Manipulating Ion Migration for Highly Stable Light-Emitting Diodes with Single-Crystalline Organometal Halide Perovskite Microplatelets

Ion migration has been commonly observed
as a detrimental phenomenon
in organometal halide perovskite semiconductors, causing the measurement
hysteresis in solar cells and ultrashort operation lifetimes in light-emitting
diodes. In this work, ion migration is utilized for the formation
of a p-i-n junction at ambient temperature in single-crystalline organometal
halide perovskites. The junction is subsequently stabilized by quenching
the ionic movement at a low temperature. Such a strategy of manipulating
the ion migration has led to efficient single-crystalline light-emitting
diodes that emit 2.3 eV photons starting at 1.8 V and sustain a continuous
operation for 54 h at ∼5000 cd m–2 without
degradation of brightness. In addition, a whispering-gallery-mode
cavity and exciton–exciton interaction in the perovskite microplatelets
have both been observed that can be potentially useful for achieving
electrically driven laser diodes based on single-crystalline organometal
halide perovskite semiconductors.