Spontaneous Doping at the Polymer–Polymer Interface for High-Performance Organic Transistors

Low-k amorphous fluorinated polymers such as poly(perfluoroalkenylvinyl ether) (CYTOP) have widely been used as gate dielectrics for organic field-effect transistors (OFETs) because of their strong hydrophobicity to prevent the penetration of moisture and other contaminants and their perfect solvent orthogonality with organic semiconductors. Here, we report a new functionality of the fluorinated low-k polymer dielectrics, which is spontaneous p doping at the dielectric–semiconductor interface in OFETs. This functionality makes the ambipolar charge transport a unipolar p type. In the OFETs based on indacenodithiophene-co-benzothiadiazole and diketopyrrolopyrrole-thieno[3,2-b]thiophene, the charge transport is obviously ambipolar when paired with common polymer dielectrics such as poly(methyl methacrylate); however, it is perfectly modulated to the unipolar p type by applying the fluorinated dielectrics of CYTOP and poly(tetrafluoroethylene) (Teflon). We propose that this modulation of charge transport resu...