Studies On Morphology Control Of Several Organic Semiconductor Thin Films And Performance Of Organic Field-effect Transistors,Photocatalysis

The organic field-effect transistors have important applications in the field of integrated circuits,display,sensors and organic lasers.How to improve the performance of field-effect transistors is an urgent problem to be solved.The photocatalyst can effectively utilize the sunlight to decompose water to make hydrogen and degrade the organic pollutants in the environment and solve the problems of energy shortage and environmental pollution.How to increase the catalytic activity of the catalyst is an important issue.The performance of organic field-effect transistors and the photocatalytic performance of organic semiconductors depend not only on the chemical structure of organic materials,but also on the morphology and structure of organic materials.Therefore in this papper,three kinds of semiconductor materials,copper phthalocyanine(CuPc),iron phthalocyanine(FePc)and perylene diimide(PDI)were studied.A series of organic field-effect transistors(OFET)with copper phthalocyanine as the active layer and a series of FePc thin films and PDI thin films were prepared by condition control.The relationship between the morphology,structure of CuPc thin films and field-effect transistor performance and the relationship between the morphology,structure of FePc thin films and PDI thin films and photocatalytic performance were studied.The corresponding research contents and results are as follows:1.The organic field-effect transistors with bottom-gate top-contact with CuPc as the active layer were prepared.CuPc was deposited in the vacuum,CuPc thin films were treated with seven solvents of different polarities.The relationship between organic solvent vapor,morphology and structure of CuPc thin films and prepared OFET performance were studied.CuPc thin films treated with petroleum ether,benzene and dichloromethane vapor showed nanorods,CuPc thin films treated with tetrahydrofuran and acetone vapor showed bamboo leaflike nanobelts,CuPc thin films treated with N,N-dimethylformamide(DMF)vapor showed nanorods with short thick-twisted twigs,CuPc thin films treated with ethanol vapor showed some small sporadic nanorods.The surface morphology of CuPc thin films was investigated at 0,10,20,and 60 min after the treatment with petroleum ether vapor.It could be seen that the change of morphology was due to rearrangement of CuPc molecules during solvent evaporation,rather than dissolution.The UV-vis and XRD analysis showed CuPc thin films treated with solvent vapor was polycrystalline,and 2 ? = 6.9°(d = 12.8 ?)had a sharp diffraction peak corresponding to 200 crystal planes,which indicated ?-FePc.The crystallinity increased and the grain size magnified after solvent vapor treatment,among them,the crystallinity of CuPc thin films treated with petroleum ether vapor was relatively largest and the grain size was the largest.The OFET performance test showed that the field-effect mobility of OFET prepared with CuPc thin films treated with the petroleum ether vapor was the highest,the switching ratio was the largest,and the threshold voltage was smaller.2.Photocatalytic degradation of rhodamine(RhB)under visible-light was performed using a photocatalyst of FePc thin film deposited on ITO glass,copper sheet and quartz glass.The FePc thin film was treated with solvent vapor with different polarity.The morphology and structure of the thin films were different at different processing times.The relationship between the morphology,structure,substrate,thickness of FePc thin films and the degradation rate of RhB was studied.The morphology of FePc thin films deposited on ITO glass treated with petroleum ether and DMF vapor for 0,24,36,48,72 h was different.The morphology of FePc thin films treated with petroleum ether vapor for 32 h showed nanorods.The morphology of FePc thin films treated with DMF vapor for 72 h showed nanosheets.The UV-vis and XRD analysis showed FePc thin films treated with solvent vapor were a polycrystalline structure,and 2 ? = 6.94°/6.98°(d = 12.8 ?)had a sharp diffraction peak corresponding to 200 crystal planes,which indicated ?-FePc.The intensity of the diffraction peak was the strongest and the crystallinity of FePc thin films was the largest after petroleum ether vapor treatment for 36 h and DMF vapor treatment for 72 h.These indicated the relative crystallinity of FePc/ITO thin films was the largest when the morphology of FePc/ITO thin films showed tightly arranged nanorods or a larger number and size nanosheets.At this time,the degradation rate of RhB by the FePc/ITO thin films reached the maximum of 32.9% and 33.8%,respectively.The photocatalytic performance of FePc thin films on different substrates was different.The photocatalytic performance of FePc/ITO and FePc/Cu thin films was larger than that of FePc thin films deposited on quartz glass.The photocatalytic performance of FePc thin films was related to the thickness of thin films.The thickness of the FePc/ITO thin films was 10 nm better than 50 nm.The photocatalytic performance of FePc/ITO thin films treated with DMF vapor indicated that the photocatalytic performance was almost constant and showed good reutilization character.3.Photodegradation of RhB by PDI thin films deposited on ITO glass(substrate temperature: 20,50,100,150,200 ?)was researched.The relationship between the substrate temperature,the morphology of PDI thin films and the degradation rate of RhB was studied.The results suggested that the morphology of PDI thin films showed larger worm-like nanoparticles intercalated with coarser nanorods with rounded cross-sections when the substrate temperature was 100 ?.at this time,the PDI thin films has the highest roughness,the largest specific surface area and the largest catalytic activity,degradation rate of RhB was the largest.