Entirely solution-processed and template-assisted fabrication of metal grids for flexible transparent electrodes

Abstract

A metal grid (MG) incorporated with a polymer substrate is a promising candidate for replacing indium tin oxide in flexible transparent electrodes (TEs). Here, a simple yet highly efficient method of fabricating a new class of flexible MG TEs based on wet chemical aluminum (Al) deposition on a seamless polymer mesh template is proposed. The polymer mesh template is readily fabricated by a single-step selective photo-curing of an ultraviolet-curable resin followed by conformal coating with solution-processed Al. The Al-coated mesh is then embedded in a polymer substrate, maintaining the smoothness of the device surface. The fabricated flexible MG TE exhibits a low sheet resistance of 10.6 ± 0.6 Ω sq⁻¹, high transmittance of 85.6 ± 1.4% at λ = 550 nm, and low haze of 3.2 ± 0.7% at λ = 550 nm. The electrical and optical properties of the device can be balanced by controlling the mesh geometry, with a high figure of merit of ∼220.4 that is comparable to those of next-generation flexible TEs. Moreover, the device is highly reliable and can maintain its excellent performance even after a cyclic tape peeling test (1000 times) and bending tests (1000 times each under tensile and compressive stresses). Based on the excellent optoelectronic performance in conjunction with the mechanical flexibility and stability, the MG TEs are successfully implemented in various flexible devices including transparent film heaters and touch screen panels.