In Situ Inkjet Printing Patterned Lead Halide Perovskite Quantum Dot Color Conversion Films by Using Cheap and Eco‐Friendly Aqueous Inks

Inkjet‐printed perovskite quantum dot (PQD) color conversion films (CCFs) have great potentials for mini/micro‐LED displays because of their ultrahigh color purity, tunable emissions, high efficiency, and high‐resolution. However, current PQD inks mainly use expensive, toxic, and flammable organic substances as solvents. In this work, water is proposed to be used as the solvent for inkjet printing PQD/polymer CCFs. The green‐emitting patterned MAPbBr3/polyvinyl alcohol (PVA) films are in situ prepared by using halides and the PVA‐based aqueous ink. The as‐printed CCFs exhibit a high‐resolution dot matrix of 90 µm with a bright green emission (λem = 526 nm), a high photoluminescence quantum yield of 85%, and a narrow full width at half maximum of 22 nm. They have both air‐ and photo‐stabilities under ambient conditions, and each pixel of CCFs is relatively uniform in morphology and fluorescence when the substrate temperature is 80 °C. The patterned blue‐emitting MAPbClxBr3‐x/PVA and red‐emitting Cs0.3MA0.7PbBrxI3‐x/PVA can also be printed by aqueous inks. These results indicate that the designed aqueous inks are promising for in situ inkjet printing high resolution and reliability PQD CCFs for mini/micro‐LED displays. Aqueous inks are first chosen for in situ printing patterned MAPbBr3 QD/PVA CCFs, which are optimized by varying substrate temperature. The CCFs exhibit excellent optical properties, high resolution, and good stability under ambient conditions. Furthermore, the fluorescence uniformity of the pixel is investigated by micro‐area PL spectra. Finally, the blue and red PQD/PVA CCFs are printed by changing the halogen ratio.