Efficient, narrow-band, and stable electroluminescence from organoboron-nitrogen-carbonyl emitter

Abstract

Organic light-emitting diodes (OLEDs) exploiting simple binary emissive layers (EMLs) blending only emitters and hosts have natural advantages in low-cost commercialization. However, previously reported OLEDs based on binary EMLs hardly simultaneously achieved excellent comprehensive performances, e.g., high efficiency, low efficiency roll-off, narrow emission bands, and high operation stability, which limits their commercialization. To overcome the above long-standing bottleneck, one of the key drivers is to design novel OLED emitter molecules. Here, we thus report a novel molecular-design strategy, i.e., hybridization of organoboron-nitrogen and carbonyl (named h-BNCO). Such a strategy leads to a fast rate of reverse intersystem crossing (RISC) in our newly designed h-BNCO-1 emitter, over 1×106 s-1, which is among the fastest RISC rates in multi‐resonance (MR) emitters and also comparable with those in MR molecules with heavy atoms. The OLED exploiting an EML with h-BNCO-1 achieves not only ultrapure emission with a full width at half maximum of 39 nm but also a maximum external quantum efficiency of over 40% and a mild roll-off of 14% at a practical brightness of 1000 cd·m-2. Importantly, our OLED with such binary EML exhibits good stability (the measured LT95 ~ 137 h for 1000 cd m−2). Here, our work has thus provided not only the h-BNCO molecular-design strategy that goes beyond the previous one for OLEDs with excellent comprehensive performance but also a new chemical template for the design of more novel h-BNCO molecules, thus paving the way to low-cost commercialization of high-efficiency, narrow-band, and high-stability OLEDs.