Perovskite nanocrystals-polymer composites with a micro/nano structured superhydrophobic surface for stable and efficient white light-emitting diodes

Metal halide perovskite nanocrystals (PNCs) offer excellent optoelectronic properties for light-emitting diodes (LEDs). However, the low chemical stability against water hinders their practical application. Herein, we develop a phase separation strategy to realize highly luminescent PNC-polymer composites with a superhydrophobic micro/nano structured surface. Ethyl α-cyanoacrylate (ECA) monomers and octavinyloctasilasesquioxane (OVS) are added into the PNC toluene solution together. Due to high reactivity of ECA toward H 2 O, the poly (ethyl α-cyanoacrylate) (PECA) polymer matrix (first phase) is initially formed via a rapid anion polymerization reaction in a humid environment. As the evaporation of toluene, the OVS is then condensed into the micro/nano-scale protrusions (second phase) on the PECA substrate because of the strong Si-O bonds between OVS molecules, and the PNCs are uniformly encapsulated within the two polymers. We find that besides the increased quantum efficiency, the chemical stability of the resulting PNC-PECA-OVS composites is remarkably enhanced. Immersing the superhydrophobic composites into water, the PL intensity still maintains ∼ 60% even after 1000 h. In contrast, the PL emission of pristine PNCs is completely quenched after only 10 min. By curing the green PNC-polymer composites with commercially available red-emitting phosphors on a blue-emitting InGaN chip, we demonstrate a long-term stable and efficient white LED with a high power efficiency of ∼ 93 lm/W and almost constant color-correlated temperature (CCT).