Engineering exciton lifetime of Pt(II) complex and templating layer for solution-processed deep-blue phosphor-sensitized fluorescent OLEDs with 36% external quantum efficiency

초록

Achieving solution-processed deep-blue organic light-emitting diodes (OLEDs) with a high color purity and efficiency that betters those of quantum dot and perovskite LEDs remains a challenge in display technology. Here, we report high-performance, solution-processed phosphor-sensitized fluorescent (PSF) OLEDs with a benchmarksetting maximum external quantum efficiency (EQE(max)) of 36.7%, an ultra-narrow full width at half maximum (FWHM) of 19 nm, and CIEx,y coordinates of (0.130, 0.122) with the Blue Index (BI) of 291 cd A(- 1) CIEy- 1, respectively. The newly developed blue-emitting Pt(II) complex, PtON-QBn, featuring an N atom in the alkylaryl (isoquinoline) moiety, effectively enhances spin-orbit coupling (SOC) and reduces the singlet-triplet energy gap, thereby shortening the triplet exciton lifetime to similar to 1 mu s. This molecular design enables efficient energy transfer to the terminal fluorescent emitter, t-Bu-v-DABNA, and significantly improves EQE and suppresses efficiency rolloff. Furthermore, the introduction of a templating layer, polyvinylcarbazole (PVK), promotes horizontal dipole orientation of the emitter, further boosting optoelectronic performance. This integrated material/device strategy represents a significant advance toward the sustainable production of high-performance, non-halogenated deepblue solution-processed OLEDs.

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