Changing the morphology of polyaniline from a nanotube to a flat rectangular nanopipe by polymerizing in the presence of amino-functionalized reduced graphene oxide and its resulting increase in photocurrent

Amino-functionalized reduced graphene oxide (a-RGO) is used to change the morphology of polyaniline (PANI) and to increase the photocurrent in the PANI-a-RGO hybrid. The PANI morphology is changed from a nanotube to a flat rectangular nanopipe (FRNP) by the polymerization of aniline with a-RGO in acetic acid. Scanning (SEM) and transmission electron microscopy show the formation of FRNP morphology which varies by changing the PANI/a-RGO ratio in the hybrid. Time dependent SEM and Fourier transform infrared spectroscopy were used to investigate the mechanism of FRNP formation. Efficient (similar to 500 times) improvement in photocurrent is observed in FRNP over PANI nanotubes on irradiation with white light. The photoresponse is quite reproducible even after several cycles with a time interval of 100 s and in both the negative and positive bias photocurrent increases. A donor-acceptor based 'electron-hole' pair mechanism is proposed for the photocurrent behavior of FRNP. Using the PANI-a-RGO FRNP hybrid a dye sensitized solar cell with Rose Bengal dye is constructed yielding a power conversion efficiency of 2.012%. (c) 2012 Elsevier Ltd. All rights reserved.