Highly efficient and stable red perovskite quantum dots through encapsulation and sensitization of porous CaF2:Ce,Tb nanoarchitectures
Lead halide perovskite quantum dots (PQDs) are extremely unstable when exposed to oxygen, water and heat, especially red CsPbBrxI3−x (x = 0, 0.5, 1.2) PQDs. This seriously hinders their practical application. Here, red CsPbBrxI3−x (x = 0, 0.5, 1.2) PQDs have been successfully encapsulated in porous CaF2:Ce,Tb hierarchical nanospheres (HNSs), which not only greatly improved the stability of PQDs, benefitting from the protection of the CaF2 shell, but also maintained the high photoluminescence quantum yield (PLQY) of PQDs, benefitting from the sensitization of Tb3+ ions. More importantly, porous CaF2:Ce,Tb nanoarchitectures can prevent aggregation quenching and anion exchange of PQDs. Therefore, the CaF2:Ce,Tb&CsPbBrxI3−x (x = 0, 0.5, 1.2) composite powder can have high PLQY comparable to that of the PQD powder. In view of this, CaF2:Ce,Tb&CsPbBr1.2I1.8 composite based red light-emitting diodes (LEDs) are prepared, and they are very suitable as a supplementary light source for plant lighting. Furthermore, white LEDs are also prepared by coating the CaF2:Ce,Tb&CsPbBr3 and CaF2:Ce,Tb&CsPbBr1.2I1.8 composite on a 450 nm chip. The optimum luminous efficiency is 61.2 lm W−1, and the color rendering index is 91, which are comparable to the current highest values. This shows that the composite composed of PQDs has great potential in LED lighting.
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