Low-dimensional organometallic halide perovskites are actively studied for the light-emitting applications due to their properties such as solution processability, high luminescence quantum yield, large exciton binding energy, and tunable band gap. Introduction of large-group ammonium halides not only serves as a convenient and versatile method to obtain layered perovskites but also allows the exploitation of the energy-funneling process to achieve a high-efficiency light emission. Herein, we investigate the influence of the addition of ethylammonium bromide on the morphology, crystallite structure, and optical properties of the resultant perovskite materials and report that the phase transition from bulk to layered perovskite occurs in the presence of excess ethylammonium bromide. On the basis of this strategy, we report green perovskite light-emitting devices with the maximum external quantum efficiency of ca. 3% and power efficiency of 9.3 lm/W. Notably, blue layered perovskite light-emitting devices with the Commission Internationale de I'Eclairage coordinates of (0.16, 0.23) exhibit the maximum external quantum efficiency of 2.6% and power efficiency of 1 lm/W at 100 cd/m, representing a large improvement over the previously reported analogous devices.

Research on the incorporation of cutting-edge nano-antibacterial agent for designing dental materials with potent and long-lasting antibacterial property is demanding and provoking work. In this study, a novel resin-based dental material containing photocurable core-shell AgBr/cationic polymer nanocomposite (AgBr/BHPVP) was designed and developed. The shell of polymerizable cationic polymer not only provided non-releasing antibacterial capability for dental resins, but also had the potential to polymerize with other methacrylate monomers and prevented nanoparticles from aggregating in the resin matrix. As a result, incorporation of AgBr/BHPVP nanocomposites did not adversely affect the flexural strength and modulus but greatly increased the Vicker's hardness of resin disks. By continuing to release Ag ions without the impact of anaerobic environment, resins containing AgBr/BHPVP nanoparticles are particularly suitable to combat anaerobic cariogenic bacteria. By reason of the combined bactericidal effect of the contact-killing cationic polymers and the releasing-killing Ag ions, AgBr/BHPVP-containing resin disks had potent bactericidal activity against S. mutans. The long-lasting antibacterial activity was also achieved through the sustained release of Ag ions due to the core-shell structure of the nanocomposites. The results of macrophage cytotoxicity showed that the cell viability of dental resins loading less than 1.0 wt% AgBr/BHPVP was close to that of neat resins. The AgBr/BHPVP-containing dental resin with dual bactericidal capability and long term antimicrobial effect is a promising material aimed at preventing second caries and prolonging the longevity of resin composite restorations.

Modification of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) with sodium-poly(styrenesulfonate) leads to a ca. 0.3 eV increase in the work function and 15 times enhancement in the photoluminescence intensity of the overlying perovskite layer, which is closely correlated with the formation of a highly PSS-enriched top layer. As a direct result, the hybrid halide perovskite light-emitting devices with a modified PEDOT:PSS layer show the maximum external quantum efficiency of 7.2% and power efficiency of 19.0 lm W, which are 14-20 times those of the analogous devices using a pristine PEDOT:PSS layer and among the best reported values for the light-emitting devices using a neat perovskite emission layer. Our results illustrate that insufficient hole injection and luminescence quenching at the PEDOT:PSS anode are among the most important factors limiting the external quantum efficiencies of inverted perovskite light-emitting devices.

Although a variety of passivators have been researched to passivate the defects, sufficient defect passivation still remains a challenge to further elevate the efficiency of perovskite light emitting diodes (PeLEDs). Herein, we report that the BMIM + ions of the 1-butyl-3methylimidazolium tetrafluoroborate (BMIMBF 4 ) ionic liquid have effective passivation interaction to the Pb-related defects. And, the spontaneously formed targeted distribution of the BMIM + ions on the crystal surface and film top surface of the polycrystalline perovskite layers well matches the defect site distribution, resulting in the defects being sufficiently passivated. As a result, sufficient defect passivation of ionic liquid enables the photoluminescence quantum yields (PLQYs) to reach 100% and the maximum external quantum efficiency (EQE) of the PeLEDs increased to 22.9%. This work initializes the selection of the promising ionic liquid passivators for high efficiency PeLEDs and highlights the critical role of the passivator spatial distribution for sufficient defect passivation.