Decoupling the Exciton‐Carrier Interaction for Highly Efficient Pure Blue Perovskite Light‐Emitting Diodes Exceeding 20%

Abstract Pure blue emission (wavelength ≤ 470 nm) is essential for perovskite light‐emitting diodes (PeLEDs) in the application of future displays. However, the performance of the pure blue PeLEDs is far away from the application requirement and theoretical values. The charging of excitons plays a crucial role in the non‐radiative decay of the high‐energy blue perovskite emitters under electric fields. Here, a designed exciton‐carrier decoupling emitting layer (De‐EML) is reported which can simultaneously suppress the formation of charged excitons and facilitate the injection of carriers. By tuning the energy levels of each QD layer in the De‐EML, the photoluminescence quantum yield (PLQY) reached 83.7%, and the Auger recombination related to exciton‐carrier coupling in high excitation intensities is suppressed. Based on the designed De‐EML, high‐performance pure‐blue PeLEDs (emission at 469 nm) with an EQE of 20.3% and an operational lifetime (T 80 ) of 4.8 h at 1070 cd m −2 is demonstrated. A record maximum brightness of 31 407 cd m −2 is also achieved.