Enhancing the operational stability of OLED devices through the utilization of deuterated TTU host materials

Recent research on anthracene-based hydrocarbon (PNA) as the emissive layer host found that deuteration mediated the formation of these adduct species, presumably quenchers, and thus improved the device lifetime. Meanwhile, studies on deuterium in PNA host materials with stepwise deuteration are scarce. In this work, we report a systematic study of isotopic effects through independent deuteration of the phenyl or/and the dibenzofuran unit on a series of PNA materials polyaromatic dibenzofuran (PAF, PAF-d5, PAF-d7 and PAF-d12). We fabricated fluorescent OLED based on this triplet-triplet up-conversion active host materials for conventional MR-TADF emitter. A short-lived excited delayed lifetime of less than 2 μs has been observed in their electroluminescence decay studies. In addition, LT80 of up to 12.7 h has been observed in PAF-d12 at the brightness of 1000 cd m−2, corresponding to a 4-fold enhancement of OLED stability compared to the non-deuterated counterpart. We hope the current research can provide insights for further device improvement.