A fine-ordered nanostructured bismuth tin oxide thin film constructed via sol–gel nanopatterning for liquid crystal system

Nanoimprint lithography is a very convenient and cost-effective method, and when combined with a sol–gel process, can be used to simply accomplish the nanopatterning of a bismuth tin oxide (BTO) film. We achieved the transfer of a nanostructure to a solution-driven BTO film by using nanoimprint lithography for utilization as a liquid crystal (LC) alignment layer. A curing temperature of 250 ℃ was ideal for the transfer of the nanopattern from polydimethylsiloxane to a BTO film, as confirmed by using atomic force microscopy, scanning electron microscopy, and x-ray photoelectron spectroscopy. The nanopattern led to the uniform alignment of LC molecules, as confirmed via polarized optical microscopy and pretilt angle analysis. In addition, the nanopattern-imprinted BTO film showed great potential for LC applications due to its high thermal stability and optical transmittance, along with super-fast switching and low voltage operating electro-optical characteristics. Sol–gel nanopatterning of metal oxides is a convenient process to create LC-alignment films for application in diverse electro-optical devices.