Bo Wang,Shan Zhang,Bin Liu,Jinkai Li,Bingqiang Cao,Zongming Liu
CsPbBr3 perovskite quantum dots (QDs) have attracted great attention due to their different photoluminescent and electronic properties. However, the toxicity and low stability hinder their practical application. Here, low-toxicity Sn-substituted cesium lead bromide perovskite QDs were synthesized via the room temperature crystallization method. A phase transition of the perovskite quantum dots with the concentration of Sn increasing was found: the crystal phase of CsPbBr3:Sn perovskite QDs starts to be transformed into Cs4PbBr6:Sn perovskite QDs when the SnBr2 precursor exceeds 30 at. %. In this process, the controlled-color emission of perovskite QDs from green to blue can be realized. To improve the stability of quantum dots, CsPbBr3:Sn@SiO2 and Cs4PbBr6:Sn@SiO2 were synthesized via a simple one-step synthesis with hydrolysis of tetramethoxysilane in toluene solution containing perovskite QDs. The results show that CsPbBr3:Sn@SiO2 and Cs4PbBr6:Sn@SiO2 exhibited higher water stability and water solubility than pure QDs. In a mixed solution of toluene and water, the PL intensity of the CsPbBr3:Sn@SiO2 retained 46.7% and the Cs4PbBr6:Sn@SiO2 was 59.6% even after 24 h of reaction compared with the initial intensities. These quantum dots with good stability and luminescent property developed in this work are expected to be widely used in light-emitting diodes.
All-inorganic perovskite materials have attracted much attention in the field of photocatalysts due to their unique photoelectric properties.However, the inherent poor stability of perovskite quantum dots significantlyhinders their practical applications. Herein, to settle the instabilities of inorganic perovskite materials, Sn-TiO 2 coated CsPbBr 3 quantum dots named CsPbBr 3 /Sn-TiO 2 , are fabricated via resaturated recrystallization, sol–gel coating and solvothermal crystallization.The XRD results demonstrated that the core–shell structure of CsPbBr 3 /Sn-TiO 2 nanocrystals was successfully synthesized.Moreover, excellent dispersion is verified for CsPbBr 3 /Sn-TiO 2 nanocrystals with a core–shell structure by TEM. The particle size of CsPbBr 3 /Sn-TiO 2 nanocrystals is 15–30 nm, where the core size for CsPbBr 3 quantum dots is 4–8 nm, and the Sn-TiO 2 shell thickness is 2–8 nm.The photocatalytic activity of nanocomposites was studied by the photodegradation of RhB aqueous solution under the irradiation of 100 mWcm −2 air mass 1.5 global AM1.5G sunlight. Compared with traditional photocatalyst P25, the core–shell structured CsPbBr 3 /Sn-TiO 2 nanocrystals exhibited better photocatalytic performance, with a degradation efficiency of 96.6% and a degradation rate constant of 10.68 × 10 -2 min −1 in 30 min of catalytic time, which was five times higher than that of P25.The core–shell structured CsPbBr 3 /Sn-TiO 2 nanocrystals have long-term stability in water system and have potential practical application value in the field of environmental governance.
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