"Impossible Trinity" between Efficiency, Stability, and Color Purity for Blue OLEDs: Challenges and Opportunities.

Organic light-emitting diodes (OLEDs) have become the cutting-edge technology in the display market. However, compared with green and red stacks, blue stacks still remain an obstacle for OLED technology. There seems to be an "impossible trinity" between efficiency, stability, and color-purity for blue OLEDs. In this trilemma, advances in device stability have lagged far behind. In this Perspective, focusing on the critical role of bond-dissociation energy (BDE), we first summarize recent advances in the chemical degradation mechanism of high-efficiency blue OLED materials and then highlight strategies to improve the intrinsic stability and device lifetime from the material point-of-view. Finally, future challenges and opportunities for developing robust blue OLED materials and devices are envisioned, including the rational design of robust blue materials with high BDEs, two-pronged approaches from both thermodynamic and kinetic aspects, the great need for robust host materials, deep insights into host-guest interactions, collaborative efforts from the aspect of devices, and data-driven screening and iteration development.