Investigation on Photoluminescence of CsPb(Br,I)₃ Perovskite Nanocrystals by Comparison between Hot-Injection and Ion-Exchange Methods

Abstract

Changes in photoluminescence (PL) peak width and quantum yield (PLQY) with halide composition were compared for CsPb(Br1−x I x )3 nanocrystals (NCs) prepared by hot-injection and ion-exchange methods. The hot-injection method produced single-phase cubic CsPb(Br1−x I x )3 NCs for each iodide ratio. In contrast, a small amount of orthorhombic phase was observed at higher x for NCs prepared by the ion-exchange methods. The PL peak width of mixed-halide NCs at x = 0.55 was broader than those of CsPbBr3 and CsPbI3, possibly as a result of compositional inhomogeneity among the individual NCs. However, the maximum PL peak width occurred at larger x for the ion-exchange methods, possibly because of partial transition to orthorhombic phase from cubic phase for CsPb(Br1−x I x )3 NCs. The minimum PLQY for the hot-injection method was 25.0% at x = 0.50, which was lower than the PLQYs of CsPbBr3 and CsPbI3 NCs (∼70%). In contrast, the minimum PLQY for the ion-exchange methods occurred at x = ∼0.3. Furthermore, the minimum PLQY was ∼10%, which was lower than 25.0% for the hot-injection method. The addition of halide solution for ion exchange might affect the adsorption state of surface modifiers, leading to the decreased PLQY.

Improving the thermal resistance of fluorescent CsPb(Br,I) 3 perovskite quantum dots by surface modification with perfluorodecanoic acid

“…Instead, desired PL properties are realized by precisely tuning the composition of mixed-halide QDs. I-doped CsPbBr 3 QDs (typically represented by the label CsPb(Br,I) 3 QDs) realize green emission, the colour of which is very close to the vertex of chromaticity coordinate in the Rec.2020 standard for wide-colour-gamut displays [13,37]. However, mixed-halide QDs can be subject to partial decomposition and/or dissolution, changing the halide compositional ratio and thus leading to shifts in their absorption and emission wavelengths.…”

Effects of Perfluorodecanoic Acid on the Photostability and Self-Recovery of Cesium Lead Bromide Nanocrystals

“…[1][2][3][4][5][6][7] For instance, they exhibit high photoluminescence (PL) quantum yields of up to 90%, and their emission color can be tuned over the entire visible region depending on their size and halide composition. 8,9 As synthesized perovskite NCs show cubic morphologies with narrow particle-size distributions; therefore, their dispersions exhibit sharp PL peaks. 10 Furthermore, they have attracted extensive research attention because of their higher stability to external environments compared with organic-inorganic hybrid perovskite NCs commonly used in the photovoltaic field.…”