Suppress Dark-Current for High-Photoresponse MoS2 Transistor

Due to the atomic thickness of 2D MoS2 film, the electronic structure is easily tunable by electric field and exhibits abundant property. However, due to the limit capacitance of inorganic dielectric, the tunability is still not well exhibited. Herein, a MoS2 phototransistor with large tunability driven by ion-gel film is fabricated. To improve the interface and reduce the dark current, the passivation layer is used to hinder the leakage current. With the passivation layer, there will be a specific barrier height on the interface of metal electrodes and ion-gel membrane. Under effect of the PVA (polyvinyl alcohol) passivation layer, the current on/off radio can reach 10(7) and the mobility can reach 6.54 cm(2)/(Vs) superior to the one without passivation layer. There is an abnormal behavior in the transistor including positive and negative photoresponse due to the coupling of the photogating effect and the adsorption of negative ion. The photoresponsivity can increase by 29 times which can reach 603.48 A W-1 at 400 nm illumination. Furthermore, the flexible transistor based on ion-gel can be demonstrated and it found that the transistor still has a considerable photoresponse with strain of 0.49%. This work provides a new solution for flexible wearable electronic and photoelectronic detection field.