Synthesis And Characterization Of Transient Electronics Based On Zinc Oxide And Poly(3,4-ethylenedioxythiophene):Polystyrene Sulfonate Thin Films

Electronic devices have become essential and ubiquitous in daily life and personal entertainment of the public,while traditional electronics are more likely to cause contamination after elimination or damage.Therefore,it is critical important to develop and utilize biodegradable,recyclable,environmental friendly and less toxic materials to produce electronic devices,and the concept of transient electronics were proposed.Transient electronics are a class of devices designed to degrade,dissolve or disintegrate into non-toxic small molecule substances after a period of stable functioning.The degradation takes place under some certain stimulations,such as under high temperature,in solutions or exposed to bio-fluids.Silicon semiconductor has been widely applied in the field of traditional electronics.However,it is costly to be fabricated,slow to degrade and liable to crack under stress,which constrain its application in the field of transient electronics.Herein,the semiconducting metal oxides and organic semiconductors were utilized to replace traditional silicon materials,and green cheap approaches were adopted to fabricate transient devices,whose degradation process in aqueous solution were characterized as well.A transient hetero-junction diode,based on zinc oxide(Zn O)and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate(PEDOT:PSS)thin films,was fabricated via chemical bath deposition in aqueous solution and spin-coating,and a Zn O based transient resistive switching memory was fabricated through chemical bath deposition in organic solution.The threshold voltage of the diode was around +1.5 V and the rectification ratio was over 10.The set voltage of the resistive switching memory was approximately +0.5 V and the reset voltage was around-0.5 V.The resistance ratio between high and low resistance states was near 300.The demonstrated transient devices were able to operate properly in stable conditions and degraded easily in aqueous solution.Meanwhile,current approaches for characterizing the degradation process of semiconducting films are unable to reveal information of the interface between the film and the solution,and they are unable to be conducted in the solution.Therefore,we proposed to use electrochemical impedance spectroscopy to characterize the degradation process of the films in the solution.The failure and degradation of the film can be identified by analyzing the impedance characteristic of the film/solution interface.According to the electrochemical impedance spectrum,the Zn O film failed and degraded after 1 day immersion in the solution,while the PEDOT:PSS film degraded after 3 hours immersion,which accord well with the evolution of micro-and macro-morphology of the films.