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Nickel oxide (NiOx) serves as one of the most promising hole transport materials for perovskite light‐emitting diodes (PeLEDs). However, only moderate PeLED performances have been reported on the pristine NiOx layer due to insufficient hole injection, interfacial exciton quenching, and poor perovskite quality. Herein, a multifunctional molecule of 3‐mercapto‐1‐propanesulfonate (MPS) is demonstrated to successfully tailor the NiOx–perovskite heterogenous interface by addressing the above issues. In detail, the large binding energy between mercapto sulfur and nickel induces preferential self‐assembly of the mercapto group on the NiOx surface, which simultaneously enlarges the NiOx work function by the formation of interfacial dipole and suppresses the trap‐assisted exciton quenching by the passivation of the oxygen vacancies. Meanwhile, the self‐assembled MPS on NiOx also favors high‐quality perovskite films with good morphology, high crystallinity, and reduced defects for efficient carrier radiative recombination. As a result, blue PeLEDs show a remarkable efficiency of 10.4%, representing one of the highest efficiencies for NiOx‐based blue PeLEDs, as well as a very low turn‐on voltage of 2.8 V. Consequently, this work contributes to an efficient approach to tailor the NiOx–perovskite interface for highly efficient blue PeLEDs. [ABSTRACT FROM AUTHOR]

Despite the substantial progress in sky‐blue (480−495 nm) perovskite light‐emitting diodes (PeLEDs), the pure‐blue PeLEDs (<480 nm) merely show moderate performances. As a straightforward and effective facile way to obtain pure‐blue emission, the bromide‐chloride mixed perovskites have received considerable attention. However, the tricky issue of halide migration in the mixed halide perovskites makes a tough challenge to achieve efficient PeLEDs with stable electroluminescence (EL) spectra. Herein, the in situ treatment of Cl‐rich benzene phosphorus oxydichloride (BPOD) is proposed to achieve high‐quality pure‐blue perovskites by simultaneously enlarging the perovskite bandgap, passivating the halide vacancy defects, and immobilizing the halide ions through the hydrolysis products of chloride ions and phenylphosphonic acid. As a result, highly‐performed pure‐blue PeLEDs with a maximum external quantum efficiency (EQE) of 9.3% at 477 nm, an impressive lifetime of 34.7 min at 104 cd m−2, and very stable EL spectra are achieved, which are superior to the conventional mixed halide PeLEDs based on lead‐chloride precursor, representing one of the best performances for mixed halide pure‐blue PeLEDs. Therefore, this work contributes a feasible and effective method for efficient and stable pure‐blue PeLEDs. [ABSTRACT FROM AUTHOR]

ZnO nanoparticles (NPs) and their derivatives are the most commonly used electron transport materials for quantum dot light‐emitting diodes (QLEDs). However, their ubiquitous issues of severe exciton quenching and poor shelf stability render a limited application in practical use. Herein, the mercaptopropionic acid (MPA)‐capped ZnMgO (MPA‐ZMO) NPs with good optoelectronic properties are proposed to address these problems for efficient and stable QLEDs. The massive oxygen vacancy defects at the ZMO NP surface are effectively passivated by MPA, which inhibits the defect‐associated exciton quenching for bright emission. Besides, an improvement in electron mobility and an upward energy band is also achieved for MPA‐capped ZMO NPs, enabling good carrier injection and transportation. The superior optoelectronic properties contribute great enhancements of the device performances with over 30% increase in external quantum efficiency (EQE) from 16.5 to 21.6% and over 2.5‐fold improvement in a lifetime from 2636.41 to 6601.29 h at 1000 cd m−2, together with the impressive QLED shelf stability of less than 5% variation in device efficiency during 3‐week storage, showing one of the best performances among currently reported ZMO‐based QLEDs. Consequently, this work contributes an effective approach to decorating the inorganic metal oxide NPs for efficient and stable QLEDs. [ABSTRACT FROM AUTHOR]

