Enhancing the Performance of Perovskite Light-Emitting Diodes by Humidity Treatment.

While humidity treatment has been employed for enhancing the performance of perovskite solar cells and light-emitting diodes (LEDs), only very limited success has been achieved in quasi-two-dimensional (2D) perovskite LEDs (PeLEDs). Here, for the first time, we demonstrate more than one order of magnitude enhancement of the external quantum efficiency (EQE) and electroluminescence (EL) intensity in blue CsPb(Cl/Br) PeLEDs with an organic cation of 2,2-(ethylenedioxy)bis(ethylammonium) (EDBE). Upon humidity treatment, the crystallinity of the three-dimensional (3D) perovskite phase in the EDBE-based perovskite is improved, contributing to an enhancement of photoluminescence quantum yield (PLQY). This work suggests that elaborately modulating the molecular structure of large cations under humidity treatment can serve as an effective strategy to improve the performance of quasi-2D PeLEDs.