Researchers from Korea's PEROLED, Seoul National University and Korea Basic Science Institute (KBSI), along with scientists from the UK's University of Cambridge, have reported an ultra-bright, efficient and stable perovskite LED made of core/shell perovskite nanocrystals with a size of approximately 10 nm, obtained using a simple in situ reaction of benzylphosphonic acid (BPA) additive with three-dimensional (3D) polycrystalline perovskite films, without separate synthesis processes.
During the reaction, large 3D crystals are split into nanocrystals and the BPA surrounds the nanocrystals, achieving strong carrier confinement. The BPA shell passivates the undercoordinated lead atoms by forming covalent bonds, and thereby greatly reduces the trap density while maintaining good charge-transport properties for the 3D perovskites.
The team demonstrated efficient, bright and stable perovskite LEDs with a maximum brightness of approximately 470,000 cd m−2, maximum external quantum efficiency of 28.9% (average = 25.2 ± 1.6% over 40 devices), maximum current efficiency of 151 cd A−1 and half-lifetime of 520 h at 1,000 cd m−2 (estimated half-lifetime >30,000 h at 100 cd m−2). Their work sheds light on the potential of perovskite-based LEDs to be commercialized in the future display industry.