  Perovskite light-emitting diodes (PeLEDs) have emerged as a strong contender
for next-generation display and information technologies. However, similar to
perovskite solar cells, the poor operational stability remains the main
obstacle toward commercial applications. Here we demonstrate ultra-stable and
efficient PeLEDs with extraordinary operational lifetimes (T50) of 1.0x10^4 h,
2.8x10^4 h, 5.4x10^5 h, and 1.9x10^6 h at initial radiance (or current
densities) of 3.7 W/sr/m2 (~5 mA/cm2), 2.1 W/sr/m2 (~3.2 mA/cm2), 0.42 W/sr/m2
(~1.1 mA/cm2), and 0.21 W/sr/m2 (~0.7 mA/cm2) respectively, and external
quantum efficiencies of up to 22.8%. Key to this breakthrough is the
introduction of a dipolar molecular stabilizer, which serves two critical roles
simultaneously. First, it prevents the detrimental transformation and
decomposition of the alpha-phase FAPbI3 perovskite, by inhibiting the formation
of lead and iodide intermediates. Secondly, hysteresis-free device operation
and microscopic luminescence imaging experiments reveal substantially
suppressed ion migration in the emissive perovskite. The record-long PeLED
lifespans are encouraging, as they now satisfy the stability requirement for
commercial organic LEDs (OLEDs). These results remove the critical concern that
halide perovskite devices may be intrinsically unstable, paving the path toward
industrial applications.
