Moiré superlattices of two-dimensional copper nanocluster assemblies with tuneable twin emissions from hierarchical components leading to white light emission

Abstract

Chemically programmed angular stacking of two-dimensional (2D) assembly into interactive superstructures – such as moiré superlattices – may bring novel physical and chemical properties purely due to interlayer interactions. Herein, we report the formation of moiré superlattices through supramolecular chemical reaction of 2D crystalline copper nanocluster assemblies of hexagonal lattices with triphenylphosphine in the liquid medium, having an association constant of (5.8 ± 2.0) × 10⁴ M⁻¹. Transmission electron microscopic analysis confirmed the angles of twist of the nanosheets producing large moiré periodicity below 5°. The so-formed moiré superlattices with large periodicities generated a new quantum emissive state owing to the cuprophilic interactions amongst the neighbouring clusters of the adjacent layers. The retention of the red emission of the constituent 2D nanosheets and the tuneable new emission due to the now closely spaced clusters in the twisted super-stacking resulted in near white light photoluminescence. Moreover, the super-structures exhibited enhanced delayed photoluminescence with an increased lifetime that was on the order of 0.1 ms.