High-efficiency and long-lifetime deep-blue phosphorescent OLEDs using deuterated exciplex-forming host

A suitable host material is pivotal for efficient and stable deep-blue phosphorescent organic light-emitting diodes (PhOLEDs). Here, we firstly construct a deuterated exciplex-forming host in literature and demonstrate that, besides enhancing molecular stability, deuteration could also reduce molecular reorganization energy and enhance molecular packing density of the host, not only improving its charge transport ability but also reducing shoulder emissions of dopant and accelerating the radiative decay for blue-shifted colour with higher photoluminescence efficiency. The corresponding deep-blue PhOLEDs simultaneously achieve a lower operation voltage and higher maximum external quantum efficiency of 27.4% and power efficiency of 41.2 lm/W. Moreover, a lifetime of 370 h to reach 90% of the initial luminance of 1000 cd/m2 with Commission Internationale de l'Eclairage coordinates of (0.148, 0.165) is achieved, a 1.6-fold enhancement with even blue-shifted colour compared to the protonated counterpart and representing the longest lifetime for deep-blue PhOLEDs at this specific colour.