A preparation method of Na+/Cu2+ ions co-doped cesium lead bromide perovskite quantum dots, products and applications thereof

The invention relates to a preparation method of Na+/Cu2+ ions co-doped cesium lead bromide perovskite quantum dots, products and applications thereof, which belongs to the technical field of modification research of perovskite quantum dots. The invention discloses a preparation method of Na+/Cu2+ ions co-doped cesium lead bromide (CsPbBr3) perovskite quantum dots, which adopts lead bromide (PbBr2), oleic acid (OA), oleylamine (OAm), sodium ion precursors and copper ion precursors for the reaction preparation in octadecene (ODE), in which copper ions (Cu2+) and sodium ions (Na+) substitute A and B crystal sites in cesium lead bromide (CsPbBr3) perovskite fluorescent quantum dots respectively. The quantum dots have been effectively improved in photoluminescence quantum yield, thermal stability, etc., and can be used as an active layer to fabricate light emitting diodes which achieve the tuning of emission color from green to blue.

TECHNICAL FIELD

The invention belongs to the field of modification research of perovskite quantum dots and relates to a preparation method of Na+/Cu2+ ions co-doped cesium lead bromide perovskite quantum dots, products and applications thereof.

BACKGROUND

Since the first report of the organic-inorganic lead halide perovskite solar cell, halide perovskite is regarded as a well-deserved star material that its cell efficiency has increased to 25.2% in decades. Halide perovskites have attractive application prospects in photovoltaic, photoelectric detection, lighting, displaying, laser and other optoelectronic fields due to their advantages such as emission wavelength tunability, high optical absorption coefficiency and ultra-long carrier diffusion length. In recent years, through the joint efforts of scholars, perovskite materials have made rapid progress in the field of optoelectronics and biological applications. Compared with other materials, the size effect of halide perovskite quantum dots further narrows the luminescence peak and enhances the photoluminescence efficiency. The rich surface of halide perovskite quantum dots has greatly increased the range of performance control, and many novel optical properties and electrical properties have emerged.

Therefore, halide perovskite quantum dots are used in high-definition display, fluorescent biomarker and electrochemistry with great application potential.

Based on the excellent luminescent properties of halide perovskite quantum dots, they are applied to the display field to achieve a wider color gamut, higher color purity and color rendering index than traditional phosphors. Taking all-inorganic perovskite quantum dots as an example, Zeng Haibo's team prepared high-yield multi-color quantum dot materials at room temperature and obtained a white LED with wide color gamut and tunable color temperature. On this basis, in order to reduce the damage of blue light to the human eye, the researchers prepared single-component white light perovskite quantum dots by doping and self-trapping.

In recent years, some metal ions, such as Mn2+, Sn2+, Zn2+ and K+, doped inorganic halide perovskite quantum dots have been shown to enhance their optical properties and stability. However, linking electrons to metal electron ions in electroluminescence remains a difficult task; the radiative transition rates of some ions is much smaller than that of the excitons associated with perovskites. Therefore, metal ion-related photoluminescence will be quenched due to the greatly increased nonradiative transition rate in perovskite quantum dots. This is mainly due to the frequent collisions of injected charge carriers under the action of an electric field, especially for perovskites with high density.

Therefore, in order to realize electroluminescence of metal ions, it is necessary to investigate ions doped halide perovskite quantum dots. In addition, green and red light-emitting diodes based on perovskite quantum dots have been greatly developed, but blue diodes are still facing challenges. This invention explores one method to modify the preparation and composition of cesium lead bromide perovskite quantum dots, which leads to stable blue light-emitting diodes.

INVENTION CONTENT

In view of this, one of the objects of the present invention is to provide a preparation method of Na+/Cu2+ ions co-doped cesium lead bromide perovskite quantum dots; the second object of the present invention is to provide a kind of Na+/Cu2+ ions co-doped cesium lead bromide perovskite quantum dots; the third object of the present invention is to provide an application of Na+/Cu2+ ions co-doped cesium lead bromide perovskite quantum dots in preparing active layer materials for encapsulating blue light-emitting diodes.

To achieve the above purpose, the present invention provides the following technical solution:

Preferably, the molar volume ratio of the lead bromide (PbBr2), oleic acid (OA) and oleylamine (OAm) is (0.4˜1):2:2, mmol:mL:mL;

the molar ratio of the lead bromide (PbBr2), sodium ion (Na+) in the sodium ion precursor and copper ion (Cu2+) in the copper ion precursor is 0.4:(0.01˜0.2):(0.01˜0.2);

Further preferably, the sodium ion precursor is prepared according to the following method: dissolving sodium bromide (NaBr) in N,N-dimethylformamide, stirring to make it completely dissolved.

