On August 19, Professor Yang Chuluo's team from the College of Materials Science and Engineering at Shenzhen University (SZU)published a research paper titledDeep-blue organic light-emitting diodes for ultrahigh-definition displaysin the prestigious international journalNature Photonics(https://doi.org/10.1038/s41566-024-01508-w). This is the second research paper published by Professor Yang's team inNature Photonics, with SZU as the sole institutional affiliation.Nature Photonics, ranked first in the OPTICS - SCIE category with a recent impact factor of 32.3, is classified as a Tier-1 journal by the Chinese Academy of Sciences' journal ranking system.
Organic light-emitting diodes (OLEDs) have become widely adopted in small- to medium-sized displays as a next-generation flat-panel display technology. As display technology advances toward ultra-high definition, OLEDs are now facing increasingly stringent requirements. OLED materials and devices with narrow-spectral-band emission are essential for achieving high color purity and saturation, which are crucial for high-definition displays. As is well known, blue light-emitting materials have long been both crucial and challenging in OLED technology. Developing narrow-spectrum blue organic materials with high color purity remains particularly difficult and presents significant challenges.
Recently, Professor Yang Chuluo and his research team at SZU have introduced a novel molecular design strategy for multiple-resonance thermally activated delayed fluorescence (MR-TADF) materials, characterized by a boron-nitrogen heteroaromatic fused-ring structure. This strategy, focusing on "resonance framework expansion with synergistic twisting configuration," has fostered the development of a new narrow-spectrum blue light-emitting molecule. The optimized emitter exhibits high rigidity, strong spin-orbit coupling, and minimized bonding/antibonding orbital character, resulting in an exceptionally narrow emission spectrum and rapid spin flip. Experimental results show that the optimal molecule emits deep-blue light at a peak of 458 nm with a full width at half maximum (FWHM) of just 12 nm in toluene solution. It also has a reverse intersystem crossing rate constant (kRISC) of 2.29 × 106 s−1. The related single-unit organic light-emitting diode achieves an external quantum efficiency of 39.2% with color coordinates of (0.141, 0.050) and a narrow full-width at half-maximum of 14 nm. Further refinement of the device structure has achieved an exceptional external quantum efficiency (EQE) of 74.5% in a sensitized stacked device, along with a low efficiency roll-off. This breakthrough in OLED color purity and luminous efficiency in the deep-blue spectrum marks a significant advancement in the development of wide-color-gamut ultra-high-definition OLED display technology.
Associate Research Fellow Hua Tao, Associate Professor Cao Xiaosong, and Assistant Professor Miao Jingsheng from the College of Materials Science and Engineering at SZU are co-first authors of this research. Professor Yang Chuluo is the corresponding author, and SZU is the sole institutional affiliation. The research was funded by the Key Program of the National Natural Science Foundation of China, the Guangdong Provincial Basic and Applied Basic Research Project, the Shenzhen Science and Technology Innovation Bureau, and Shenzhen University.
