Solution-processed multi-resonance emitters for ultimate displays

Multi-resonance (MR) materials have attracted considerable attention owing to their ability to achieve high color purity emissions with the small full-width at half-maxima (FWHMs) in organic light-emitting diodes (OLEDs), which is crucial for wide color-gamut displays. Nowadays, MR emitters covering almost full color have been developed and applied to construct high-performance narrowband OLEDs. From the commercial perspective of device fabrication, compared with the vacuum-deposition technique, solution processes provide the more economical approaches for the production of low-cost and large-area OLED display panels. Since the device performances of solution-processed MR-OLEDs still lag behind those of vacuum-deposited devices, developing MR emitters featuring intrinsically narrow FWHMs, fast reverse intersystem crossing rate, and good solubility are urgently needed in future cost-effective ultrahigh-definition displays. In this focus review, we summarize the recent advances in solution-processable MR-type emitters, especially for the thermally activated delayed fluorescence molecules. Molecular design, photophysical properties, and solution-processed device performances are correlated. Additionally, the challenges in solution-processed MR-OLEDs and the promising applications of efficient solution-processable MR emitters are also envisaged.