In situ Surface Reconstruction in Pure Water by Ice-Confined Freeze-Thaw Strategy for High-Performance Core-Shell Structural Perovskite Nanocrystals

Constructing core-shell structure is recognized as an effective approach for the conventional colloidal semiconductor nanocrystals (NCs) to improve their stability and optical performance in optoelectronic applications. It is, however, still a challenge to develop green manufacture for core-shell lead halide perovskite NCs (PeNCs). Herein, an ice-confined freeze-thaw strategy using pure water solvent is devised, which results in the surface reconstruction of CsPbBr3 PeNCs thereby formatting the CsPb2Br5 shell on the CsPbBr3 core to achieve core-shell CsPbBr3@CsPb2Br5. The in situ formation of the CsPb2Br5 shell is attributed to the transformation of the intermediate polyhedral structure with the help of amphiphilic 4-dodecylbenzene sulfonic acid ligand in the precursor solution. The PeNCs show ultrahigh photoluminescence quantum yield of 95%, remarkable stability and humidity-resistance. Moreover, both light-emitting diodes and stretchable fluorescence hydrogels based on the PeNCs exhibit a boosted optical performance and excellent operation stability. The organic solvent-free and recyclability of this strategy pave a novel way to the environmentally friendly and large-scale manufacture of high-quality PeNCs for optoelectronic application.