Block Copolymer Templated Fabrication of TiO2 Nanodot Films Using Pulsed Laser Deposition


Block copolymer (BCP) templated inorganic material nanopatterning, often termed as BCP lithography, has received significant attention in recent years because of its self-assembly property offering direct synthesis of nanostructures with different morphologies. In this paper, we report an approach combining BCP template and pulsed laser deposition (PLD) to synthesize TiO2 nanodots of sub-50 nm dimension. Our results show that the BCP templated TiO2 nanodots maintained the exact form of the top of polystyrene cylindrical template in the growth process as seen from the top view of scanning electron microscopy images. X-ray photoelectron spectroscopy confirms the presence of Ti and O, and X-ray diffraction results show existence of both anatase and rutile TiO2 crystalline phase in the nanodot films. The photoluminescence spectrum for the fabricated TiO2 is dominated by a broad peak extending from visible to near-infrared (NIR) that appears because of overlap of the characteristic peaks for TiO2 anatase (visible) and rutile phase (NIR). The formation of crystalline TiO2 nanodots can be explained by crystallization by particle attachment phenomena around the BCP cylindrical domains during annealing. Fabrication of nanostructured titania or any other materials in combination with PLD and BCP as template has not been explored so far with the exception of lead titanate (PbTiO3) nanostructures; hence, our demonstrated approach could be extended to fabricate other inorganic nanostructures integrated with BCP lithography for optoelectronics, sensing, and catalysis applications.


Physics, Astronomy, and Materials Science

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Journal of Physical Chemistry C