AVS 58th Annual International Symposium and Exhibition
    Transparent Conductors and Printable Electronics Focus Topic Thursday Sessions
       Session TC+AS+EM-ThM

Paper TC+AS+EM-ThM9
Optical and Electronic Properties of Photonic Crystal Based Transparent Conductors

Thursday, November 3, 2011, 10:40 am, Room 106

Session: Transparent / Printable Electronics Part 1
Presenter: Sudarshan Narayanan, Carnegie Mellon University
Authors: S. Narayanan, Carnegie Mellon University
M. Bockstaller, Carnegie Mellon University
L. Porter, Carnegie Mellon University
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Transparent conductors are becoming ubiquitous in a host of civil and military applications, including transparent electrical contacts in solar cells and LEDs, heated glass for aircraft and automobile windows, and electrochromic devices and smart windows. However, finding abundant materials with optimal electrical and optical properties and that can be produced economically is a particular challenge. Moreover, limited supply and large demand, of late, for indium has inspired focused research on finding alternatives to ITO as a transparent conductor. We report here a novel approach to control optical properties such as absorption, transmission and reflection in multilayered structures (based on [1-2]) with absorbing components. Appropriate combination of materials could, among others, allow for applications like transparent electrodes, transparent electromagnetic shielding, flexible transparent conductors, etc. Through this study, we have demonstrated the validity of this approach using a few different materials combinations including polymer/metal and metal/ceramic systems. In these realizations the approach was shown to increase the transparency in the visible frequency range by ~ 3 orders of magnitude as compared to the reference materials. For example, transmittances of 30-50% of incident light in the visible region were measured for films containing a polymer (polystyrene – PS) and an amount of metal (gold – Au) that was 3-4 times as thick as its skin depth (~ 40-50 nm). We have also found compatibility between the observed experimental results and numerical simulations. Apart from enhanced optical transmittance, resisitivity values of ~ 10-4 Ωcm (comparable to Au films having ~ 10-5 Ωcm) have also been discovered in structures having insulating components. Our ongoing and future work is focused on alternative structures to enhance conductivity in the transverse direction as well as incorporate flexibility in the same. References: [1] M. Scalora et al., J. Appl. Phys. 83 5 (1998) 2377-2383 [2] M. Scalora, M. J. Bloemer, C. M. Bowden, Optics and Photonics News 10 9 (1999) 24-27