The EQE-current density curves, and current density -voltage -radiance curves of our champion devices are shown in Figure and. Our dual ETLs PeLEDs achieve a peak EQE of 0.16% at 2.9 mA/cm 2 with an average EQE of 0.08% over 58 devices (Figure ). At voltages > 5.2 V, the device turned on and reached its maximum radiance of 33 mWsr -1 m -2 at 7.2 V. We did not observe any major change in the EL spectra across a range of operating voltages from 6 to 8 V, with only a small shoulder visible at 6 V. At 6 V, the electric field across the PeLEDs may not be strong enough for electrons to overcome the energetic barriers at the interfaces effectively leading to excitons forming in TPBi.