Abstract
Topotactic anion exchange has been developed to tune the composition and band gap energies of cesium lead halide (CsPbX3) perovskite nanocrystals (NCs). However, current anion exchange methods either require harsh conditions or take a long time to realize substantial substitution. Here, we present a method to modulate the composition of colloidal CsPbBr3 NCs through ultrasonication-assisted anion exchange with CsX (X = Cl, I) solution. Efficient anion exchange of CsPbBr3 NCs with Cl− or I− is realized with substitution ratio up to 93% and preservation of the pristine shape and structure of CsPbBr3 NCs. This anion exchange results in tunable emission, covering the whole visible spectral range, with relatively high photoluminescence quantum yield, narrow emission bandwidths, and good stability. This work provides a facile and efficient way to engineer the properties of halide perovskite NCs and has great potential for large-scale production of compositionally diverse perovskite NCs.
Highlights
All-inorganic CsPbX3 (X=Cl, Br, and I) perovskite nanocrystals (NCs) have gained significant attention owing to their high photoluminescence (PL) quantum yield (QY) [1], narrow emission line width [2], defect tolerance [3, 4], and wide range of band gaps tunable by control of both composition [5, 6] and morphology [7–9]
The presynthesized CsPbBr3 NCs are dispersed in hexane, and the anion exchange is realized through the interfacial reaction with CsX (X=Cl, I) aqueous solution assisted by ultrasonication
0.8 g of Cs2CO3(99.9%, Aldrich), 2.5 ml of oleic acid (OA; 90%, Aldrich) and 30 ml of octadecene (ODE; 90%, Aldrich) are added into a 100-ml 3-neck flask, degassed at room temperature for 30 min, and dried for 1 h at 120 °C under Ar until all Cs2CO3 reacted with OA. 0.136 g of PbBr2 (99.9%, Aldrich), 2 mL of oleylamine (OALM; Aldrich, 80–90%), 1.5 mL of OA, and 8 mL ODE are added to a 25-mL 3-neck round bottom flask
Summary
All-inorganic CsPbX3 (X=Cl, Br, and I) perovskite nanocrystals (NCs) have gained significant attention owing to their high photoluminescence (PL) quantum yield (QY) [1], narrow emission line width [2], defect tolerance [3, 4], and wide range of band gaps tunable by control of both composition [5, 6] and morphology [7–9]. Yin et al reported one efficient method to transform the nonluminescent Cs4PbX6 NCs into CsPbX3 NCs [28, 29] These presynthesized Cs4PbX6 NCs were dispersed in nonpolar hexane, and the excess CsX was stripped and dissolved into the water through the interfacial reaction, and further etching of resultant CsPbBr3 NCs was prohibited by the interface between water and nonpolar solvent. We propose one facile anion exchange method to tune the composition and optical properties of the CsPbBr3 NCs. The presynthesized CsPbBr3 NCs are dispersed in hexane, and the anion exchange is realized through the interfacial reaction with CsX (X=Cl, I) aqueous solution assisted by ultrasonication. By adjusting the reaction time or the CsX aqueous solution, complete tunable composition of CsPbX3 NCs and emission covering the full visible spectral range with narrow band widths can be achieved
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