Article Cite This: ACS Appl. Electron. Mater. XXXX, XXX, XXX−XXX
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Transparent Conductive Printable Meshes Based on Percolation Patterns Gurvinder Singh Khinda,† Matthew Strohmayer,‡ Darshana L. Weerawarne,† Jack P. Lombardi, III,† Natalya Tokranova,‡ James Castracane,‡ Carl A. Ventrice, Jr.,‡ Mark D. Poliks,*,† and Igor A. Levitsky*,§
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Systems Science and Industrial Engineering Department, Binghamton University-SUNY, 4400 Vestal Parkway East, Binghamton, New York 13902, United States ‡ Colleges of Nanoscale Science and Engineering, SUNY Polytechnic Institute, 257 Fuller Rd., Albany, New York 12203, United States § Corish, Inc., 150 Harvard St., Fall River, Massachusetts 02720, United States S Supporting Information *
ABSTRACT: Transparent conductive meshes were fabricated by inkjet printing on flexible substrate using a percolation pattern created by random removal of conducting bonds from a regular square two-dimensional lattice. With this approach, a higher gain in optical transmittance than electrical conductivity loss is achieved above the percolation threshold. As a result of this, a figure of merit for the percolation pattern is improved with respect to a regular square mesh. The transmittance (T), sheet resistance (R), and figure of merit (F) on percentage of removed bonds for square lattices were measured. The gain of the figure of merit was observed in the range of removed bonds from 5% to 15%. Our best samples exhibit T = 84%, R = 1.3 Ω/sq, and F = 130 × 10−3 Ω−1 (highest F value and lowest R value) and T = 93%, R = 8 Ω/sq, and F = 65 × 10−3 Ω−1 (highest T value). This demonstrates an excellent transparent conductive film (TCF) performance and is significantly better than any continuous TCF. The percolation meshes demonstrate good mechanical stability and the absence of a Moiré effect. A distinctive feature of this method is its universality and capability of being adapted to any symmetrical or asymmetrical pattern and deposition technique. KEYWORDS: transparent conductive films, percolation, conductive meshes, inkjet printing, sheet resistance, transmittance, figure of merit
1. INTRODUCTION The transparent conductive film (TCF) is one of the major components responsible for the performance of touch screens, flexible displays, thin film photovoltaic (PV) systems, smart windows, e-paper, and organic light-emitting diodes (OLEDs).1 Currently, the most widely used TFC is indium tin oxide (ITO). However, the TCF market needs an alternative to ITO due to its fragility, high cost, and the limited supply of indium. Therefore, ITO alternatives have attracted a great deal of attention from researchers in both academia and industry. Potential candidates to date include carbon nanotubes, graphene, metal nanowires, transparent oxides other than ITO, conductive polymers, and conductive meshes.2 Some ITO alternative technologies, like carbon nanotubes, graphene, and conductive polymers, cannot provide sufficiently low sheet resistance or are too expensive to be considered for high volume production. Metal nanowire networks that demonstrate a good performance (sheet resistance of 6−40 Ω/sq and transmittance of 85−91%) have been reported3−5. However, this coating has inherent problems with haze and surface roughness for sheet resistances below
