In Situ Formed Perovskite Nanocrystal Films Toward Efficient Circularly Polarized Electroluminescence

Circularly polarized electroluminescence (CPEL) is an active area of research because of its wide application in 3D displays and anti‐counterfeiting. However, it is not trivial to obtain a high asymmetry factor for highly efficient CPELs. Herein, a highly efficient CPEL is demonstrated with a superior asymmetry factor by using a chiral phosphine‐oxide‐passivated perovskite film as an emitter. An in situ‐formed perovskite nanocrystalline (NC) film is obtained by passivation of the chiral phosphine oxide. The as‐formed film exhibits much‐enhanced photoluminescence compared with the pristine film. More importantly, the NC film exhibits excellent chiral photoluminescence with a luminescence dissymmetry factor glum as high as 5.6 × 10−3. Electrically driven light‐emitting diodes based on the NC film exhibited superior device performance with a maximum brightness of 18,783 cd m−2 and a peak external quantum efficiency of 3.6%. More encouragingly, an unprecedented electroluminescence asymmetry factor gEL of up to 0.18 is achieved because of the chiral lattice distortion of the perovskite, which is the state‐of‐the‐art among hybrid materials. A highly efficient CPEL solution is presented with superior asymmetry, achieved by utilizing a chiral phosphine‐oxide‐passivated perovskite film. This research introduces an in situ‐formed perovskite nanocrystalline (NC) film, displaying significantly enhanced photoluminescence and excellent chiral photoluminescence. Notably, electrically driven light‐emitting diodes based on this film outperform, reaching an unprecedented electroluminescence asymmetry factor, setting a new standard in hybrid materials.