Mixed-halide CsPb(Br/I)3 perovskite quantum
dots (QDs)
are regarded as one of the most promising candidates for pure-red
perovskite light-emitting diodes (PeLEDs) due to their precise spectral
tuning property. However, the lead-rich surface of these QDs usually
results in halide ion migration and nonradiative recombination loss,
which remains a great challenge for high-performance PeLEDs. To solve
the above issues, we employ a chelating agent of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic
acid hydrate (DOTA) to polish the lead-rich surface of the QDs and
meanwhile introduce a new ligand of 2,3-dimercaptosuccinic acid (DMSA)
to passivate surface defects of the QDs. This synchronous post-treatment
strategy results in high-quality CsPb(Br/I)3 QDs with suppressed
halide ion migration and an improved photoluminescence quantum yield,
which enables us to fabricate spectrally stable pure-red PeLEDs with
a peak external quantum efficiency of 23.2%, representing one of the
best performance pure-red PeLEDs based on mixed-halide CsPb(Br/I)3 QDs reported to date.