Partially-Screened Field Effect and Selective Carrier Injection at Organic Semiconductor/Graphene Heterointerface

Abstract

Due to the lack of a bandgap, applications of graphene require special device structures and engineering strategies to enable semiconducting characteristics at room temperature. To this end, graphene-based vertical field-effect transistors (VFETs) are emerging as one of the most promising candidates. Previous work attributed the current modulation primarily to gate-modulated graphene-semiconductor Schottky barrier. Here, we report the first experimental evidence that the partially screened field effect and selective carrier injection through graphene dominate the electronic transport at the organic semiconductor/graphene heterointerface. The new mechanistic insight allows us to rationally design graphene VFETs. Flexible organic/graphene VFETs with bending radius <1 mm and the output current per unit layout area equivalent to that of the best oxide planar FETs can be achieved. We suggest driving organic light emitting diodes with such VFETs as a promising application.

Vertical Organic Field‐Effect Transistors

“…[77] GE-VOFETs based on ion gel gate dielectric have also been investigated and the devices constructed with pentacene or PTCDI-C 8 as active layer exhibit high electrical performances with current density up to 100 mA cm −2 at a voltage below 1 V and a small subthreshold swing of 240 mV dec −1 . [78,79] Except for fullerene, many other organic semiconductors (n-and p-type materials), such as PCBM and P3HT, [26] PTCDI-C 13 , [34] PTCDI-C 8 , [80] PTCI-BPE, [34] pentacene, [34,80] CuPc, [34] and C 8 -BTBT, [81] have also been used in GE-VOFETs. The fullerenebased GE-VOFETs have been widely investigated in the aspects of its electrical and photoresponse properties, demonstrating improved performances with the optimization of devices structures and processing conditions.…”

“…Due to superior mechanical properties, graphene is always an outstanding material for flexible device. [34] In addition, VOFETs have demonstrated great potential in large-area electronics on flexible substrate and driving the OLED displays in a small layout area (Figure 10c). In planar transistors, the shortest channel length is about 1 µm or even much larger and the performance of planar transistors may significantly drop, which was ascribed to the formation of small cracks or dislocations inside the channel under repeated bending cycles.…”

“…This phenomenon will recedes in nonvolatile organic memory elements based on VOFETs. [34] Copyright 2015, American Chemical Society. Due to the short channel length, VOFETs offers a perfect platform for organic memory elements with fast memory operation.…”

“…Although there are numerous publications regarding planar OFETs and significant advances have been achieved, [22,23] an inherent disadvantage of planar OFETs is their relatively larger conducting channels (usually in micrometers or even much larger scales). [32][33][34][35] The aim of this review is to give a comprehensive summary on these big progress achieved in this field including the development of novel device architectures and potential applications, which is different from previous reviews that focus on operation mechanisms of VOFETs. In this context, vertical organic field-effect transistors (VOFETs) have gained special interests in organic electronics since its first report in 2004.…”

Strongly enhanced Raman scattering of Cu-phthalocyanine sandwiched between graphene and Au(111)

“…13 In fact, CuPc can provide intrinsic molecular junctions at the nanoscale. 19 On the other hand, graphene is chemically inert, optically highly transparent, and impermeable to small molecules, thereby acting as a perfect barrier to, e.g., oxygen and water. 20 The use of graphene as a quencher for electronic and vibrational excitations has also been reported.…”