Ultra-low EQE roll-off and marvelous efficiency perovskite quantum-dots light-emitting-diodes achieved by ligand passivation

Recently, perovskite quantum dots (PQDs) were employed as promising emitters in light-emitting diode devices (LEDs) mainly owing to their marvelous photoelectronics properties. However, these perovskite QLEDs suffered from the inefficient performance, especially their serious efficiency roll-off probably due to the exciton recombination dynamic in the interface of PQDs films and charge imbalance resulting from low electrical transportation. Herein, sodium dodecyl sulfate (SDS) was effectively introduced to synthesize PQDs with many excellent properties and eventually suppressed the efficiency roll-off of QLEDs. SDS-based PQDs films exhibited obviously enhanced radiative recombination, reduced trap density, and increased carrier mobility, especially the transportation of electrons. Therefore, the charge carrier was balanced at high current density together with the remarkably suppressed efficiency roll-off. QLEDs fabricated by SDS-capped PQDs exhibited significantly improved maximum brightness of 193,810 cd/m2, and achieve the external quantum efficiency of 10.13%. More importantly, the EQE roll-off of QLED optimized in the thickness of emitting layer was only 1.5% at the current density of 200 mA/cm2, representing a prominent achievement of our strategy.