Fig. 1. (Color online) (a) The crystal structure of cubic CsPbX₃ NCs. Reproduced with permission from Ref. [24]. (b) Images of CsPbX₃ NCs dispersions with different emission colors under the UV light. Reproduced with permission from Ref. [26]. (c) The TEM image of CsPbBr₃ NCs with the cubic morphology. Reproduced with permission from Ref. [26]. (d) Absorption and PL spectra of CsPbX₃ NCs with different compositions. Reproduced with permission from Ref. [26].

Fig. 2. (Color online) (a) Schematic of the hot-injection method. The digital graph and TEM image of the corresponding sample are shown as insets. Reproduced with permission from Ref. [24]. (b) Schematic of the room temperature fabrication strategy. The digital graph of as prepared CsPbBr₃ NCs dispersion is presented aside. Reproduced with permission from Ref. [24]. (c) Schematic of the single-step tip ultrasonication synthesis. The digital images of as-prepared CsPbBr₃ and CdsPbI₃ NCs are shown as below. Reproduced with permission from Ref. [37].

Fig. 3. (Color online) (a) Flowchart of the template-assisted synthesis of CsPbX₃ NCs in the pores of mesoporous silica, and photographs of mesoporous silica impregnated with CsPbBr₃ (left) and CsPb(Br_0.25I_0.75)₃ NCs (right) under daylight and under UV illumination. Reproduced with permission from Ref. [40]. (b) Illustration of the droplet-based microfluidic platform integrated with online absorbance and fluorescence detection for the synthesis and real time characterization of CsPbX₃ NCs. Reproduced with permission from Ref. [43]. (c) Illustration of in-situ growth of all-inorganic CsPbX₃ nanocrystals in the polymers via one-step electrospinning technique. Reproduced with permission from Ref. [44]. (d) Schematic and photographs of mechano-synthesis of CsPbX₃ NCs and their fluorescence under UV light irradiation during ball milling. Reproduced with permission from Ref. [45].

Fig. 4. (Color online) Overview of the different anion-exchange routes and precursors within the cubic CsPbX₃ NCs and their corresponding XRD patterns reported by (a) Kovalenko group and (b) Manna group respectively. Reproduced with permission from Refs. [49, 50].

Fig. 5. (Color online) (a) Schematic diagram of the evolution process of Cs₄PbBr₆ to CsPbBr₃ NCs with addition of extra PbBr₂. Corresponding emission and PL spectra, XRD patterns and TEM images before and after the treatment are shown aside. Reproduced with permission from Ref. [62]. (b) Schematic illustration of of the transformation from Cs₄PbBr₆ to CsPbBr₃ NCs with stripping of CsBr. Below are photographs under daylight and UV light, showing the stability of CsPbBr₃ NCs obtained through hot-injection method (upper row) and water-triggered transformation process (bottom row). Top layer, CsPbBr₃ NCs dispersed in hexane; bottom layer, water. Reproduced with permission from Ref. [65]. (c) Illustration of Cs₄PbBr₆ to CsPbBr₃ NCs through the extraction of CsBr achieved either by thermal annealing (physical approach) or by chemical reaction with Prussian Blue (chemical approach). Reproduced with permission from Ref. [66]. (d) Illustration of ligand mediated transformation of pre-synthesized CsPbBr₃ to Cs₄PbBr₆ NCs initiated by amine addition. Reproduced with permission from Ref. [63]. (e) Schematic of the ligand control of the dynamic reversibility between CsPbBr₃ and Cs₄PbBr₆ NCs. On the left are TEM images of cubic CsPbBr₃ to Cs₄PbBr₆ NCs from left to right, and on the right are two complete CsPbBr₃ to Cs₄PbBr₆ NCs cycles by ultraviolet−visible spectroscopy. Reproduced with permission from Ref. [69].

Fig. 6. (Color online) (a) Schematic illustration of the transformation from CsPbBr₃ to CsPb₂Br₅ NCs induced by alkyl-thiols, with controlled morphologies by tuning the ratios of alkyl-thiols to amines and acids. Reproduced with permission from Ref. [70]. (b) Schematic diagram of reversible light-induced structural transitions from orthorhombic CsPbBr₃ to tetragonal CsPb₂Br₅ nanosheets. Reproduced with permission from Ref. [67].

Fig. 7. (Color online) (a) Summary of the shape and size dependence on the chain length of carboxylic acids and amines via hot injection method. Reproduced with permission from Ref. [82]. (b) Overview of CsPbX₃ NCs with different morphologies by varying the organic acid and amine ligands at room temperature. Reproduced with permission from Ref. [83]. (c) Illustration of the effect of increasing the ratio of short chain carboxylic acid to amine ligands on controlling the width of the CsPbBr₃ NWs. Reproduced with permission from Ref. [84]. (d) Illustration of the morphology control of perovskite NCs tuned by the amount of organic amines and organic acids during the synthesis process. Reproduced with permission from Ref. [86].

Fig. 8. (Color online) (a) The sketch showing the change of concentration of different species along with time during CsPbBr₃ synthesis. Inset: schematic illustration of the morphology evolution during CsPbBr₃ synthesis. Reproduced with permission from Ref. [88]. (b) Schematic diagram of the effects of the reaction temperature on tuning the thickness and self-assembly of CsPbX₃ nanoplates. Reproduced with permission from Ref. [90].

Fig. 9. (Color online) (a) The structure illustration of CsPbI_2+xBr_1−x perovskite solar cell using CsPbBrI₂ and CsPbI₃ quantum dots (QDs) as component cells. (b) The halide-ion-profiled heterojunction designed at the CsPbBrI₂/CsPbI₃ QD interface to achieve proper band-edge. (c) The optimization of CsPbI₃ QD layer in the graded bandgap structure to achieve maximum overall light harvesting. (d) The remarkable PCE of the as-fabricated device. Reproduced with permission [153].

Fig. 10. (Color online) (a) Schematic illustration and (b) cross-sectional TEM image of an LED device. (c-e) Photographs and (f) EL spectra (straight line) of LED devices with different halide compositions, and the PL spectra (dashed line) of NCs dispersed in hexane. (g) The Commission Internationale del’Eclairage (CIE) coordinates of the three-color QLEDs (circular) compared to the National Television System Committee (NTSC) color standards (stars). Reproduced with permission from Ref. [155].

Fig. 11. (Color online) (a) Schematic structure of photodetector based on all–inorganic perovskite CsPbI_xBr_3–x. Reproduced with permission from Ref. [140]. (b) Schematic diagram of CO₂ photoreduction over the CsPbBr₃ QD/GO photocatalyst. Reproduced with permission from Ref. [119]. (c) Schematic of a CsPbX₃ (X = Cl, Br, or I) plate on mica substrate pumped by a 400 nm laser excitation. On the right are the emission spectra at five different optical pump fluencies, showing the transition from spontaneous emission to amplified spontaneous emission and to lasing. Inset: 2D pseudo–color plot of the plate emission spectra under different pump fluence (P). Reproduced with permission from Ref. [144]. (d) Schematic illustration of the CsPbBr₃/MoS₂ heterojunction phototransistor. On the right is the comparison of I_sd–V_sd characteristics of this heterojunction in darkness and under a 442 nm laser with different intensities. Reproduced with permission from Ref. [160].