Sn²⁺ ions were introduced in Cs-Pb-Br nanocrystals (NCs) to test the change of crystal structure and photoluminescence (PL) property. In the cases of Sn/Pb ratios less than 20%, the CsPb_1-xSn_xBr₃ NCs revealed CsPbBr₃ crystal structure. With increasing the Sn/Pb ratio, Cs-Pb-Sn-Br NCs exhibited a mixture phase of CsPbBr₃ and Cs₄PbBr₆. The NCs show bright PLQYs (87%) for Sn/Pb molar ratio of 30%. This is ascribed to little amount Cs₄PbBr₆ decreased the electrons and holes non-radiation recombination of CsPbBr₃. With increasing the Sn/Pb ratio to 80%, the Cs₄Pb_1-xSn_xBr₆ NCs exhibited pure Cs₄PbBr₆ phase structure. Furthermore, a weak blue-emitting peak around 450 nm was observed for the Cs₄Pb_1-xSn_xBr₆ NCs. This confirms that Sn²⁺ ions were successfully introduced into Cs₄PbBr₆ structure. The morphologies of samples changed from initial cubic to hexagonal with increasing Sn/Pb ratios from 20 to 80%. The excitons and free carrier dynamics of the NCs were discussed.

Graphical abstract

将Sn ²⁺离子引入Cs-Pb-Br纳米晶体（NCs）中以测试晶体结构的变化和光致发光（PL）性能。在Sn / Pb比小于20％的情况下，CsPb _{1- x} Sn _x Br ₃ NCs显示出CsPbBr ₃晶体结构。随着Sn / Pb比的增加，Cs-Pb-Sn-Br NCs显示出CsPbBr ₃和Cs ₄ PbBr ₆的混合相。NC显示Sn / Pb摩尔比为30％时明亮的PLQY（87％）。这归因于少量的Cs ₄ PbBr ₆降低了CsPbBr ₃的电子和空穴的非辐射复合。随着Sn / Pb比率增加到80％，Cs ₄ Pb _{1- x} Sn _x Br ₆ NCs表现出纯Cs ₄ PbBr ₆相结构。此外，对于Cs ₄ Pb _{1- x} Sn _x Br ₆ NCs，在450 nm附近观察到弱的蓝色发射峰。这证实了Sn ²⁺离子已成功引入Cs ₄ PbBr ₆结构。样品的形态从最初的立方变为六边形，并且Sn / Pb的比例从20％增加到80％。讨论了NC的激子和自由载流子动力学。

图形概要