Metal-nanowall grating transparent electrodes: Achieving high optical transmittance at high incident angles with minimal diffraction

Ping Kuang, Iowa State University
Joong-Mok Park, Iowa State University
Geyuan Liu, Iowa State University
Zhuo Ye, Iowa State University
Wai Y. Leung, Iowa State University
Sumit Chaudhary, Iowa State University
David W. Lynch, Iowa State University
Kai-Ming Ho, Iowa State University
Kristen P. Constant, Iowa State University

This paper was published in Optics Express 21 (2013): 2393 and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: doi:10.1364/OE.21.002393. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.

Abstract

A novel architecture has been employed to fabricate transparent electrodes with high conductivity and high optical transmittance at high incident angles. Soft lithography is used to fabricate polymer grating patterns onto which thin metallic films are deposited. Etching removes excess metal leaving tall walls of metal. Polymer encapsulation of the structure both protects the metal and minimizes diffraction. Transmission is dependent upon the height of the walls and encapsulation and varies from 60% to 80% for structures with heights of 1400 nm to 300 nm. In encapsulated structures, very little distortion is visible (either parallel to or perpendicular to standing walls) even at viewing angles 60° from the normal. Diffraction is at characterized through measurement of intensity for zeroth through third order diffraction spots. Encapsulation is shown to significantly reduce diffraction. Measurements are supported by optical simulations.