A team led by Prof. CUI Songlin at University of Science and Technology of China (USTC) of the Chinese Academy of Sciences, collaborating with Prof. ZHOU Meng's team from Beijing Information Science and Technology University, proposed a new strategy for designing pure-red organic light-emitting diode (OLED) materials which achieve high electroluminescence efficiencies, marking one step towards high-performance ultrahigh-definition OLED displays. The study was published online in Journal of the American Chemical Society.

OLEDs have emerged as a leading technology due to their unique features such as flexibility and bright self-emission. It has been found that the performance of red OLEDs, especially in the saturated red region, has lagged behind that of blue and green counterparts. The development of efficient red emitters with high color purity is a challenge.

In this study, researcher proposed a new strategy for designing pure-red OLED materials with high luminous efficiency, excellent color purity, and long-term stability. The key innovation lies in the molecule BNTPA, which is designed to incorporate secondary electron-donating units and extend the π-skeleton within multiresonance cores. This structural modification significantly enhances intramolecular charge transfer, enabling the molecule to more efficiently handle the excitation energy. As a result, light emission was effectively shifted into the red spectrum, while still maintaining narrowband characteristics for ensuring high color fidelity, which is a key requirement for high-definition displays. 

To further improve the molecular design, researchers optimized the reverse inter-system crossing (RISC) process. The refined structure of BNTPA not only accelerates the RISC rate but also ensures a balanced combination of short-range and long-range charge transfer characteristics. 

This balance is particularly important for improving the overall photophysical performance of the emitter, as it minimizes energy loss and improves both the luminous efficiency and stability of the OLEDs. In addition, the integration of secondary electron-donating units stabilizes the excited states of BNTPA, reducing non-radiative decay and preventing energy loss that often occurs in red-emitting materials. This enhancement of the molecular architecture ensures that BNTPA-based OLEDs achieve greater operational stability and longer lifetimes, making them suitable for practical, long-term use in real-world applications.

OLEDs based on BNTPA achieved a record-breaking external quantum efficiency exceeding 43%. Its CIE value (0.657, 0.343) aligns closely with NTSC standards (0.67，0.33), achieving excellent color purity. These are attributed to the optimized design of the molecule, which enhances energy efficiency and operational stability. BNTPA is established as a benchmark for next-generation high-performance red multiresonance-induced thermally activated delayed fluorescence emitters.

This study contributes to the development of energy-efficient and durable lighting systems, enabling OLED displays to meet stringent color standards.