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 x 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.image"]