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Synthesis of Perovskite Quantum Dots

Compared with traditional cd-based quantum dots, perovskite quantum dots show better optical properties, such as tunable emission wavelength, narrower half-peak width, high quantum yield, and full solution treatment. Therefore, it has been widely concerned by people and has a broad application prospect in the field of lighting and display.

Synthesis of Perovskite Quantum Dots

The synthetic methods [1]


Hot-injection

Photographs under UV lamp(a) and PL spectra(b)of perovskite synthesized by hot-injection method

Since Protesescu [2] first reported the synthesis of all-inorganic perovskite quantum dots by hot- injection, it has been widely used in the synthesis of traditional semiconductor NCs and hybrid organic-inorganic perovskites quantum dots. Cesium oleate precursor prepared in advance was rapidly injected into octadecene high-temperature solution containing lead halide salt (PbX2) and ligand. After a certain reaction time, CsPbX3 (X = Cl, Br, I) QDs were obtained by rapid cooling in ice water bath. By changing the type and ratio of halogen and adjusting the reaction time and temperature, quantum dots of different sizes and luminous colors can be obtained.


Microwave synthesis

Schematic illustration of the synthetic process of colloidal CsPbX<sub>3</sub> perovskite quantum dots by microwave irradiation.

Microwave synthesis can achieve uniform heating, thus controlling the crystallization rate and achieving mass production that cannot be achieved by hot-injection. Microwave radiation can increase the solubility of the solid precursor and accelerate its dissolution at the liquid-solid interface, at which time the seed formation. Subsequently, in the presence of the end ligand and continuously dissolved precursor, the seed is exposed to promote crystal growth, and the growth rate can be controlled by the dissolution rate of the precursor. Finally, microwave radiation is stopped and the reaction is terminated by thermal quenching, that is, CsPbX3 quantum dots are obtained. Long's group [3] firstly synthesized perovskite quantum dots using this method.


Anion exchange method

Different routes and precursors for the an- ion exchange reactions on CsPbX3 quantum dots

Anion exchange method is an effective method to obtain different bandgap widths and change absorption spectra. The optical properties of colloid are regulated by changing the halide ratio. After mixing the synthesized perovskite quantum dots with different kinds of lead halide salts, CsPbX3 quantum dots at any wavelength in the visible spectrum can be obtained through rapid halide ion exchange, and the crystal shape and morphology remain unchanged. Meanwhile, fluorescence spectra showed that the anion exchange process did not destroy the structure and overall stability of the initial quantum dots [4].


Perovskite quantum dots have attracted the attention of scientists all over the world. The optical properties of perovskite quantum dots are closely related to the preparation method. In addition to the above general synthesis method, the synthesis method of perovskite quantum dots also includes supersaturated recrystallization method, ultrasonication method, microfluidic reactor method, solvothermal reaction and so on [5].

References

  • Wang-yu Liu.; et al, Synthesis, Properties and Application of All-inorganic Perovskite Quantum Dots[J]. Chinese Journal of luminescence, 2020, 41(2): 117-133.
  • Protesescu.; et al, Nanocrystals of cesium lead halide perovskites (CsPbX3, X = Cl, Br, and I) : novel optoelectronic materials showing bright emission with wide color gamut [J]. Nano Lett. , 2015,15(6) : 3692-3696.
  • Long Z.; et al. High-throughput and tunable synthesis of colloidal CsPbX3 perovskite nanocrystals in a heterogeneous system by microwave irradiation[J]. Chem. Commun., 2017, 53(71): 9914-9917.
  • Akkerman Q A.; et al. Tuning the optical properties of cesium lead halide perovskite nanocrystals by anion exchange reactions[J]. J. Am. Chem. Soc., 2015, 137(32): 10276-10281.
  • Chen D, Chen X. Luminescent perovskite quantum dots: synthesis, microstructures, optical properties and applications[J]. Journal of Materials Chemistry C, 2019, 7(6): 1413-1446.

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