1. Could you explain the significance of your article to the non-specialist? 

White organic and polymeric light-emitting diodes (WOLEDs and WPLEDs) have attracted considerable attention because of their potential applications in solid-state lighting and as back-panel lighting for liquid crystal displays. We have developed stable and highly efficient electrophosphorescent WPLEDs by utilizing a blue-emitting polymeric host containing charge-transporting side chains. In addition, the simplified device architecture and manufacturing process of these PLEDs make them attractive for the future development of solid-state lighting.

2. What has motivated you to conduct this work? 

The blue-emitting fluorene copolymer PF-TPA-OXD has proved to be very useful as the host material for various polymers-based, fluorescent or phosphorescent PLEDs. This host polymer, which contains both hole-transporting triphenylamine (TPA) units and electron-transporting oxadiazole (OXD) side chains, is capable of facilitating charge injection and transport, and is suitable for matching the dopant-host energy level to achieve the direct formation and confinement of an exciton at the dopant. Hence, aimed at fabricating efficient and stable white PLEDs, we have made great efforts to use this blue-emitting host material, physically blended with a related green-emitting copolymer and a red-emitter such as the high efficiency osmium-based phosphor

3. Where do you see this work developing in the future? 

One of the main reasons for the low luminous efficiency and the high operating voltage is the charge imbalance in the emissive layers. The charge injection and transport properties of the materials are crucial for maximizing the exciton recombination in the emissive layer and improving the device efficiency. We expect that the performance of our tailor-made polymer blend can be further enhanced by fine-tuning their structures and functional constituents, as well as by optimizing the device structure.

4. Are there any particular challenges facing future research in this area? 

A great challenge for the white PLEDs is to develop certain commercial products that can compete with existing illumination sources.  The characteristics such as low-cost manufacturability, high device efficiency, good color quality, and decent operation lifetime are essential for the design and fabrication of WPLEDs. The relevant factors, which require thorough understanding and optimization, provide immense research opportunities in this field.