Colloidal CsPbX3 (X = Br, I, Cl) NCs: Morphology controlling, composition evolution, and photoluminescence shift

Halide perovskites have attracted enormous attention as a novel optoelectronic material showing bright emission recently. In this paper, we chose CsPbX3 nanocrystals (NCs) as an example to study the structural, morphological and optical properties. We have synthesized monodispersed colloidal inorganic cesium lead halide perovskites (CsPbX3, X = Cl, Br and I, or mixed lead halide CsPb(Cl/Br)(3) and CsPb(Br/I)(3)) NCs with various morphologies and brightly luminescent properties. The emission wavelength of resulting CsPbX3 NCs can be tuned from 440 nm to 696 nm by varying the amount of different Pbx(2) (X = Cl, Br and I), while maintaining high quantum yields up to 95% and narrow emission spectra. The average lifetime of the NCs is several ns to hundred with changing the composition. The blinking of the NCs in terms of a binary (on/off) process is different from II-VI quantum dots. Interestingly, we find that CsPbBr3 NCs to Cs4PbBr6 NCs or a mixture of CsPbBr3 NCs and Cs4PbBr6 NCs were obtained by adjusting the amount of oleic acid (OA)-Cs precursor. The optical properties of these NCs have been controlled by varying their composition. Moreover, the injection speed of Cs-OA precursor enables the control of CsPbI3 NCs with different morphology, which can be tuned from litter nanoparticles to uniform nanorods. This finding can serve as an ideal platform for the investigation of fundamental properties.