Fig. 5: Characteristics of blue PeLEDs.

a Energy level diagram of the EL devices. b Cross-sectional TEM image of the multi-layered EL device. c EL spectra under forward biases of 3.6, 4.4, and 5.2 V. d Current density–luminance–voltage characteristic of the best-performance device. e EQE–voltage characteristic of the best-performance device. f Histogram of maximum EQEs from 28 devices.