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 CsPbX 3 nanocrystals (NCs) as an example to study the structural, morphological and optical properties . We have synthesized monodispersed colloidal inorganic cesium lead halide perovskites (CsPbX 3 , 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 CsPbX 3 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 CsPbBr 3 NCs to Cs 4 PbBr 6 NCs or a mixture of CsPbBr 3 NCs and Cs 4 PbBr 6 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 CsPbI 3 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.