High-Performance InP Quantum-Dot Light-Emitting Diodes with a NiO_<i>x</i> Nanoparticle-Embedded Hybrid Emissive Layer

Quantum-dot (QD) light-emitting diodes (QLEDs) are garnering significant attention owing to their superb optoelectrical properties, but the overinjection of electrons compared to holes into the emissive layer (EML) is still a critical obstacle to be resolved. Current approaches, such as inserting a charge-balancing interlayer and mixing p-type organic additives into the EML, face issues of process complexity and poor miscibility. In this work, we demonstrate efficient InP QLEDs by simply embedding NiO_<i>x</i> nanoparticles (NPs) into the EML which forms a homogeneous QD-metal oxide hybrid EML. Precisely changing the NiO_<i>x</i> NPs concentration enables an effective modulation of the valence state of the hybrid EML, while controlling the exciton quenching phenomena stemming from the metal oxide additives. Moreover, the inorganic hybrid EML exhibits superior electrical stability compared to that of typical organic additives. In detail, it possesses an upshifted valence state by approximately 0.2 eV, leading the QLEDs to a 3.7-fold increase in luminance, 1.7-fold improvement in external quantum efficiency, and 3-fold extension in operational half-lifetime, simultaneously. Comprehensive analyses on the optoelectrical and morphological characteristics confirm that the hybrid EML is suitable for realizing efficient and stable InP QLEDs via a simple fabrication method. Therefore, we expect that this approach would provide valuable insights into the development of high-performance and low-cost QLEDs.