Fig. 3: Characterization of Ge–Pb PeLED performance.

a Schematic of the Ge–Pb PeLED device structure. b Flat-band energy level diagram of a Ge–Pb PeLED. c A STEM-HAADF image of the cross-section of a Ge–Pb PeLED. d EDS elemental maps of Cs, Pb, and Ge in the same area enclosed by the dashed box in (c). e The EL spectra across a range of operating voltages. Inset: a photograph of a working Ge–Pb PeLED. f EQE-current density curves for PeLEDs with 0 mol%, 10 mol%, and 20 mol% Ge inclusion. g Current density-luminance-voltage characteristics of the best-performing PeLED with 10 mol% Ge inclusion.