Self‐Assembled Perovskite Nanowire Clusters for High Luminance Red Light‐Emitting Diodes

Bright red emission (620–650 nm) from perovskite light‐emitting diodes (PeLEDs) is usually achieved via a composition including both bromine and iodine anions, which results in poor performance and stability due to phase separation under operating conditions. Here a large‐scale ligand‐assisted reprecipitation method is devised with nonpolar solvent that enables the fabrication of CsPbI 3 nanowire clusters, emitting at 600 nm. The blue‐shift of this emission relative to that of bulk CsPbI 3 (≈700 nm) is attributed to quantum confinement in nanowires. The growth of the nanowires is along the [011] crystal direction and is vacancy driven, resulting in the healing of surface defects and thereby a high photoluminescence quantum yield of 91%. The clusters with ultralow trap density show remarkable structural and environmental stability. PeLEDs based on these clusters exhibit an external quantum efficiency of 6.2% with Commission Internationale de l'Eclairage coordinates of (0.66, 0.34), and record luminance of 13 644 cd m −2 of red electroluminescence. The half‐lifetime under an accelerated stability test is 13.5 min for an unencapsulated device in ambient conditions operating at an initial luminance of 11 500 cd m −2 , which corresponds to an estimated half‐lifetime of 694 h at 100 cd m −2 based on acceleration factor obtained by experimental testing.