Fig. 5: LED performance and operational stability.

a Cross-section focused ion beam (FIB) transmission electron microscope (TEM) image. b Energy band diagram based on literature and UPS measurements. c EQE versus current density and d luminance versus voltage characteristics of untreated controls and edge-stabilized perovskite LEDs. e Operational device stability of untreated controls and edge-stabilized perovskite LEDs at a starting luminance of 4000 cd m−2. f Device operational stability of the perovskite LED with MPPO at a starting luminance of 4000 cd m−2.