Colloidal ZnO nanoparticles (NPs) are widely used as an electron-transporting layer (ETL) in the solution-processed quantum-dot light-emitting diodes (QD-LEDs). However, the inherent drawbacks including surface defect sites and unbalanced charge injection prevent the device from realizing their further performance enhancement. In this work, a series of Mg doped ZnO (ZnO:Mg) and chloride-passivated ZnO (Cl@ZnO) NPs were synthesized by using a solution-precipitation strategy, and they exhibited tunable optical bandgaps and upward-shift of conduction-band maximum (CBM). Solution-processed QD-LEDs based on cadmium-free Cu-In-Zn-S/ZnS (CIZS/ZnS) nanocrystals (NCs) were fabricated by using ZnO:Mg and Cl@ZnO NPs as the ETLs, whose maximum peak external quantum efficiency (EQE) was nearly twice as high as that of QD-LEDs using ZnO NPs as the ETL (EQE = 1.54%). To take advantage of the benefits of ZnO:Mg and Cl@ZnO NPs, Cl@ZnO:Mg NPs were developed through the integration of Mg doping and Cl-passivation. Surprisingly, the cadmium-free QD-LEDs with the Cl@ZnO:Mg NPs as the ETL exhibited a maximum peak EQE of 3.72% and current efficiency of 11.08 cd A–1, which could be enhanced to be 4.05% and 12.17 cd A–1 by optimizing the Cl amount, respectively. The positive effects of the Mg doping and Cl-passivation on the cadmium-free QD-LEDs are primarily ascribed to the reduced electron injection barrier of ETL/the emitting layer interface and slower electron mobility, which can be verified by the ultraviolet photoelectron spectroscopy (UPS) measurements and current density–voltage characteristics of electron-only devices.

Ternary AgInS2 and quaternary Ag–In–Zn–S nanocrystals, which could be partially exchanged with either In3+ or Zn2+ ions, were synthesized by using a seeded-mediated growth method.

A series of multinary Cu‐In‐Zn‐Se‐S nanocrystals (NCs) are synthesized via a phosphine‐free and one‐pot approach, in which the Se powder and 1‐dodecanethiol (DDT) are used as chalcogenide sources, respectively. The X‐ray photoelectron spectra are used to confirm the presence of lattice sulfur in the as‐obtained products. The emission color and the relative photoluminescence quantum yields of the Cu‐In‐Zn‐Se‐S NCs can be tuned by varying the Cu contents, the amount of Se powder, as well as the DDT dosage. In addition, the formation process of the multinary Cu‐In‐Zn‐Se‐S NCs is different from that of quaternary Cu‐In‐Zn‐S NCs, which is dominated by the doping of Cu ions into the In‐deficient In‐Zn‐Se‐S NCs but not the partial interdiffusion of Zn2+ into the Cu‐based NCs. This plausible deduction is based on the comparison of optical properties of the products synthesized using the hot‐injection and one‐pot methods. Furthermore, the performance of the solution‐processed quantum‐dot light‐emitting diodes (QLEDs) using the Cu‐In‐Zn‐Se‐S NCs as emission layers is examined, and the QLEDs exhibit a high luminance over 1500 cd m−2 and a high peak current efficiency of ≈0.4 cd A−1 at 1000 cd m−2.

Multinary copper chalcogenide semiconductor nanocrystals (NCs) have achieved increased attention due to their lessened toxicity and compositional versatility as well as their outstanding optical properties and optoelectronic applications in light‐emitting diodes (LEDs) and solar cells. Herein, the synthesis of highly luminescent multinary Cu‐In‐Zn‐S semiconductor NCs with tailored nanostructures, which exhibit the best absolute photoluminescence quantum yield of 90%, is presented. The tailored nanostructures are realized through the variation of the dosage and injection speed of Zn precursors, which determine the balance between Zn2+ cation diffusion and ZnS shelling reaction. The depth profile measured using X‐ray photoelectron spectroscopy reveals the gradient distribution of Zn elements from core to surface in the samples synthesized using higher feeding amounts of Zn precursors in a one‐pot method, which favors the formation of a soft core/shell structure. Time‐resolved spectroscopic studies confirm that the inward diffusion of Zn2+ and overcoating of a ZnS shell could reduce the number of intrinsic internal or surface defects, finally inducing a near‐unity radiative decay of excitons in single recombination pathway. As a demonstration, the highly luminescent multinary Cu‐In‐Zn‐S semiconductor NCs are incorporated into LEDs and a white light‐emitting diode is accessed through a two‐component strategy.

A review of recent advances in the improvement of quatum-dot light-emitting diodes through the nanostructure engineering of quantum dots and device architecture optimization.

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Ultrastrong coupling in the near-UV range between aluminum metal–insulator–metal cavities and CdZnS/ZnS quantum dots is revealed by using cathodoluminescence; at the same time, the plexcitonic modes are spatially mapped at the deep-subwavelength scale.

Using cathodoluminescence, the plasmonic modes of open triangle cavities patterned in single-crystal bulk aluminum are explored in deep subwavelengths from the UV to the visible, showing large Q factors.