Perovskite light-emitting diodes (PeLEDs) based on CsPb(Br/I)3 nanocrystals (NCs) usually suffer from severe spectral instability under operating voltage due to the poor-quality PeNCs. Herein, zeolite was utilized to prepare high-quality CsPb(Br/I)3 NCs via promoting the homogeneous nucleation and growth and suppressing the Ostwald ripening of PeNCs. In addition, the decomposed zeolite interacted strongly with PeNCs through Pb-O bonds and hydrogen bonds, which inhibited the formation of defects and suppressed halide ion migration, leading to an improved photoluminescence quantum yield (PLQY) and enhanced stability of PeNCs. Moreover, the strong binding affinity of decomposed zeolite to PeNCs contributed to the formation of homogeneous perovskite films with high PLQY. As a result, pure-red PeLEDs with Commission International de I'Eclairage (CIE) coordinates of (0.705, 0.291) were fabricated, approaching the Rec. 2020 red primary color. The devices achieved a peak external quantum efficiency of 23.0% and outstanding spectral stability.
Keywords: ion migration; nucleation and growth; perovskite nanocrystals; pure-red light-emitting diodes; zeolites.