In Situ Phase-Transition Crystallization of All-Inorganic Water-Resistant Exciton-Radiative Heteroepitaxial CsPbBr₃–CsPb₂Br₅ Core–Shell Perovskite Nanocrystals

Abstract

The instability of metal halide perovskites upon exposure to moisture or heat strongly hampers their applications in optoelectronic devices. Here, we report the large-yield synthesis of highly water-resistant total-inorganic green luminescent CsPbBr 3 /CsPb 2 Br 5 core/shell heteronanocrystals (HNCs) by developing an in situ phase transition approach. It is implemented via water-driven phase transition of the original monoclinic CsPbBr 3 nanocrystal and the resultant tetragonal CsPb 2 Br 5 nanoshell has small lattice mismatch with the CsPbBr 3 core, which ensures formation of an epitaxial interface for the yielded CsPbBr 3 /CsPb 2 Br 5 HNCs.These HNCs maintain nearly 100% of the original luminescence intensity after immersion in water for eleven months and the luminescence intensity drops only to 81.3% at 100 °C. The transient luminescence spectroscopy and density functional theory calculation reveal that there 1 are double radiative recombination channels in the core CsPbBr 3 nanocrystal, and the electron potential barrier provided by the CsPb 2 Br 5 nanoshell significantly improves the exciton recombination rate. A prototype quasi-white light-emitting device based on these robust CsPbBr 3 /CsPb 2 Br 5 HNCs is realized, showing their strong competence in solid-state lighting and wide color-gamut displays.

Optimizing optical properties of hybrid core/shell perovskite nanocrystals

“…9 Therefore, it is essential to improve the optical stability of hybrid perovskite NCs to break the barrier toward their practical application. [10][11][12] Over the past several years, various methods have been developed to improve the optical properties of semiconductor NCs, including surface chemistry, 13,14 core-shell nanostructures, 15,16 doping, 17 and alloying. 18,19 Among the abovementioned methods, the design of core-shell nanostructures has been proven to be an efficient method that can improve the optical properties of semiconductor NCs.…”

“…18,19 Among the abovementioned methods, the design of core-shell nanostructures has been proven to be an efficient method that can improve the optical properties of semiconductor NCs. 16,20,21 In this case, the NCs' surfaces are passivated by a semiconductor shell with a larger band gap. For example, the optical properties of InP and CdSe NCs can be optimized by the growth of a semiconductor shell, including ZnS, ZnSe and CdS.…”

Stable CsPbX3/ZnO Heterostructure Nanocrystals for Light-Emitting Application

“…Construction of heterostructure nanocrystals offers an effective approach to passivate the surface of PNCs that fundamentally improves their environmental stability . Recent research has centered on exploring PNC-based heterostructure nanocrystals, and the selection of the semiconducting materials includes halides, − metal chalcogenide, − and oxides. , Thereinto, growth of wide bandgap oxides, such as SiO 2 , , and ZrO 2 is particularly attractive because of their excellent air/moisture resistance. However, current methods for growing oxides on PNCs utilize the hydrolysis reaction of metal alkoxides, which forms amorphous oxides with an unsatisfying oxygen/moisture barrier …”

Effects of Tellurium Doping on Environmental Stability and Luminous Performance of CsPbBr3 Quantum Dots

“…For the x=1.6 sample, the increasing degree coating CsPbBr 3 by CsPb 2 Br 5 increases the overlap of wavefunctions of the electrons and holes and thus decreases the FWHM for enhanced radiative quantum transition rate. 23 Unfortunately, because CsPb 2 Br 5 has an indirect band gap, the intensity of PL emission decreases by several magnitudes and thus can not be observed by bare eyes under UV light illumination.…”