A soft-chemistry route to prepare halide perovskite nanocrystals with tunable emission and high optical performance

Abstract

Cesium lead halide perovskites constitute a benchmark family of inorganic perovskites for high performance optoelectronic devices. Hot injection is by far the most extended procedure to fabricate CsPbX3 (X: Cl, Br, and/or I) perovskite nanocrystals (PNCs) of high quality. However, the tedious N2-vacuum cycles and fast heating/cooling steps hinder the large-scale production of these materials. This work presents a fast one-step methodology to fabricate small CsPb(ClxBr1-x)3 nanocrystals with good control of the particle size and shape by using a Soft Chemistry strategy (ligand-mediated controlled growth) and microwave heating. We demonstrate that the procedure can be extended to different mixed halide perovskites, thus providing a fine tuning of the chemical composition and consequently, tunable photoluminescence (PL) emission from 522 nm for pure CsPbBr3 to 477 nm for CsPb(Cl0.4Br0.6)3, high photoluminescence quantum yield (PLQY) up to ~86% (for CsPbBr3) and narrow PL full width at half maximum ~18–26 nm. In addition, the protocol was designed in such a way that the chemistry involved in the crystal nucleation and growth of perovskites is as close as possible to that of the hot injection process, which is mechanistically well-understood, to facilitate their adoption by the perovskite research community.