Universal Molecular Control Strategy for Scalable Fabrication of Perovskite Light-Emitting Diodes.

Despite the rapid progress in perovskite light-emitting diodes (PeLEDs), the electroluminescence performance of large-area perovskite devices lags far behind that of laboratory-size ones. Here, we report a 3.5 cm × 3.

Mixed-Dimensional MXene-Based Composite Electrodes Enable Mechanically Stable and Efficient Flexible Perovskite Light-Emitting Diodes.

Significant advancements in perovskite light-emitting diodes (PeLEDs) based on ITO glass substrates have been realized in recent years, yet the overall performance of flexible devices still lags far behind, mainly being ascribed to the high surface roughness and poor optoelectronic properties of flexible electrodes. Here, we report efficient and robust flexible PeLEDs based on a mixed-dimensional (0D-1D-2D-3D) composite electrode consisting of 0D Ag nanoparticles (AgNPs)/1D Ag nanowires (AgNWs)/2D MXene/3D poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). Our designed MXene-based electrodes combine the advantages of facile formation of a film of low-dimensional materials and excellent optical and electrical properties of metal, inorganic, and organic semiconductors, which endow the electrodes with high electrical/thermal conductivity, flexibility, a smooth surface, and good transmittance.

Smoothing the energy transfer pathway in quasi-2D perovskite films using methanesulfonate leads to highly efficient light-emitting devices.

Quasi-two-dimensional (quasi-2D) Ruddlesden-Popper (RP) perovskites such as BACsPbBr (BA = butylammonium, n > 1) are promising emitters, but their electroluminescence performance is limited by a severe non-radiative recombination during the energy transfer process. Here, we make use of methanesulfonate (MeS) that can interact with the spacer BA cations via strong hydrogen bonding interaction to reconstruct the quasi-2D perovskite structure, which increases the energy acceptor-to-donor ratio and enhances the energy transfer in perovskite films, thus improving the light emission efficiency. MeS additives also lower the defect density in RP perovskites, which is due to the elimination of uncoordinated Pb by the electron-rich Lewis base MeS and the weakened adsorbate blocking effect.

Boosting the Efficiency of NiO-Based Perovskite Light-Emitting Diodes by Interface Engineering.

Nickel oxide (NiO) is a promising hole-transporting material for perovskite light-emitting diodes (PeLEDs) because of its low cost, excellent stability, and simple fabrication process. However, the electroluminescence efficiencies of NiO-based PeLEDs are greatly limited by inefficient hole injection and exciton quenching at the NiO-perovskite interfaces. Here, a novel interfacial engineering method with sodium dodecyl sulfate-oxygen plasma (SDS-OP) is demonstrated to simultaneously overcome the aforementioned issues.

Improving Efficiency and Stability in Quasi-2D Perovskite Light-Emitting Diodes by a Multifunctional LiF Interlayer.

Owing to the enlarged exciton binding energy and the ability to confine charge carriers compared to their three-dimensional (3D) counterparts, research on quasi-two-dimensional (quasi-2D) perovskite materials and the correlative application in light-emitting diodes (LEDs) has attracted considerable attention. However, high density of defects, exciton emission trapping, and unbalanced charge injection are still the main intractable obstacles to their further development and practical application. Herein, we report an efficient multifunctional interlayer, lithium fluoride (LiF), to boost the performance of green-emitting quasi-2D perovskite LEDs (PeLEDs) by simultaneously overcoming the aforementioned issues.