Electrohydrodynamic Jet-Printed MAPbBr3 Perovskite/Polyacrylonitrile Nanostructures for Water-Stable, Flexible, and Transparent Displays

The use of metal halide perovskite nanocrystals in display applications has garnered attention owing to their excellent optoelectronic properties, such as high color purity with an extremely narrow full width at half maximum and high photoluminescence quantum yield. Because metal halide perovskite nanocrystals, which are synthesized from precursor solutions, exhibit high crystallinity, research on high-resolution patterning has become popular owing to its cost-effectiveness and convenience for large-area processing. Various solution-based fabrication techniques, including lithographic approaches, electrospinning methods, and inkjet printing, have been employed to realize perovskite micropatterns for display applications. However, achieving high-resolution, transparent, and stable micropatterns in a time- and cost-effective manner remains challenging. Herein, we propose a cost-effective one-step electrohydrodynamic (EHD) jet-printing process for high-resolution, transparent, flexible, and stable methylammonium lead bromide/polyacrylonitrile (MAPbBr3/PAN) composite patterns and its surface nanomorphology control. We optimized the printing ink and processing conditions to not only generate a stable EHD jet but also ensure excellent optoelectronic properties of the MAPbBr3/PAN composite patterns. We parametrically observed its surface nanomorphology change from a nanoporous structure to a dense flat surface with the fabrication temperature. The MAPbBr3/PAN composite patterns fabricated under optimum conditions showed a high resolution of approximately 10 μm with high crystallinity, a high transmittance above 95% at visible wavelengths, and high stability under water for more than 20 days. The stability against water was attributed to the dense morphology formed at a processing temperature of 80 °C. In addition, the MAPbBr3/PAN composite patterns withstood 30,000 bending cycles with a 2 mm bending radius and 2% strain without a decrease in the photoluminescence intensity. The proposed EHD printing technique may open up intriguing possibilities for the fabrication of water-stable, transparent, and flexible display applications using metal halide perovskite nanocrystals.