Fig. 1

Device structure and efficiency roll-off of perovskite MQW LEDs. a Schematic representation of the flat-band energy level diagram and structures of the 30-nm thick perovskite MQW film which is an assembly of different layered lead halide perovskites with various n numbers. The n number determines the bandgap of each quantum well. The MQW structure enhances the probability of radiative recombination. b Dependence of current density (blue triangles), normalized PLQE (black square), and EQE (red circle) on the driving voltage. The PLQE and EQE were measured simultaneously on a working LED device. The excellent correlation between the PLQE and EQE at high current intensities indicates that luminescence quenching is responsible for the EQE roll-off