Shape-Controlled Synthesis of All-Inorganic CsPbBr₃ Perovskite Nanocrystals with Bright Blue Emission

Abstract

We developed a colloidal synthesis of CsPbBr perovskite nanocrystals (NCs) at a relative low temperature (90 °C) for the bright blue emission which differs from the original green emission (∼510 nm) of CsPbBr nanocubes as reported previously. Shapes of the obtained CsPbBr NCs can be systematically engineered into single and lamellar-structured 0D quantum dots, as well as face-to-face stacking 2D nanoplatelets and flat-lying 2D nanosheets via tuning the amounts of oleic acid (OA) and oleylamine (OM). They exhibit sharp excitonic PL emissions at 453, 472, 449, and 452 nm, respectively. The large blue shift relative to the emission of CsPbBr bulk crystal can be ascribed to the strong quantum confinement effects of these various nanoshapes. PL decay lifetimes are measured, ranging from several to tens of nanoseconds, which infers the higher ratio of exciton radiative recombination to the nonradiative trappers in the obtained CsPbBr NCs. These shape-controlled CsPbBr perovskite NCs with the bright blue emission will be widely used in optoelectronic applications, especially in blue LEDs which still lag behind compared to the better developed red and green LEDs.

Photoelectrochemically Active and Environmentally Stable CsPbBr3/TiO2 Core/Shell Nanocrystals

“…Although the standard pattern of cubic phase CsPbBr 3 mostly overlaps with that of orthorhombic phase, the XRD pattern confirms the CsPbBr 3 NCs exhibit an orthorhombic phase, evidenced by the split diffraction peak at ≈30° ( Figure S6, Supporting Information). [22] For CsPbBr 3 /TiO x composite calcined below 300 °C, the XRD pattern is the same as an orthorhombic CsPbBr 3 phase without TiO 2 peaks due to the amorphous phase of surface TiO x . For CsPbBr 3 /TiO 2 NCs calcinated at 300 °C, two weak diffraction peaks of TiO 2 can be observed (marked with an asterisk in Figure 2c) in addition to the XRD peaks of orthorhombic CsPbBr 3 phase, indicating the formation of TiO 2 shell on the surface of CsPbBr 3 NCs.…”

Fully‐Inorganic Trihalide Perovskite Nanocrystals: A New Research Frontier of Optoelectronic Materials

“…[71] The size and shape of CsPbBr 3 NCs obtained at 170 °C was found to be dependent on the chain length variation of carboxylic acids and amines, ranging from 18 carbons down to two carbons. [99] Similarly, Shamsi and co-workers found that by adjusting the ratio of short (octanoic acid and octylamine) to long (OA and OAm) ligands, the lateral size of CsPbBr 3 nanosheets could be tuned from 300 nm up to 5 µm, while the thickness remained 2−3 unit cells (2.5−3 nm) (Figure 1a-h). [71] The thickness of nanoplatelets also displays a chain-length dependence, as thinner nanoplatelets were produced from shorter chain amines, with the thinnest reaching only three perovskite unit cells.…”

Shape‐ and Trap‐Controlled Nanocrystals for Giant‐Performance Improvement of All‐Inorganic Perovskite Photodetectors

“…Synthesis of CsPbBr 3 NCs : Cs‐oleate precursor solution was prepared following the approach developed by Liang et al with little modification . In brief, 30 mL of ODE was added into a three‐neck flask with 0.8 g of Cs 2 CO 3 and 2.4 mL of OA.…”

“…The HR‐TEM image (Figure f) highlights the CsPbBr 3 nanoribbons with a well‐defined crystalline structure with a cubic lattice parameter of 0.58 nm, along with the crystalline direction of (001) . It looks like these CsPbBr 3 nanoribbons tend to self‐assemble, suggesting that the organic OM mesostructure serves as a template along which the CsPbBr 3 QDs grow aligned, eventually forming a ribbon‐like nanostructure . In order to investigate the microstructure and morphology of the CsPbBr 3 thin films, atomic force microscope (AFM) measurements were performed.…”

“…Likewise, a sharp PL emission peak was detected at 493 nm for the CsPbBr 3 QDs, it shifts to 497 nm for CsPbBr 3 nanocubes and 501 nm for nanoribbons. The peak shift may be attributed to the quantum confinement effect, as the QD is expected to have the largest bandgap broadening, the nanocubes next, and the nanoribbons the smallest . The crystalline structures of the as‐prepared CsPbBr 3 samples were investigated using X‐ray diffraction (XRD).…”