Lim Hyoungcheol, Cheon Hyung Jin, Woo Seung-Je, Kwon Soon-Ki, Kim Yun-Hi, Kim Jang-Joo
Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, South Korea.
Department of Chemistry and RIGET, Gyeongsang National University, Jinju, 52828, South Korea.
Adv Mater. 2020 Nov;32(47):e2004083. doi: 10.1002/adma.202004083. Epub 2020 Oct 20.
New blue (DBA-SAB) and deep-blue (TDBA-SAF) thermally activated delayed fluorescence (TADF) emitters are synthesized for blue-emitting organic-light emitting diodes (OLEDs) by incorporating spiro-biacridine and spiro-acridine fluorene donor units with an oxygen-bridged boron acceptor unit, respectively. The molecules show blue and deep-blue emission because of the deep highest occupied molecular energy levels of the donor units. Besides, both emitters exhibit narrow emission spectra with the full-width at half maximum (FWHM) of less than 65 nm due to the rigid donor and acceptor units. In addition, the long molecular structure along the transition dipole moment direction results in a high horizontal emitting dipole ratio over 80%. By combining the effects, the OLED utilizing DBA-SAB as the emitter exhibits a maximum external quantum efficiency (EQE) of 25.7% and 1931 Commission Internationale de l'éclairage (CIE) coordinates of (0.144, 0.212). Even a higher efficiency deep blue TADF OLED with a maximum EQE of 28.2% and CIE coordinates of (0.142, 0.090) is realized using TDBA-SAF as the emitter.
通过分别将螺二吖啶和螺吖啶芴供体单元与氧桥联硼受体单元相结合，合成了用于蓝色有机发光二极管（OLED）的新型蓝色（DBA-SAB）和深蓝色（TDBA-SAF）热激活延迟荧光（TADF）发光体。由于供体单元具有较深的最高占据分子能级，这些分子呈现出蓝色和深蓝色发射。此外，由于刚性的供体和受体单元，两种发光体均表现出半高宽（FWHM）小于65nm的窄发射光谱。此外，沿跃迁偶极矩方向的长分子结构导致水平发射偶极比高达80%以上。综合这些效应，以DBA-SAB作为发光体的OLED表现出25.7%的最大外量子效率（EQE）和1931国际照明委员会（CIE）坐标（0.144, 0.212）。使用TDBA-SAF作为发光体，甚至实现了更高效率的深蓝色TADF OLED，其最大EQE为28.2%，CIE坐标为（0.142, 0.090）。
