Dipole-induced Organic Field-Effect Transistor Gated by Conjugated Polyelectrolyte

An n-channel organic field-effect transistor gated by a polyelectrolyte of poly[(9,9-bis(3'-((N,N-dimethyl)-N-ethylammonium)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] dibromide (PFNBr) has been studied. The carriers in this kind of electrolyte-gated transistors are induced by the strong dipoles in the PFNBr electrolyte which is different from traditional ion-induced electrolyte-gated transistors reported before. Thus, this kind of electrolyte-gated transistor shows fast response characteristic. An electron carrier density as high as 6 x 1014 charges/cm(2) at a gate voltage of only 2 V and an electron mobility as high as 0.1 cm(2) V-1 s(-1) are obtained due to the large capacitance of the PFNBr electrolyte. (C) 2009 The Japan Society of Applied Physics