Synergistic Effects of Surface Ligand Engineering and Double Matrices Protecting Enable Ultrastable and Highly Emissive Blue/Cyan Perovskite Nanocrystal Films for Multifunctional Applications

Perovskite nanocrystals (NCs) have attracted considerable attention because of the extraordinary optoelectronic properties, making them promising candidates for lighting and display applications. However, the emissive efficiency and stability of blue/cyan-emitting NCs lag far behind other color emissive perovskites, which greatly restrict their practical application. Herein, a feasible strategy is proposed for synthesizing highly luminescent and stable CsPbClxBr3-x NCs by the didodecyldimethylammonium bromide (DDAB) ligand-assisted post-treatment. The prepared DDAB-CsPbCl0.8Br2.2 and DDAB-CsPbCl2.0Br1.0 NCs exhibit bright cyan and blue emission, respectively, and their quantum yields are significantly enhanced from 12.2% and 7.5% to 83.1% and 75.3% owing to the obvious decrease of surface defects by the ligand-exchange and halogen-compensation mechanisms. The outstanding fluorescence properties are almost remained by grafting perovskite NCs onto the surface of SiO2 nanospheres. Notably, the ultrahigh water-stability is realized after encapsulating the composite nanospheres into polystyrene-polyisoprene-polystyrene (SIS) film, which is benefit from the triple protection of DDA(+) cations, SiO2 nanospheres and SIS copolymers. The fabricated SiO2@DDAB-CsPbCl2.0Br1.0/SIS film is assembled into an white light emitting diode with high color rendering index of 83.4. Importantly, the blue/cyan-emitting films display superb temperature-sensitivity (30-160 degrees C) and favorable elasticity (1200% stretch rate), indicating their promising application prospect in flexible multifunctional photoelectric devices.

Automated summary

Highly luminescent and stable CsPbClxBr3-x nanocrystals were successfully synthesized by post-treatment with the assistance of the DDAB ligand. The luminescence efficiency of the blue/cyan-emitting nanocrystals was significantly enhanced, and their outstanding fluorescence properties were retained by grafting onto SiO2 nanospheres. The encapsulated composite nanospheres displayed ultrahigh water-stability and were assembled into a white light emitting diode with a high color rendering index. The blue/cyan-emitting films showed excellent temperature-sensitivity and favorable elasticity, indicating their promising application prospect in flexible multifunctional photoelectric devices.