Size-tunable and efficient fabrication of CsPbBr₃ superlattices by high-temperature self-assembly for...

Superfluorescence in self-assembled CsPbBr₃ superlattices of colloidal quantum dots (QDs) has garnered extensive attention due to its ultra-fast, intense burst emission. Among the available fabrication methods for superlattices, saturated solvent evaporation remains widely utilized for its operational simplicity and cost-effectiveness. However, this conventional method exhibits poor controllability and process randomness owing to the absence of a stable preparation platform, thereby hindering controlled self-assembly. Here, a high-temperature (30-70 °C) saturated solvent evaporation method was developed for size-tunable and efficient preparation of high-quality CsPbBr₃ superlattices. In this approach, the coffee-ring effect governs assembly by driving solute transport, inducing a distinct spatial gradient where superlattice size decreases from the substrate edge to center. Systematic modulation of assembly temperature and QD concentration enables adjustability of superlattice dimensions. Specifically, higher temperatures attenuate solute migration, thereby reducing superlattice size, while increased QD concentration strengthens inter-dot interactions to promote the formation of larger superlattices. A near-100-fold radiative acceleration of the prepared superlattices compared to conventional QD films demonstrates the ultrafast superfluorescence emission capability. Combined with their potential for scalable production, a material foundation was provided for ultrafast photonic applications. And it also opens up a reliable pathway for superlattice fabrication, laying a foundation for future size-dependent superlattice research and the development of high-performance optoelectronic devices.