Abstract
AbstractHydroxypropylcellulose (HPC) systems have been actively investigated as flexible transparent substrates for use in LCD technology. HPC solid films (20-60 μm) obtained from aqueous liquid crystalline solutions present tunable topography. The need for transparent contacts in working electronic devices leads to the study of the properties of Indium Tin Oxide (ITO) deposited on these flexible substrates. Substrates obtained from a 30% w/w solution of HPC in water (HPC30) were found to have an isotropic topography with a roughness (Ra ) of 18.4 nm as measured by atomic force microscopy (AFM). Substrates with an anisotropic topography were obtained from a 65% w/w HPC solution (HPC65). AFM measurements show a Ra = 29.1nm. Two types of peridiocities can be observed in HPC65 substrates. A primary set of large bands, perpendicular to the shear direction is characterized by a periodicity of 1.8-2.1 μm and an average peak-to-valley height of 74-87 nm. This first set of bands lies under a secondary set of smoother band texture with a periodicity of 0.35 – 0.40 μm and an average peak-to-valley height of 2.9-4.4 nm. Transport properties of ITO deposited on HPC30 substrates (ITO+HPC30) show a resistivity around 3x10-2 Ω.cm independent of orientation. ITO films deposited onto HPC65 substrates (ITO+HPC65) are conductive and show a resistivity which depends strongly on current direction about two orders of magnitude. The resistivity measured along the shearing direction is 3.8x10-2 Ω.cm and along a perpendicular direction is 2.7 Ω.cm. The anisotropic resistivity of ITO+HPC65 cannot be a direct consequence of the current path difference between both directions due to surface topography. The optical microscope observation of the ITO+HPC65 surface reveals the presence of cracks in the ITO film along the shear direction, which could be induced by the anisotropic mechanical properties of HPC65 substrates. The resistivity difference in ITO+HPC65 could be attributed to these cracks.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
