ZnO-based electron-transporting layers (ETLs) have been universally used in quantum-dot light-emitting diodes (QLEDs) for high performance. The active surface chemistry of ZnO nanoparticles (NPs), however, leads to QLEDs with positive aging and unacceptably poor shelf stability. SnO 2 is a promising candidate for ETLs with less reactivity, but NP agglomeration in nonionic solvents makes the conventional device structure abandoned, resulting in QLEDs with extremely low operational lifetimes. The large barrier for electron injection also limits the electroluminescence efficiency. Here, we report one solution to all the above-mentioned problems. Owing to the strong HO−SnO 2 coordination and the steric effect provided by the hydrocarbon groups, tetramethylammonium hydroxide can stabilize SnO 2 NPs in alcohol, while its intrinsic dipole induces a favorable electronic-level shift for charge injection. The SnO 2 -based devices, with the conventional structure, exhibit not only the most efficient electroluminescence among ZnO-free QLEDs but also an operational lifetime (T 95 ) over 3200 h at 1000 cd m −2 , which is comparable with that of state-of-the-art ZnO-based devices. More importantly, the superior shelf stability means that the TMAH−SnO 2 NPs are promising to enable QLEDs with real stability.

Metal halide perovskite quantum dots (QDs) and polymer composite films have witnessed extensive investigation in flexible optoelectronic devices, while the unsatisfactory environmental and mechanical properties of the composite films set substantial limitations for practical applications. Herein, highly luminescent perovskite QDs-polymer composite films (QPFs) are fabricated with remarkable environmental and mechanical stabilities by incorporation of perovskite QDs into fluoroelastomer polymeric matrix. The stretchable QPFs show excellent self-healing ability with micron-and centimeter-scale cracks healed in dozens of minutes and hours, respectively, due to the strong dipole-dipole interaction between the CF bonds of fluoroelastomer. After careful optimization of QDs ratios, a flat and smooth film morphology is achieved with a uniform distribution of QDs, which promotes good optical properties with a long PL lifetime of 1213.75 ns and high photoluminescence quantum yields up to 96.1%, and super environmental and mechanical stability These merits of QPFs enable their practical applications in flexible white light-emitting devices and wide color gamut displays with 124% of standard National Television Standards Committee and 96% of Recommendation 2020, respectively, exhibiting vivid pictures with high saturations for the object colors, indicating great potential toward practical applications.

perovskite has exhibited great potential to be an ideal luminescent material for perovskite light-emitting diodes (PeLEDs). However, the loworder phases (especially n = 1 phase) and the inevitable defects result in massive nonradiative recombination and poor emission efficiency. Herein, a multifunctional molecule of tetrabutylammonium dihydrogen phosphate (TDP) is introduced to simultaneously suppress the low-n phase, passivate the defects, and increase the exciton binding energy of the quasi-2D perovskite for massive radiative recombination and thus high emission efficiency. The multifunctional roles of TDP are realized by the synergistic effects of tetrabutylammonium cation and dihydrogen phosphate anion, both of which show strong interaction with the lead bromide octahedron of the perovskite. As a result, the TDP-incorporated perovskite films show a great enhancement of the emission efficiency with a remarkable increase in photoluminescence quantum yield (PLQY) from 34.6 to 96.9% at the wavelength of 522 nm. The strengthened radiative recombination promotes efficient emission efficiency with over 2.5-fold improvement in external quantum efficiency (EQE) and current efficiency (CE) from 3.27% and 10.83 cd A −1 to 9.25% and 28.35 cd A −1 , respectively, as well as high brightness with over 37% enhancement from 12713 to 17536 cd m −2 . Consequently, this work contributes to an efficient approach to employ a multifunctional molecule for highly emissive quasi-2D perovskites and enhanced quasi-2D PeLED performances.

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.

The shelf-stability issue, originating from the ZnO-induced positive aging effect, poses a significant challenge to industrializing the display technology based on solution-processed quantum-dot light-emitting diodes (QLEDs). Currently, none of the proposed solutions can simultaneously inhibit exciton quenching caused by the ZnO-based electron-transporting layer (ETL) and retain other advantages of ZnO. Here in this work, we propose a bilayer design of ETL in which a buffer layer assembled of SnO2 nanoparticles (NPs) suppresses the QD-ETL exciton quenching and tunes charge balance while ZnO NPs provide high electron conductivity. As a result, the bottom-emitting QLED combining capped ZnO and SnO2 buffer exhibit a maximum luminance over 100,000 cd m−2 and a T95 operational lifetime averaging 6200 h at 1000 cd m−2 on the premise of entirely inhibiting positive aging.