Metal halide perovskite nanocrystals (NCs) have emerged as an alternative to conventional phosphors for wide color gamut displays. However, the issues of poor stability and low emission efficiency of pure‐red CsPbBrxI3‐x NCs set an obstacle to their practical application. Herein, the synergistic effect of Mn doping and mesoporous SiO2 sealing is reported through in situ formation of Mn‐doped NCs into mesoporous SiO2 nanospheres (MnNCs@SiO2) to structurally and spatially stabilize the perovskite NCs for bright and stable pure‐red emitter. The large bonding energy of Mn‐halogen effectively suppresses the halide vacancy defects, prompting the highest photoluminescence quantum yield (PLQY) up to 84% (634 nm) among the pure‐red composite analogs. More importantly, the nanocrystal structure stability is fundamentally improved by the enhanced formation energy with Mn doping, together with the spatial isolation by SiO2 nanospheres. The MnNCs@SiO2 films exhibit impressive stabilities against high‐temperature heating, thermal cycle test, UV irradiation, water, and acid/alkali erosion, representing one of the most stable pure‐red perovskite emitters. By integrating fabricated all‐perovskite CsPbX3 single color conversion film into the liquid crystal display (LCD) modules, a wide color gamut of 128% of NTSC is achieved, enabling an excellent color rendition for high‐saturation object colors toward practical applications. [ABSTRACT FROM AUTHOR]

As an alternative electron transport material to the chemically unstable ZnO nanoparticles (NPs), SnO2 NPs exhibit a great potential to construct high‐performance quantum dot light‐emitting diodes (QLEDs). However, only moderate device performance has been obtained for SnO2‐based QLEDs due to the low electron mobility, unfavorable energy band, and massive defects of SnO2 NPs. Herein, a strategy of transition metal doping is reported to achieve high‐quality manganese‐doped SnO2 (Mn‐SnO2) NPs to address the above problems. Specifically, the large bond energy of Mn─O bonds reduces the oxygen vacancy defects, prompting an effective suppression of the interfacial exciton quenching for massive radiative recombination. Moreover, the favorable energy band and high electron mobility for Mn‐SnO2 promote efficient electron injection and transportation. The good optoelectronic properties for Mn‐SnO2 NPs contribute to a great enhancement in device efficiency from 8.2 to 11.4% and a remarkable improvement in lifetime (T95) from 565.3 to 1009.2 h at 1000 cd−2, among the best performing ZnO‐free QLEDs. Notably, the Mn‐SnO2 based QLEDs show a very superior shelf stability to the QLEDs based on SnO2 and ZnO analogs. Consequently, this work reports an effective approach to achieve high‐quality SnO2 NPs for efficient and stable QLEDs. [ABSTRACT FROM AUTHOR]

ZnSeTe quantum dots (QDs), as a promising environmentally friendly emitter, have been extensively studied for blue quantum dot light-emitting diodes (QLEDs). Although numerous reports have focused on QD shell structures and surface treatments, very few reports have investigated ligand reaction byproducts, which also play an important role in QD surface decoration. Herein, we propose a strategy of chloroform post-treatment to improve QD optoelectronic properties. In detail, the Cl– byproduct produced through the reaction between chloroform and the tri-n-octylphosphine (TOP) ligand effectively passivates QD surface defects for enhanced radiative recombination and further removes the native oleic acid ligand for efficient charge transportation. Consequently, the photoluminescence quantum yield (PLQY) substantially improved from 39.6 to 92.0%, and the average QD lifetime increased from 37.1 to 65.2 ns, which promoted an over 3-fold improvement in the device efficiency from 0.62 to 2.25%. This work provides an effective method to tailor QD surface states for improved electroluminescence. [ABSTRACT FROM AUTHOR]

Multi‐shelled ZnSeTe/ZnSe/ZnS quantum dots (QDs) have served as a promising eco‐friendly emitter for blue quantum dot light‐emitting diodes (QLEDs). While extensive studies have concentrated on the optimization of the shell species and thickness of the multi‐shelled QDs to raise the QLED electroluminescent performance, very few reports focus on the QD surface states involving ligand and defect modulations which are essential for high‐performance QLEDs. Herein, the strategy of bromide decoration is theoretically and practically demonstrated to simultaneously diminish the QD surface defects by passivating the unsaturated Zn for strengthened carrier radiative recombination and removing the superabundant oleic acid through ligand exchange for efficient carrier transport. As a result, the merits of bromide decoration benefit a large increase in photoluminescence quantum yield (PLQY) from 39.7% to 86.2% at the wavelength of 443 nm, as well as a great enhancement of the device performance with over sevenfold improvement in external quantum efficiency (EQE) from 0.74% to 5.46% and a distinct decrease in turn‐on voltage from 6.7 to 5.9 V. Consequently, this work contributes an effective approach of the multi‐shelled QD surface decoration toward enhanced QLED performance. [ABSTRACT FROM AUTHOR]