Benzothiazole-based Bipolar Hosts for Realizing Highly Efficient OLEDs

Tandem organic light-emitting devices possess desirable qualities such as high luminance, efficiency, and longevity, making them suitable for various applications. The selection of host material for the emitting layer is essential for achieving optimal electroluminescence (EL) performance. To this end, two benzothiazole (BTZ)-based materials, including BTZ-DMAC and BTZ-CZ, were synthesized as bipolar hosts for green phosphors to create high-efficiency OLEDs. Notably, the Ir(ppy)
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-based device employing the BTZ-CZ host demonstrated a peak efficiency of 28.0% (98.8 cd/A and 111.6 lm/W). Furthermore, efficient green tandem OLEDs were produced using the BTZ-CZ host with a specific charge generation layer structure. The maximum efficiency achieved was an ultra-high value of 45.9% (162.9 cd/A and 91.3 lm/W), along with a high maximum luminance. These findings demonstrate that the innovative BTZ-based bipolar hosts have significant potential for developing tandem OLEDs that offer ultra-high performance for various EL applications.