The effect of TiO2 nanocrystal shape on the electrical properties of poly (styrene-b-methyl methacrylate) block copolymer based nanocomposites for solar cell application

Titanium dioxide (TiO2) nanocrystals were synthesized into two shapes, namely spherical and rod-like and used for the fabrication of polystyrene-block-poly(methyl methacrylate) (PSMMA) block copolymer based nanocomposites, which were employed as the active top layer of electro-devices for solar cell application. Electro-devices were designed using nanocomposites with high TiO2 nanocrystal contents (50-70 wt%) and for comparison as-synthesized TiO2 nanospheres (TiO(2)NSs) and TiO2 nanorods (TiO(2)NRs) were also used. The morphology of the electro-devices was studied by atomic force microscopy showing good nanocrystal dispersion. The electrical properties of the devices were investigated by PeakForce tunneling atomic force microscopy and Keithley semiconductor analyzer, which showed higher electrical current values for devices containing TiO(2)NRs in comparison to TiO(2)NSs. Remarkably, the influence of the PSMMA block copolymer on the improvement of the conductivity of the electrodevices was also assessed, demonstrating that the self-assembling ability of block copolymer can be beneficial to improve charge transfer in the fabricated electro-devices, thus representing relevant systems to be potentially developed for photovoltaic applications. Moreover, the absorbance of the prepared electro-devices in solar irradiation range was confirmed by UV-vis spectroscopy characterization. (C) 2015 Elsevier Ltd. All rights reserved.