Abstract: Although organic light emitting devices (OLEDs) based on thermally activated delayed fluorescence (TADF) have already realized impressively high external quantum efficiency (EQE) of over 35%, their operation lifetime should still be improved for practical applications. In this study, we developed a molecular design for high triplet energy (ET = 2.7 eV) multifunctional hole-transport layers (HTLs) based on a hexaphenylbenzene skeleton to realize record-breaking efficient and stable TADF OLEDs. By using a dibenzofuran-end-capped HTL named 4DBFHPB, we could successfully develop a highly efficient, low-drive voltage, and stable green TADF OLED exhibiting EQE of 19.2% and operation lifetime at 50% (LT50) of ~24,000 h at an initial luminance of 1000 cd m−2. The drive voltage at 1000 cd m−2 was recorded to be 4.07 V. We also developed a sky-blue TADF OLED exhibiting hext of 21.5% and LT50 of ~1700 h at an initial luminance of 500 cd m−2. The developed designs demonstrate record-breaking performances among the existing TADF OLEDs.

📚　Kido/Sasabe/Chiba Lab HP >>　https://oled.yz.yamagata-u.ac.jp/view.cgi?p=373