Post-Treatment of CsPbI3 Nanocrystals by p-Iodo-D-Phenylalanine for Efficient Perovskite LEDs

Abstract Inorganic CsPbX3 (X = Cl, Br, I) perovskite nanocrystals (PNCs) have a great promise for LED applications due to their high brightness and tunable emission. However, the long chain capping ligands such as oleylamine and oleic acid function are electrically insulating layers to hinder the charge carrier injection and transport, limiting the device performances. To overcome the limitations, p-iodo-D-phenylalanine (PIDP) was used in the post-treatment process of PNCs to partially substitute the long insulating ligands to improve the conductivity of CsPbI3 PNC films. Besides, the surface defects were also passivated by PIDP, increasing the radiative decay rate and decreasing the non-radiative decay rate, thus enhanced the photoluminescence quantum yield of the PNCs. As a result, highly efficient PNC LEDs were obtained with an external quantum efficiency of 12.4% and a peak luminance of 2000 cd m-2.