Synthesis of Cesium Lead Halide Perovskite Nanocrystals in a Droplet-Based Microfluidic Platform: Fast Parametric Space Mapping

Abstract

Prior to this work, fully inorganic nanocrystals of cesium lead halide perovskite (CsPbX3, X = Br, I, Cl and Cl/Br and Br/I mixed halide systems), exhibiting bright and tunable photoluminescence, have been synthesized using conventional batch (flask-based) reactions. Unfortunately, our understanding of the parameters governing the formation of these nanocrystals is still very limited due to extremely fast reaction kinetics and multiple variables involved in ion-metathesis-based synthesis of such multinary halide systems. Herein, we report the use of a droplet-based microfluidic platform for the synthesis of CsPbX3 nanocrystals. The combination of online photoluminescence and absorption measurements and the fast mixing of reagents within such a platform allows the rigorous and rapid mapping of the reaction parameters, including molar ratios of Cs, Pb, and halide precursors, reaction temperatures, and reaction times. This translates into enormous savings in reagent usage and screening times when compared to analogous batch synthetic approaches. The early-stage insight into the mechanism of nucleation of metal halide nanocrystals suggests similarities with multinary metal chalcogenide systems, albeit with much faster reaction kinetics in the case of halides. Furthermore, we show that microfluidics-optimized synthesis parameters are also directly transferrable to the conventional flask-based reaction.

Colloidal lead halide perovskite nanocrystals: synthesis, optical properties and applications

“…Later on, by means of a droplet-based microfluidic platform, allowing for online absorption/PL measurements, the same group explored the formation mechanism of these perovskite NCs. 61 Koolyk et al 62 investigated the growth process of caesium lead halide perovskite NCs by time-dependent TEM characterization. They found that the growth kinetics are different for CsPbBr 3 and CsPbI 3 , providing a model for each growth process.…”

Organic–inorganic metal halide hybrids beyond perovskites

“…For instance, all-inorganic CsPbX 3 nanocrystals are found to have much higher stability than organic metal halide perovskites MAPbX 3 , and exhibit narrow emissions with high PLQEs [69,70], which made them highly attractive for lasing and LEDs [34]. Tuning the photoluminescence of cesium lead halide perovskites could be realized by both compositional control and quantum size engineering [71,72]. It was demonstrated that by changing the capping organic ligand, the morphology of CsPbX 3 could be effectively tuned from nanocubes to nanowires and nanoplatelets with different sizes (Figure 4) [73][74][75].…”

All-Inorganic Perovskite CsPb2Br5 Microsheets for Photodetector Application

“…To date, all-inorganic cesium lead halide perovskite have generated considerable attention because of their higher stability and outstanding optoelectronic properties comparable to the hybrid organic-inorganic perovskites [17][18][19][20]. Thus, a large number of CsPbX 3 (X = I, Br, Cl) perovskite nanostructures such as nanocrystals [21], nanowires [22], microsheets [23,24], nanocubes, were prepared by solution processing approach. Furthermore, the physical properties of all-inorganic nanocrystals could be adjusted by their geometric shape and size [25].…”