Fabrication of Perovskite Nanocrystal Light-Emitting\nDiodes via Inkjet Printing with High-Temperature Annealing

Abstract

Metal halide perovskite nanocrystals\n(NCs) have been considered\npromising materials for applications in light-emitting diodes (LEDs)\nbecause of their excellent optoelectronic properties. Inkjet printing\nis a promising solution-processed technique for perovskite NC LEDs\nbecause of the possibilities of using drop on-demand printing with\nefficient ink utilization. However, perovskite NCs are thermally unstable,\nwhich can cause irreversible phase transitions and optical quenching\nunder high-temperature annealing conditions. Here, we demonstrate\nan inkjet-printed CsPbBr₃ NC film for the fabrication of\nLEDs using high-boiling decalin and octane mixed solvents. The inkjet-printed\nCsPbBr₃ NC film exhibited a high photoluminescence quantum\nyield (PLQY) of 61.8% and retained its crystal structure even after\nhigh-temperature annealing at 200 °C, whereas the spin-coated\nCsPbBr₃ NC films showed a decrease in PLQY from 67.3% to\n30.6%. The inkjet-printed CsPbBr₃ NC LED with a bank-free\nstructure and large-area coating process exhibited a maximum luminance\nof 1890 cd m^–2 and a peak external quantum efficiency\nof 5.9%, which is a 6-fold higher efficiency than those of spin-coated\nCsPbBr₃ NC LEDs with a high-temperature annealing process.