Solution-processable (Pc′)Eu(Pc′)Eu[TP(OH)PP]/rGO bilayer heterojunction organic transistors with exceptional excellent ambipolar performance

Abstract

For the purpose of fabricating next generation of microelectronics and photonics, the transistor that simultaneously provides high-efficiency charge transport and air-stable ambipolar performance becomes highly desired. In this paper, the bilayer heterojunction field-effect transistors, named as t-Pc-1/rGO (HFET-1) and t-Pc-2/rGO (HFET-2), are constructed for the first time by using a simple two-step solution-processing approach, in which the high conductive reduced graphene oxide (rGO) film as the sub-layer and the film of ambipolar sandwich mixed (phthalocyaninato)(porphyrinato) europium triple-deckers (Pc′)Eu(Pc′)Eu[TP(OH)PP] {Pc′ = Pc, [Pc(OPh)8]} (t-Pc-1, t-Pc-2) as the top layer, respectively. The resulting bilayer heterojunction devices exhibit significantly improved air-stable ambipolar performance with the carrier mobilities of ca. 107 to 108 fold higher than those of pristine triple-deckers, and the Ion/Ioff of 102 to 103 fold higher than that of the single-component rGO device. In particular, due to the heterojunction effect in an “accumulation mode”, the device HFET-2 shows the ultrahigh and balanced mobilities between hole, 30.9 cm2 V−1 s−1, and electron, 39.6 cm2 V−1 s−1, with the optimized ON/OFF ratio of 103 for both carriers, representing the best result for ambipolar OFET devices reported thus far.