Although perovskite light-emitting diodes (PeLEDs) have recently experienced significant progress, there are only scattered reports of PeLEDs with both high efficiency and long operational stability, calling for additional strategies to address this challenge. Here, we develop perovskite-molecule composite thin films for efficient and stable PeLEDs. The perovskite-molecule composite thin films consist of in-situ formed high-quality perovskite nanocrystals embedded in the electron-transport molecular matrix, which controls nucleation process of perovskites, leading to PeLEDs with a peak external quantum efficiency of 17.3% and half-lifetime of approximately 100 h. In addition, we find that the device degradation mechanism at high driving voltages is different from that at low driving voltages. This work provides an effective strategy and deep understanding for achieving efficient and stable PeLEDs from both material and device perspectives.

It is widely acknowledged that constructing small injection barriers for balanced electron and hole injections is essential for light-emitting diodes (LEDs). However, in highly efficient LEDs based on metal halide perovskites, a seemingly large hole injection barrier is usually observed. Here we rationalize this high efficiency through a surfactant-induced effect where the hole concentration at the perovskite surface is enhanced to enable sufficient bimolecular recombination pathways with injected electrons. This effect originates from the additive engineering and is verified by a series of optical and electrical measurements. In addition, surfactant additives that induce an increased hole concentration also significantly improve the luminescence yield, an important parameter for the efficient operation of perovskite LEDs. Our results not only provide rational design rules to fabricate high-efficiency perovskite LEDs but also present new insights to benefit the design of other perovskite optoelectronic devices.

Chiral metal halides are promising materials for nonlinear optics and spin-selective devices. Typically, chirality is introduced via large chiral organic cations, leading to low-dimensional structures and limitations in charge transport. Here, we design a family of chiral metal halides based on the relatively small ditopic R/S-3-aminoquinuclidine (3-AQ) cation, forming an (R/S-3AQ)-Pb₂Br₆ structure closely related to the 3D corner-sharing octahedral network of perovskites. The resulting material exhibits a direct bandgap, isotropic band structure, and fully 3D photoexcitation. Circular dichroism confirms a chiral anisotropy factor consistent with theoretical predictions. Moreover, the material displays a Rashba effect in the conduction band, which is attributed to spin-orbit coupling and the lack of inversion symmetry. Offering rich chemical tunability and efficient 3D charge transport, this new class of chiral semiconductors provides a promising platform for advancing nonlinear optoelectronic and spintronic devices.

Tin-halide perovskites are emerging as exceptional materials for near-infrared light-emitting diodes (NIR-LEDs). However, their extreme oxygen sensitivity remains a significant obstacle to practical applications. This work presents a facile yet effective strategy to overcome this limitation by designing self-encapsulated tin-halide perovskite films. Incorporating a rational molecule, 4,4′-diaminodiphenyl sulfone, into precursors, it forms isolated tin-iodide perovskite particles that are encapsulated in situ, achieving outstanding air stability. The resulting films show high crystallinity, reduced trap density, and mitigated p-doping density, boosting radiative charge recombination to reach an impressive photoluminescence quantum yield approaching 50%. Leveraging these advancements, the resulting NIR-LEDs demonstrate a record-breaking peak external quantum efficiency of 12.4%, accompanied by a substantial improvement in operational lifetime. Notably, for the first time, we demonstrated a functional tin-iodide perovskite-based device in ambient air. This work provides a robust pathway for realizing high-performance and stable tin-halide perovskite-based optoelectronic devices, addressing critical challenges for their widespread application.