Highly efficient and stable solution-processed deep-blue OLEDs with LT95 over 50 h at 1000 nit.

[Display omitted] • Adamantyl end-capped groups have potential to boost blue MR-TADF OLEDs' stability. • Adamantyl stabilize excited states by reducing vibronic relaxation in backbones. • Solution-processed deep-blue OLEDs achieved CIE y < 0.08 with a high LT 95 of 55.7 h. Stable solution-processable emitters, particularly deep-blue emitters, are critical for cost-effective and energy-efficient organic light-emitting diodes (OLEDs). In this study, three new multiple resonance (MR) type deep blue emitters with through dual-introduction of methyl and adamantyl as end-capped groups are designed for highly efficient and stable blue fluorescent OLEDs, contributing to doubled device lifetime. Through end-capped modification, the excited states are stabilized via reducing vibronic couplings. Stable deep blue device based on m-DABNA-AdCz are achieved with high current efficiency (CE) of 6.0 cd/A in solution process fluorescent OLEDs and device lifetime up to 95 % of the initial luminance (LT 95) of 55.7 h at 1000 cd m−2, along with the Commission Internationale de l'Eclairage (CIE) coordinates of (0.133, 0.076). This lifetime is the best yet among solution-processed OLEDs of CIE y < 0.08 according to literature to our best knowledge. This work presents a viable strategy for the development of high-performance solution process deep blue fluorescent OLEDs with high color purity and long device lifetime. [ABSTRACT FROM AUTHOR]