The EL performance of the deuterated exciplex-forming hosts was evaluated by fabricating As depicted in Fig. , when subjected to the same driving voltage, the current density of device A is obviously higher than that of device B, allowing it to achieve the saturated photocurrent sooner than device B. Meanwhile, the driving voltage of device A is relatively lower at any luminance level between the turn-on state and their maximum luminance of 44180 highly efficient energy transfer from exciplex-forming hosts to BD-02 emitter (Fig. ). It is worth noting that the spectral shoulder peaks of the device based on deuterated exciplex are lower, which is consistent with the photoluminescence spectra of the doped film shown in Fig. . As a consequence, the CIE coordinates of device A is found to be bluer with smaller CIEy of 0.165, suggesting a positive influence for deep-blue exciplex-forming hosts (Table ). The external quantum efficiency (EQE) and power efficiency (PE) versus luminance curves are shown in Fig. . As illustrated, the maximum PE/EQE values of 41.2 lm W -1 /27.4% were achieved for device A, which were slightly higher than those of contrast device B (36.9 lm W - 1 /27.1%). Notably, the EQE of device A was maintained at a high level of 26.4 and 23.7% at a luminance of 1000 and 5000 cd m -2 , respectively. This corresponds to an efficiency roll-off of only 3.6 and 13.5%, indicating that the device with deuterated exciplex-forming host materials exhibited superior EL stability at high brightness. The device lifetime was then evaluated under initial luminance of 1000 cd m -2 (Fig. ). Impressively long LT90 values of 370 h was observed for device A, which is ~1.6-fold that of the device B based on non-deuterated hosts (~226 h).