New [3+2+1] Iridium Complexes as Effective Phosphorescent Sensitizers for Efficient Narrowband Saturated-Blue Hyper-OLEDs

Two newly designed and synthesized [3+2+1] iridium complexes through introducing bulky trimethylsiliyl (TMS) groups are doped with a terminal emitter of v-DABNA to form an coincident overlapping spectra between the emission of these two phosphors and the absorption of v-DABNA, creating cascade resonant energy transfer for efficient triplet harvesting. To boost the color quality and efficiency, the fabricated hyper-OLEDs have been optimized to achieve a high external quantum efficiency of 31.06%, which has been among the highest efficiency results reported for phosphor sensitized saturated-blue hyper-OLEDs, and pure blue emission peak at 467 nm with the full width at half maxima (FWHM) as narrow as 18 nm and the CIEy values down to 0.097, satisfying the National Institute of Standards and Technology (NIST) requirement for saturated blue OLEDs display. Surprisingly, such hyper-OLEDs have obtained the converted lifetime (LT50) up to 4552 h at the brightness of 100 cd m(-2), demonstrating effective Forster resonance energy transfer (FRET) process. Therefore, employing these new bulky TMS substituent [3+2+1] iridium(III) complexes for effective sensitizers can greatly pave the way for further development of high efficiency and stable blue OLEDs in display and lighting applications.

Automated summary

By introducing bulky trimethylsilyl (TMS) groups, two newly designed and synthesized [3+2+1] iridium complexes, doped with a terminal emitter of v-DABNA, exhibit coincident overlapping spectra between the emission of these two phosphors and the absorption of v-DABNA, enabling efficient triplet harvesting through cascade resonant energy transfer. The optimized hyper-OLEDs achieve a high external quantum efficiency of 31.06%, pure blue emission peak at 467 nm with narrow full width at half maxima (FWHM) of 18 nm, and a CIEy value of 0.097, meeting the requirements for saturated blue OLEDs display set by the National Institute of Standards and Technology (NIST). Furthermore, the hyper-OLEDs demonstrate an impressive converted lifetime (LT50) of up to 4552 h at a brightness of 100 cd m(-2), indicating effective Förster resonance energy transfer (FRET) process. These results highlight the potential of employing bulky TMS substituent [3+2+1] iridium(III) complexes as effective sensitizers for the development of high efficiency and stable blue OLEDs in display and lighting applications.