The better connectivity makes the carrier of the transport layer can be obtained better transmission.3、E/E saturated load inverter based on PTCDI-C₁₃field effect transistor is fabricated.The logic threshold of the inverter is 5.80 V,which is close to the ideal logic threshold of 5 V.However the inverter has a large V_OLvalue,so it will lead to the failure of full output low voltage when the input voltage is high.It is necessary to adjust the channel ratio between the load transistor and the drive transistor to further improve.In addition,this paper also analyzes the operation mechanism of OFETs in E/E saturated load inverter.In conclusion,the work of this paper includes the preparation of high-performance silane cross-linked dielectric layer,and on this basis,the morphology and device performance of n-type semiconductor PTCDI-C₁₃thin film are researched,and the transistor device with single silane cross-linked dielectric layer is prepared,which shows high mobility.In addition,we also applied the device to the inverter,the inverter showed a better logic threshold,and analyzed the working mechanism of the inverter.The work of this paper shows that n-type semiconductor materials based on silane cross-linked dielectric layer can obtain high mobility and low operating voltage,and can be used in inverters,which provides the possibility for the development of flexible transistor devices.