Carbon-Dot-Assisted Room-Temperature Crystallization of Quasi-Two-Dimensional Perovskite Emitting Layers for Annealing-Free Light-Emitting Diodes.

The development of high-performance perovskite light-emitting diodes (PeLEDs) typically requires thermal annealing to optimize the crystallization and film quality. However, this energy-intensive process limits the scalability and environmental sustainability of perovskite-based devices. Here, we demonstrate a novel approach to fabricating high-quality perovskite emitting layers without the need for annealing, utilizing carbon dots (CDs) as an interface layer. The CDs, functionalized with abundant potassium ions, carboxylate, and amino groups, serve as nucleation centers and enhance precursor interactions. This facilitates room-temperature perovskite crystallization by lowering the formation energy, guiding uniform crystal growth, and improving the overall quality of the perovskite layer. Consequently, annealing-free PeLEDs demonstrate superior performance with a maximum external quantum efficiency of 20.5%, and large-area PeLEDs (225 mm) exhibit a high efficiency of 16.6%. This strategy not only eliminates the need for thermal processing but also enhances the electroluminescent performance, offering a scalable, low-cost, and energy-efficient pathway for fabricating high-performance perovskite-based optoelectronic devices.