Zn-Alloyed CsPbI 3 Nanocrystals for Highly Efficient Perovskite Light-Emitting Devices

We alloyed Zn 2+ into CsPbI 3 perovskite nanocrystals by partial substitution of Pb 2+ with Zn 2+, which does not change their crystalline phase. The resulting alloyed CsPb 0.64 Zn 0.36 I 3 nanocrystals exhibited an improved, close-to-unity photoluminescence quantum yield of 98.5% due to the increased radiative decay rate and the decreased non-radiative decay rate. They also showed an enhanced stability, which correlated with improved effective Goldschmidt tolerance factors, by the incorporation of Zn 2+ ions with a smaller radius than the Pb 2+ ions. Simultaneously, the nanocrystals switched from n -type (for CsPbI 3 ) to nearly ambipolar for the alloyed nanoparticles. The hole injection barrier of electroluminescent LEDs was effectively eliminated by using alloyed CsPb 0.64 Zn 0.36 I 3 nanocrystals, and a high peak external quantum efficiency of 15.1% has been achieved.