Further preferably, the molar volume ratio of the sodium bromide (NaBr) and N,N-dimethylformamide is 0.1:2, mmol:ml.

Further preferably, the copper ion precursor is prepared according to the following method: dissolving copper bromide (CuBr2) in N,N-dimethylformamide, stirring to make it completely dissolved.

Further preferably, the molar volume ratio of copper bromide (CuBr2) and N,N-dimethylformamide is 0.1:2, mmol:mL.

Further preferably, the cesium oleate precursor is prepared according to the following method:

Preferably, the mass-volume ratio of the cesium carbonate (Cs2CO3) and oleic acid (OA) added to octadecene (ODE) is 0.8:2.6:(20˜32), g:mL:mL.

Compared with the prior art, the advantages and beneficial effects of the present invention are: the invention discloses a preparation method of Na+/Cu2+ ions co-doped cesium lead bromide (CsPbBr3) perovskite quantum dots, which adopts lead bromide (PbBr2), oleic acid ((A), oleylamine (OAm), sodium ion precursors and copper ion precursors for the reaction preparation in octadecene (ODE), in which copper ions (Cu2+) and sodium ions (Na+) substitute A and B crystal sites in cesium lead bromide (CsPbBr3) perovskite fluorescent quantum dots respectively; the obtained quantum dots have been effectively improved in terms of photoluminescence quantum yield, thermal stability, etc., and can be used as an active layer to encapsulate electroluminescent diodes which achieve the emission color tuning from green to blue through electroluminescence of doped ion-exciton recombination.

Other advantages, objectives and features of the present invention will be illustrated in the following description to some extent, and will be apparent to those skilled in the art based on the following investigation and research to some extent, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description.

DETAILED DESCRIPTION

Embodiments of the present invention are described below through specific embodiments. Those skilled in the art can understand other advantages and effects of the present invention easily through the disclosure of the description. The present invention can also be implemented or applied through additional different specific embodiments. All details in the description can be modified or changed based on different perspectives and applications without departing from the spirit of the present invention. It should be noted that the figures provided in the following embodiments only exemplarily explain the basic conception of the present invention, and if there is no conflict, the following embodiments and the features in the embodiments can be mutually combined.

The present invention will be further described in detail below in conjunction with the accompanying drawings:

A Na+/Cu2+ ions co-doped cesium lead bromide (CsPbBr3) perovskite quantum dot is prepared according to the following method:

A Na+/Cu2+ ions co-doped cesium lead bromide (CsPbBr3) perovskite quantum dot is prepared according to the following method:

A Na+/Cu2+ ions co-doped cesium lead bromide (CsPbBr3) perovskite quantum dot is prepared according to the following method:

A Na+/Cu2+ ions co-doped cesium lead bromide (CsPbBr3) perovskite quantum dot is prepared according to the following method:

A Na+/Cu2+ ions co-doped cesium lead bromide (CsPhBr3) perovskite quantum dot is prepared according to the following method:

A cesium lead bromide (CsPbBr3) perovskite quantum dot is prepared according to the following method:

The CsPbBr3 perovskite quantum dots prepared in Embodiment 1˜6 with different ratios of Cu2+ and Na+ ions co-doped and undoped CsPbBr3 quantum dots are used to form different products;

The CsPbBr3 perovskite quantum dots substituted with different ratios of Cu2+ and Na+ ions replacing A and B sites and the undoped CsPhBr3 quantum dots prepared in Embodiment 1˜6 are added to 5 mL of ethyl acetate. After centrifugation at 6000 rpm for 8 min using a centrifuge, the supernatant is poured out, and the quantum dots at the bottom of the centrifuge tube are re-dispersed into n-hexane. This step is repeated three times, and then a part of the precipitate is dispersed in toluene to prepare a film sample, a part of the precipitate was dispersed in n-hexane to prepare a liquid sample, and a part of the precipitate was dried to prepare a powder sample.

Performance Testing

In summary, the invention discloses a preparation method of Na+/Cu2+ ions co-doped cesium lead bromide (CsPbBr3) perovskite quantum dots, which adopts lead bromide (PhBr2), oleic acid (OA), oleylamine (OAm), sodium ion precursors and copper ion precursors for the reaction preparation in octadecene (ODE), in which copper ions (Cu2+) and sodium ions (Na+) co-doped cesium lead bromide (CsPbBr3) perovskite fluorescent quantum dots; the final product has been effectively improved in terms of photoluminescence quantum yield, thermal stability, etc., and can be used as an active layer to encapsulate electroluminescent diodes which achieve the emission color tuning from green to blue through electroluminescence of doped ion-exciton recombination.

The above descriptions are only examples of the invention, and are not used to limit the protection scope of the invention. For those skilled in the art, the application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this invention shall be included in the protection scope of this invention.