Preparation And Characterization Of Cobalt Phthalocyanine Organic Thin Film Transistors

Organic electronic devices have received much attention in recent years,and have a wide range of applications in the fields of flexible integrated circuits,sensors and stretchable electronic devices,among which metal phthalocyanines are ideal candidates for organic thin film transistor(OTFT)active layers due to their good chemical stability and easy synthesis in large quantities.In this paper,cobalt phthalocyanine(CoPc)is used as the active layer,and copper(Cu)and aluminum(Al)are used as electrodes.Organic thin-film diodes and organic thin-film transistors are prepared by vacuum evaporation and magnetron sputtering technology.The diode has a three-layer vertical structure Cu/CoPc/Al,and the transistor has a five-layer vertical structure Cu/CoPc/Al/CoPc/Cu.The electrical and photoelectrical properties of the prepared CoPc devices were characterized.The electrical and photoelectric parameters of the device are calculated,and the variation mechanism of output current,threshold voltage and barrier under illumination is analyzed.The effect of active layer thickness on device is studied and the aging characteristics of device are characterized.First,the I-V characteristics and photoelectric characteristics of CoPc organic film diode are characterized.Schottky contact is formed between Al electrode and CoPc film,CoPc diode has good rectifying characteristics.The optical parameters of the diode,including the filling factor FF and the photoelectric energy conversion efficiency?,were calculated to analyze the aging characteristics of the diode.Second,the static output characteristics of CoPc organic thin film transistors are characterized.The experimental results show that a good Schottky contact is formed between the CoPc film as the active layer and the Al gate.The output curve of the transistor shows unsaturated characteristics.When the gate-source voltage is 0V and the drain-source voltage is 3V,the maximum output current I_DS of the CoPc transistor is obtained=122?A,the current density is 30.5A/m~2,and the transconductance value g_m is calculated,Magnification?,conductivity?and carrier mobility and other parameters.Third,the photoelectric characteristics of CoPc organic thin film transistors are characterized.The experimental results show that the CoPc organic thin film transistor has good light responsivity.Under light,the maximum transconductance of the transistor increases by about7.1%,the threshold voltage of the transistor decreases by 0.1V,and the barrier decreases by 15.6me V.Test the switching characteristics of CoPc transistor under dynamic illumination.When the optical signal frequency is 500Hz,the SWITCHING time of CoPc transistor is in the millisecond level,with high response speed.Finally,the effects of other factors on the photoelectric characteristics of CoPc organic thin film transistors are characterized,including wavelength,brightness and thickness of CoPc thin film.By analyzing the aging characteristics of the transistor,the service life of the device can be extended more than twice when the transistor is stored in a vacuum chamber.