Organic electronic devices using graphene and highly purified thin films of carbon nanotubes as transparent conductive electrodes.

摘要

The impressive electrical, optical and mechanical properties of thin films of single walled carbon nanotubes (SWNTs) and graphene have sparked intense interest and extensive research into these materials, with significant recent efforts seeking to incorporate them into organic electronic devices. Generally, this work has not taken full advantage of the unique properties of these materials, such as a low density of electronic states, mechanical flexibility and an enhanced surface area for charge injection. Progress has been further stymied by particulates in the SWNT material that creates vertical protrusions into the thin organic active layer.;This dissertation will discuss applications in which the unique properties of these materials can be tested or exploited in practical organic electronic devices. The low density of electronic states found in SWNTs and graphene allows for modulation of their Fermi level, providing a new degree of freedom for tuning electronic transport that was recently demonstrated in carbon nanotube-enabled vertical field effect transistors (CNVFETs). Thin films of SWNTs or graphene were used to probe this Schottky barrier height and width modulation and demonstrate the first graphene-enabled VFET, as well as demonstrating solution processable and n-type CN-VFETs. Additionally, thin films of SWNTs were incorporated into organic light emitting diodes and organic light emitting electrochemical cells to study whether the properties of the carbon nanotube films offer any intrinsic advantages over more conventional electrodes. The mechanical flexibility of the SWNT film also makes possible a new dual emissive device structure in which a light emitting electrochemical cell that incorporates transparent SWNT films as both anode and cathode to emit light in both the forward and reverse direction.;In addition to this device-based work, extensive research into carbon nanotube purification techniques will be discussed including the adaptation of a scalable purification technique not previously demonstrated with materials on this length scale. Material made available by this large-scale purification technique were incorporated into CN-VFETs that use the thinnest organic channels ever achieved in these devices. These projects offer insights into the special role that SWNTs can play in organic electronic devices.