Influence of passivation with non-charged fluorinated ethylene propylene on the properties of pentacene organic thin film transistor

High electronegativity of non-charged fluorinated ethylene propylene (FEP) affected the performance of pentacene organic thin film transistors (OTFTs). The threshold voltage of the OTFT shifted from −14.7 V to −12.5 V without deterioration of on-off ratio and charge mobility. The degree of shift was related to the coverage of the FEP film on an active layer. No further shift was observed upon reaching the full coverage of surface at a 3-nm thickness of FEP. Encapsulation of the FEP-covered pentacene OTFT in a multilayer of PMMA/PUA/PET protected the device from oxygen and moisture.