Intense blue emission from one-pot synthesized quaternary CsZnxPb1-xBr3 perovskite quantum dots

Suitable ions incorporation into CsPbX 3 perovskite nanocrystals can improve the luminescence efficiency, chemical stability, and more importantly modify the emission bands from semiconductor band gap change, for various applications. In this research, high content Zn 2+ was introduced into CsPbBr 3 quantum dots through a simple one-pot synthesis method. A new intense blue emission centered at 440 nm was observed from heavy Zn alloyed nanocrystals , for increased semiconductor band gap, along with green emission at 510 nm from CsPbBr 3 quantum dots , when the ratio of ZnBr 2 /PbBr 2 precursor was larger than unity. The appearance of Zn 3d peaks and the decreasing of bonding energy of Pb 4f peaks from X-ray photoelectron spectroscopy spectra indicated that Zn 2+ ions were incorporated into CsPbBr 3 quantum dots to form CsZn x Pb 1-x Br 3 alloyed quantum dots. The elements quantitative analysis showed that partial Zn 2+ ions in precursors were involved in the synthesis of the quantum dots, and the Zn alloyed perovskite nanocrystals could be described as CsPbBr 3 , CsZn 0.43 Pb 0.57 Br 3 , CsZn 0.54 Pb 0.46 Br 3 , CsZn 0.68 Pb 0.32 Br 3 respectively when the ZnBr 2 /PbBr 2 precursor ratios were 0:1, 1:1, 3:1 and 5:1. The X-ray diffraction patterns confirmed that the incorporation of small radius Zn 2+ ions into crystals led to crystal shrinkage, instead of crystal phase change. The transmission electron microscope images of the nanocrystals showed cubic geometries and reduced average sizes from 23.3 nm to 17.6 nm with Zn 2+ content increase, resulting in the blue shift of emission bands. The energy dispersive spectroscopy elemental mapping of nanocrystals also confirmed the incorporation of Zn 2+ ions into the nanocrystals.