Control of threshold voltage in pentacene thin-film transistors using carrier doping at the charge-transfer interface with organic acceptors

Well-controlled carrier doping was performed in pentacene thin-film transistors (TFTs) by depositing additional organic acceptor (F(4)TCNQ) layers on top of existing channels. The doping concentration could be predefined by changing the area covered with the acceptor layer, which provides control of the threshold gate voltage, while keeping both the field-effect mobility (similar to 1.0 cm(2)/V s) and the current on/off ratio (>10(5)). The transport properties of these devices are discussed in terms of the trap and release model for the doped organic TFTs. (C) 2005 American Institute of Physics.