Engineering Silver Microgrids with a Boron Nitride Nanotube Interlayer for Highly Conductive and Flexible Transparent Heaters

Abstract The use of flexible transparent conductive electrodes (TCEs) as printed heaters offers unique advantages where transparency is a necessary design feature. Many existing TCE materials however suffer from poor flexibility and require complex fabrication processes and thus are not commercially viable for such applications. The design and process optimization of screen‐printable silver metal microgrids over a layer of boron nitride nanotubes (BNNT) to produce highly conductive and mechanically robust transparent heaters with high transparency and low power requirements is reported. Square and hexagonal geometries are investigated alongside varying line width and pitch combinations to produce 16 different grid designs with optical transparency ranging between 65% and 89% and resistance values as low as 2.90 Ω sq⁻¹. The BNNT thin film coating on polyethylene terephthalate substrates provides mechanical stability to the heater architecture by reducing the effects of deformation by up to 400%. The BNNT interlayer also contributes to an increase in thermal performance, achieving temperatures as high as 74.0 °C by initiating electrical sintering of the microgrids during heater operation which increases the Joule heating capacity of the features. Overall, this physical and material optimization provides a low‐cost, printable microgrid architecture for high performing and stable applications as TCE‐based heaters.