School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea.
Department of Chemistry and RIGET, Gyeongsang National University, Jinju 52828, Republic of Korea.
Sci Adv. 2023 Jun 2;9(22):eadf1388. doi: 10.1126/sciadv.adf1388. Epub 2023 May 31.
Boron-based compounds exhibiting a multiresonance thermally activated delayed fluorescence are regarded promising as a narrowband blue emitter desired for efficient displays with wide color gamut. However, their planar nature makes them prone to concentration-induced excimer formation that broadens the emission spectrum, making it hard to increase the emitter concentration without raising CIE coordinate. To overcome this bottleneck, we here propose -Tol-ν-DABNA-Me, wherein sterically hindered peripheral phenyl groups are introduced to reduce intermolecular interactions, leading to excimer formation and thus making the pure narrowband emission character far less sensitive to concentration. With this approach, we demonstrate deep-blue OLEDs with of 0.12 and full width at half maximum of 18 nm, with maximum external quantum efficiency (EQE) of ca. 33%. Adopting a hyperfluorescent architecture, the OLED performance is further enhanced to EQE of 35.4%, with mitigated efficiency roll-off, illustrating the immense potential of the proposed method for energy-efficient deep-blue OLEDs.
硼基化合物表现出多共振热激活延迟荧光，被认为是一种很有前途的窄带蓝色发射器，适用于具有宽色域的高效显示器。然而，它们的平面性质使得它们容易发生浓度诱导的激基复合物形成，从而拓宽了发射光谱，使得难以在不提高 CIE 坐标的情况下增加发射体浓度。为了克服这一瓶颈，我们在这里提出了 -Tol-ν-DABNA-Me，其中引入了空间位阻的外围苯基基团以减少分子间相互作用，导致激基复合物形成，从而使纯窄带发射特性对浓度的敏感性大大降低。通过这种方法，我们展示了具有 的深蓝光 OLED，半最大值全宽为 18nm，最大外量子效率（EQE）约为 33%。采用超荧光结构，OLED 性能进一步提高到 EQE 为 35.4%，效率滚降得到缓解，说明了所提出的方法在高效深蓝光 OLED 中的巨大潜力。
