Deep-Red/NIR Multi-Resonance Delayed Fluorescence Emitters for Efficient OLEDs

Multiple-resonance (MR) thermally activated delayed fluorescence (TADF) materials are the current research hotspot in organic light-emitting diodes (OLEDs) due to their ability to deliver remarkable color purity with full-width-at-half maximum (FWHM < 30 nm) and high efficiency.

However, emission of the majority of reported MR-TADF emitters fell in the blue/green region because of their intrinsic triangulene geometry and limited scope for structural diversity, while examples of emitters addressing the other primary colors required for displays are either rarely (red) or not (Near-Infra Red (NIR)) reported.

In addition, most MR-TADF OLEDs show severe efficiency roll-off and poor operational stability.

Therefore, it is urgent need to make the new molecular designs for producing long-wavelength (> 600 nm) MR-TADF emitters i.e. pure-red/NIR MR-TADF emitters without compromising the emission color purity (FWHM < 25 nm) and efficiency roll-off of OLEDs.

These materials are not only applicable in OLEDs, but also useful in night vision displays, sensors and information-secured displays. To this end, here we proposed two new MR-TADF emitter designs to circumvent the aforementioned drawbacks.

In the first approach, we have designed linearly -extended boron (B)/Nitrogen (N)-based polyaromatic hydrocarbon (PAHs) for shifting the emission into deep-red region. In the second approach, we have proposed a simple, yet versatile design for constructing narrowband NIR emitters. The rationality of the proposed designs were validated by the preliminary computational studies.

This is a highly interdisciplinary project that covers the fields of organic synthesis, computational modelling, physical and optoelectronic characterization, OLED fabrication and testing.

This proposal exploits the two-way transfer of knowledge between the host and the applicant, and the state-of-the-art facilities of the host organization.