into next-generation organic electronics applications such as thin film transistors (TFTs), [1] organic photovoltaics (OPVs), [2][3][4] touch-sensitive interfaces, [5] and lightemitting diodes (LEDs). [6] Conventional metal oxide-derived conductive materials such as indium tin oxide (ITO) are still predominantly employed as TCEs due to their excellent electrical properties (R s = 10 Ω sq −1 ) and notable optical transparency (T = 90%). [7,8] Despite such favorable properties, the feasibility of ITO electrodes for mass production has recently come into question. High-cost sputtering deposition techniques combined with finite indium resources are key limitations towards scale-up potential, while its mechanical brittleness has made it a poor candidate for printable electronics. [9][10][11] Several viable flexible TCE alternative materials such as graphene, [12][13][14] carbon nanotubes, [12,[14][15][16] metallic nanowires, [17,18] metallic grids, [6,19,20] and hybrid films [21][22][23][24][25] have emerged to circumvent the challenges of ITO electrodes in device architectures. Silver metallic microgrids hold great potential as flexible TCEs due to their high degree of geometric tunability and versatility of available ink formulations compatible with high volume printing techniques such as screen-printing. [26,27] Ink formulations containing metal carboxylate salts, specifically silver neodecanoate (AgND), demonstrate a mechanically robust and highly conductive medium for fabricating silver features at low processing temperatures. [28][29][30] However, maximizing the electro-optical properties is key for TCE design to ensure that the payoff for high electrical performance does not negatively impact the resulting transparency of the electrode. Optimizing the electro-optical properties through careful selection of the TCE design, material selection and material processing conditions ensures that high conductive performance of the grids can be achieved with high optical transparency. One technique to improve the electro-optical properties of microgrid TCEs is to optimize the process that converts silver molecular ink into conductive and uniform metal traces. Photonic sintering in particular is an effective process to convert AgND into conductive Ag traces, with high line uniformity and density (increasing conductivity and reducing resistance). PhotonicThe 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 combinat...

sive, high throughput technology to integrate functional inks on low-temperature flexible substrates and to mass-fabricate electronics. A wide range of ink formulations have already been successfully incorporated into electronics using screenprinting, including flake-based ink, [7] nanowire inks, [8] nanoparticle (NP) inks, [9][10][11] and molecular inks. [12,13] Molecular inks derived from metal carboxylate salts have become a viable option to address costly or performative limitations exhibited by flake-based and NP inks. [13] They achieve high electrical performance due to their near bulk conductivity, and mechanically robust traces can be printed with low surface roughness and superior adhesion onto flexible substrates. Through the decomposition of the metal complex by means of photonic or thermal sintering, several ink formulations containing salts such as silver i) and copper ii) ethylene glycol carboxylates, and silver neodecanoate have all demonstrated a capacity to print highly conductive traces. [14][15][16] Silver neodecanoate (AgND) in particular can produce metallic traces that exhibit high current carrying capacity (CCC), low sheet resistivity, and low surface roughness upon printing. [13] Although AgND inks provide a performance-competitive alternative to particle-based inks, the high irradiative and thermal budget required to decompose and convert the ink to its metallic state necessitates a highly calibrated sintering sequence to avoid damaging the substrate.Printed electronics provide inexpensive and light weight electrical components to fuel emerging applications. One major challenge is the high temperature required to sinter conductive metal inks, which leads to thermal degradation of the substrate and subsequently poor performance. A boron nitride nanotube (BNNT) interfacial film is reported for thermal management in rapid processing of a printable silver molecular ink platform using intense pulsed light (IPL) sintering techniques. The inclusion of BNNT thin films of varying surface concentrations deposited between the substrate and the printed features reduces thermal damage to the substrate during sintering while simultaneously improving electrical performance, achieving a sheet resistance value as low as 140 mΩ sq −1 . A wide range of sintering energies ranging from 2.0 and 3.2 J cm −2 are investigated along with printed trace widths ranging from 5 mil (0.127 mm) to 20 mil (0.508 mm). Increases in the rate of cooling and in the current carrying capacity are confirmed with the inclusion of the BNNTs. Overall the thin coating of BNNTs presents no drawbacks while significantly improving the electrical properties of IPL sintered conductive traces and thus represents a simple approach that will advance the adoption of IPL for fabricating printed electronic components.

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