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.

The morphological features of the active layer has always been an important factor limiting the efficiency of organic solar cells (OSCs). Although halogen‐based additives capable of forming non‐covalent bonds with active molecules can effectively adjust the morphology of active layer, the inner mechanism of positional isomerization of additives on the crystallization kinetics of bulk heterojunction has been ignored, which hinders further development of this technique. Herein, a new additive‐assisted optimization strategy for high‐efficiency OSCs based on three positional isomeric additives is proposed, which have different sites for two bromine substituents on the benzene ring. The results demonstrate that symmetrically structured additives with the smallest dipole moment, the lowest steric hindrance and the most uniformly distributed electrostatic potential, can form more suitable non‐covalent interactions with the acceptor, resulting in more reasonable molecular spatial distribution and better π–π stacking behavior. For other non‐fullerene systems, the symmetrically structured additive also shows the best effect on optimizing molecular aggregation and stacking. This work provides guidance for screening and designing additives with excellent morphology improvement capability and is expected to have a profound influence on further increasing efficiency of OSCs without adopting the isomerization strategy for active molecules possessing complex conjugated backbones and branched chains.

Organic memristors are considered to be the next-generation storage element due to their unique advantages of flexibility, transparency, and good solution processability. In this Letter, a Zn-porphyrin based small-molecular organic memristor is prepared by spin-coating with an ultralow resistive switching set voltage of 0.38 V. It is found that the zinc atom in the porphyrin molecule plays a very important role in improving the resistance switching characteristics of organic memristors. By tracking the change in oxygen valence in the vertical dimension, we demonstrate that Zn atom located in the core of porphyrin helps to enhance the oxygen ion migration across the active layer, clearly revealing the memory mechanism of low-cost solution-processed Zn-porphyrin based small-molecular organic memristors. This organic memristor shows excellent memristive performance resulting from rational material design and appropriate device structure engineering.

The 2D Ruddlesden–Popper perovskites (RPPs), consisting of alternating organic spacer layers and inorganic layers, are emerging photovoltaic materials because of their highly tunable optoelectronic properties and improved stability compared to their 3D counterparts. Nonhalide lead sources attract increasing attention in 3D perovskites, whereas the lead sources for RPPs are limited to lead halides. Herein, nonhalide lead source of lead acetate is investigated for high‐quality RPP films by a dimethyl sulfoxide (DMSO)‐assisted delayed annealing process. The incorporation of DMSO in the lead acetate–based precursor solution regulates the crystallization process, resulting in RPP films with distinctly enhanced crystallinity, reduced trap density, vertical crystal orientation, and graded phase distribution. Consequently, the optimized RPP solar cell with an inverted planar structure delivers a champion power conversion efficiency of 17.3%. Herein, future developments of nonhalide lead sources are spurred to fabricate RPP films with high device performance.