Flexible paper-based solid state ionic diodes

Different from most ionic diodes which use water as the medium, in this paper, we reported flexible solid state ionic diodes without water during the fabrication and operation. The ionic diodes were fabricated by sandwiching a PEO-doped separator sheet between two paper sheets, respectively doped with AgNO3–polyethylene oxide (PEO) and KI–PEO electrolyte. The working mechanism of the solid diodes was based on the different electrochemical and participation reactions under different bias. The rectification ratio of the diode devices could reach 46 under an input AC voltage between ±1 V. The devices exhibited good flexibility and showed stable rectifying behavior after more than 800 bending cycles. The effects of plasticizer on the rectifying performances of diodes were systematically studied. The stability of the devices fabricated with or without plasticizer in PEO was investigated. The results showed that there was a trade-off between rectifying performance and stability.