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

Abstract

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.

Electroluminescence Principle and Performance Improvement of Metal Halide Perovskite Light‐Emitting Diodes

“…Quantum confinement (quasi‐2D, 0D quantum dots, nanoplatelets, and nanowires) and grain refinement are recognized strategies for increasing E b , thereby improving the luminescence performance of PeLEDs. [ 36,229,264 ]…”

“…Recently, a self‐assembled CsPbI 3 nanowire cluster with a strong quantum confinement effect was obtained for high‐luminance red PeLEDs (Figure 10e). [ 264 ] First, the abundant halogen defects and excess amine ligands on the surface of NCs induce their self‐assembly into nanowires. The self‐assembly of nanowires into nanoclusters is driven by vacancy defects.…”

Perovskite Quantum Dots with Ultralow Trap Density by Acid Etching‐Driven Ligand Exchange for High Luminance and Stable Pure‐Blue Light‐Emitting Diodes

“…The www.advmat.de www.advancedsciencenews.com faster rate of the radiative recombination process (compared with the nonradiative equivalent) for both the etched and treated QDs, was confirmed by their reduced trap-assisted nonradiative recombination losses. [18] The significantly increased radiative rate for the etched QDs can be attributed to the peeling of the imperfect octahedrons, caused by HBr etching. The subsequent ligand exchange process could further passivate the surface dangling bonds, resulting in the rapid reduction of the nonradiative rate of the treated QDs.…”

Magnetron sputtered ZnO electron transporting layers for high performance perovskite solar cells

“…The TRPL spectra (Fig. 10b) of film samples can be fitted with a bi-exponential function to evaluate decay lifetimes: [52][53][54][55]…”