All-Perovskite Multicomponent Nanocrystal Superlattices

Abstract

Nanocrystal superlattices (NC SLs) have long been sought as promising metamaterials, with nanoscale-engineered properties arising from collective and synergistic effects among the constituent building blocks. Lead halide perovskite (LHP) NCs come across as outstanding candidates for SL design, as they demonstrate collective light emission, known as superfluorescence, in single- and multicomponent SLs. Thus far, LHP NCs have only been assembled in single-component SLs or coassembled with dielectric NC building blocks acting solely as spacers between luminescent NCs. Here, we report the formation of multicomponent LHP NC-only SLs, i.e., using only $CsPbBr_3$ NCs of different sizes as building blocks. The structural diversity of the obtained SLs encompasses the $ABO_6, ABO_3$, and NaCl structure types, all of which contain orientationally and positionally locked NCs. For the selected model system, the $ABO_6-type SL$, we observed efficient NC coupling and Förster-like energy transfer from strongly confined 5.3 nm $CsPbBr_3$ NCs to weakly confined 17.6 nm $CsPbBr_3$ NCs, along with characteristic superfluorescence features at cryogenic temperatures. Spatiotemporal exciton dynamics measurements reveal that binary SLs exhibit enhanced exciton diffusivity compared to single-component NC assemblies across the entire temperature range (from 5 to 298 K). The observed coherent and incoherent NC coupling and controllable excitonic transport within the solid NC SLs hold promise for applications in quantum optoelectronic devices.