Microwave-assisted synthesis of sponge-like carbon nanotube arrays and their application in organic transistor devices

Abstract

Multi wall carbon nanotube (MWNT) sponges were synthesized with a domestic microwave oven. The procedure involves a mixture of graphite and cobalt acetate powders enclosed in an evacuated quartz ampoule exposed to microwave irradiation. Maximum yield of MWNT sponges of about 2.2 cm2 is obtained within 12 min of microwave exposure with individual MWNTs having diameters in the 20–50 nm range. Employing MWNT obtained from synthesized sponges we construct two types of organic transistors: a field effect OFET device in which the channel material is a MEH-PPV semiconducting polymer blended with the synthesized MWNT, and a light emitting transistor OLET device in which electrodes are prepared with MWNT, the channel material being the MEH-PPV polymer alone. These devices are characterized with I–V measurements. For the OFET device the Ion/Ioff figure is considerably improved by using the polymer/MWNT blend as channel. In the OLET device, I–V characteristics with MWNT electrodes are comparable to those obtained when ITO electrodes are used.