Pure‐red perovskite LEDs (PeLEDs) based on CsPb(Br/I)3 nanocrystals (NCs) usually suffer from a compromise in emission efficiency and spectral stability on account of the surface halide vacancies‐induced nonradiative recombination loss, halide phase segregation, and self‐doping effect. Herein, a “halide‐equivalent” anion of benzenesulfonate (BS–) is introduced into CsPb(Br/I)3 NCs as multifunctional additive to simultaneously address the above challenging issues. Joint experiment‐theory characterizations reveal that the BS– can not only passivate the uncoordinated Pb2+‐related defects at the surface of NCs, but also increase the formation energy of halide vacancies. Moreover, because of the strong electron‐withdrawing property of sulfonate group, electrons are expected to transfer from the CsPb(Br/I)3 NC to BS– for reducing the self‐doping effect and altering the n‐type behavior of CsPb(Br/I)3 NCs to near ambipolarity. Eventually, synergistic boost in device performance is achieved for pure‐red PeLEDs with CIE coordinates of (0.70, 0.30) and a champion external quantum efficiency of 23.5%, which is one of the best value among the ever‐reported red PeLEDs approaching to the Rec. 2020 red primary color. Moreover, the BS–‐modified PeLED exhibits negligible wavelength shift under different operating voltages. This strategy paves an efficient way for improving the efficiency and stability of pure‐red PeLEDs.

We study the solitons in parity-time symmetric potential in the medium with spatially modulated nonlocal nonlinearity. It is found that the coefficient of the spatially modulated nonlinearity and the degree of the uniform nonlocality can profoundly affect the stability of solitons. There exist stable solitons in low-power region, and unstable solitons in high-power region. In the unstable cases, the solitons exhibit jump from the original site to the next one, and they can continue the motion into the other lattices. The region of the stable soliton can be expanded by increasing the coefficient of the modulated nonlocality. Finally, critical amplitude of the imaginary part of the linear PT lattices is obtained, above which solitons are unstable and decay immediately.

Although tremendous progress has recently been made in quasi‐2D perovskite light‐emitting diodes (PeLEDs), the performance of red PeLEDs emitting at ≈650–660 nm, which have wide prospects for application in photodynamic therapy, is still limited by an inefficient energy transfer process between the quasi‐2D perovskite layers. Herein, a symmetric molecule of 3,3′‐(9H‐fluorene‐9,9‐diyl)dipropanamide (FDPA) is designed and developed with two functional acylamino groups and incorporated into the quasi‐2D perovskites as the additive for achieving high‐performance red PeLEDs. It is demonstrated that the agent can simultaneously diminish the van der Waals gaps between individual perovskite layers and passivate uncoordinated Pb2+ related defects at the surface and grain boundaries of the quasi‐2D perovskites, which truly results in an efficient energy transfer in the quasi‐2D perovskite films. Consequently, the red PeLEDs emitting at 653 nm with a peak external quantum efficiency of 18.5% and a maximum luminance of 2545 cd m−2 are achieved, which is among the best performing red quasi‐2D PeLEDs emitting at ≈650–660 nm. This work opens a way to further improve the electroluminescence performance of red PeLEDs.

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We numerically show the generation of robust vortex clusters embedded in a two-dimensional beam propagating in a dissipative medium described by the generic cubic-quintic complex Ginzburg-Landau equation with an inhomogeneous effective diffusion term, which is asymmetrical in the two transverse directions and periodically modulated in the longitudinal direction. We show the generation of stable optical vortex clusters for different values of the winding number (topological charge) of the input optical beam. We have found that the number of individual vortex solitons that form the robust vortex cluster is equal to the winding number of the input beam. We have obtained the relationships between the amplitudes and oscillation periods of the inhomogeneous effective diffusion and the cubic gain and diffusion (viscosity) parameters, which depict the regions of existence and stability of vortex clusters. The obtained results offer a method to form robust vortex clusters embedded in two-dimensional optical beams, and we envisage potential applications in the area of structured light.