Asymmetrically conducting interfaces are the building blocks of electronic devices. While p-n junction diodes made of seminal inorganic semiconductors with rectification ratios close to the theoretical limits are routinely fabricated, the analogous organic-inorganic and organic-organic interfaces are still too leaky to afford functional use. We report fabricating highly rectifying organic-inorganic interfaces by forming water-mediated hydrogen bonds between the hydrophilic surfaces of a hole-conducting polymer anode and a polycrystalline n-type metal oxide cathode. These hydrogen bonds simultaneously strengthen the anode-cathode electronic coupling, facilitate the matching between their incompatible surface structures, and passivate the detrimental surface imperfections. Compared to an analogous directly joined interface, our hydrogen-bonded Au-PEDOT:PSS-H2O-TiO2-Ti diodes demonstrate 105 times higher rectification ratios. These results illustrate the strong electronic coupling power of the hydrogen bonds on a macroscopic scale and underscore the hydrogen-bonded interfaces as the building blocks of fabricating organic electronic and optoelectronic devices. The presented interface model is anticipated to advance designing electronic devices based on the organic-organic and organic-inorganic hetero-interfaces. Described electronic implications of hydrogen bonding on the conductive polymer interfaces are anticipated to be impactful in the organic electronics and neuromorphic engineering.
Keywords: PEDOT:PSS; TiO2; conjugated polymer-metal oxide interface; electronic coupling; hydrogen bond; hygrometry; organic−inorganic diode; rectification ratio.