Hexagonal Boron Nitride-Enhanced Optically Transparent Polymer Dielectric Inks for Printable Electronics.
Ng, Leonard WT
Advanced functional materials
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Zhu, X., Ng, L. W., Hu, G., Wu, T., Um, D., Macadam, N., & Hasan, T. (2020). Hexagonal Boron Nitride-Enhanced Optically Transparent Polymer Dielectric Inks for Printable Electronics.. Advanced functional materials, 30 (31), 2002339. https://doi.org/10.1002/adfm.202002339
Solution-processable thin-film dielectrics represent an important material family for large-area fully-printed electronics. Yet, in recent years, it has seen only limited development, and has mostly remained confined to pure polymers. Although it is possible to achieve excellent printability, these polymers have low (∼2-5) dielectric constants (εr). There have been recent attempts to use solution-processed two-dimensional (2D) hexagonal boron nitride (h-BN) as an alternative. However, the deposited h-BN flakes create porous thin-films, compromising their mechanical integrity, substrate adhesion and susceptibility to moisture. We address these challenges by developing a ‘one-pot’ formulation of polyurethane (PU)-based inks with h-BN nano-fillers. Our approach enables coating of pinhole-free, flexible PU+h-BN dielectric thin- films. We optimise the h-BN dispersion concentration with respect to exfoliation yield, optical transparency and thin-film uniformity. We achieve a maximum εr∼7.57, a two-fold increase over pure PU, with only 0.7 vol% h-BN in the dielectric thin-film. A high optical transparency of ∼78.0% (∼0.65% variation) is measured across a 25 cm2 area for a μm thick dielectric. The dielectric property of the composite is also consistent, with a measured areal capacitance variation of < 8% across 64 printed capacitors. Our formulation represents an optically transparent, flexible thin-film, with enhanced dielectric constant for printed electronics.
EPSRC funding acknowledged (EP/L016087/1)
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External DOI: https://doi.org/10.1002/adfm.202002339
This record's URL: https://www.repository.cam.ac.uk/handle/1810/304446
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