Chinese team develops LED based on copper–iodide clusters
Solution-processed LED approach yields high efficiency, high brightness warm white light
A team led by Yao Hongbin from the University of Science and Technology of China (USTC) has developed a high efficiency, high brightness warm white LED based on copper-iodide cluster hybrids. The work was published in Nature Photonics on December 19th 2023.
Solution-processed LEDs are a promising technology for making the next generation of large-area solid-state lighting. Devices based on lead-halide perovskites, organic semiconductors materials, and colloidal core-shell quantum dots (QDs) have already achieved high electroluminescence performance.
However, some of these solution-processed LED technologies contain toxic heavy metals while others have high production costs due to their complex synthesis.
The USTC researchers decided to tackle this challenge and as a result have created copper-iodide hybrid clusters with both high luminescence efficiency and high solubility. They say the clusters show solubility of more than 200 mg/mL and good structural stability in N, N-dimethylformamide (DMF), the cross-solvent used in LED production.
The luminescent thin films fabricated by spin-coating in DMF exhibit a low surface roughness of 0.22 nm and a high photoluminescence quantum yield of more than 70 percent, which can be used as a luminescent layer to make low-cost warm-white LED devices.
The resulting LED devices achieve a maximum external quantum efficiency of 19.1 percent, a brightness of more than 40,000 cd m-2, and an operational lifetime of more than 232 h (T50@100 cd m-2).
The team made a large-area solution-processed LED device with a working area of 36 cm2 through blade-coating, which exhibited warm white light emission with brightness close to 60,000 cd m-2. By modifying different electron-donating groups on the nitrogen heterocycles of the nitrogen-phosphine chelating ligands, the researchers also developed a series of solution-processed colour-tuneable LED devices.
Reference
Wang, JJ., Feng, LZ., Shi, G. et al. High efficiency warm-white light-emitting diodes based on copper–iodide clusters. Nat. Photon. 18, 200–206 (2024).
