1 research outputs found
Eliminating Nanocrystal Surface Light Loss and Ion Migration to Achieve Bright Mixed-Halide Blue Perovskite LEDs
Blue light-emittin g diodes (LEDs) are important components
for
perovskite electroluminescence applications, which still suffer from
insufficient luminescence efficiency and poor stability. In Cl/Br
mixed perovskite NCs, surficial defects cause severe light failure
and ion migration, the in-depth mechanism of which is also not clear.
To gain insights into these issues, we employ the ligand post-addition
approach for mixed Cl/Br NCs by using octylammonium hydrobromide (OctBr)
ligands, which effectively decrease surficial light loss and block
ion migration pathways. The passivated CsPbCl1.5Br1.5 NCs exhibit exceptional blue emission with 95% PLQY, and
the electroluminescence spectra of LEDs are located at the initial
positions at the initial states. The treated NC blue devices show
a negligible color shift as the voltage increases, which proves that
electric-field-driven ion migration is drastically suppressed. In
addition, OctBr-treated CsPbCl1.5Br1.5 and CsPbClBr2 NC LEDs show high external quantum efficiencies of 2.42 and
3.05% for emission peaks at 456 and 480 nm, respectively. Our work
identified the nature of NC surface defects and provided a surficial
modification approach to develop high-performance and color-stable
blue mixed-halide perovskite LEDs