INFORMATION TECHNOLOGY

New progress has been made in the research of near-infrared organic electroluminescence


High-efficiency NIR luminescent materials are attracting attention because of their important applications in bioimaging, medical, optical communications, and night vision devices. However, subject to the energy gap rule, that is, with the decrease of the energy gap difference between the excited state and the ground state, the non-radiative transition rate constant increases exponentially, resulting in the development of high-efficiency organic near-infrared luminescent materials has always been a huge challenge, which seriously limits the improvement of electroluminescence efficiency of related devices. So far, NIR-OLEDs that exhibit pure near-infrared luminescence typically have an electroluminescence efficiency of less than 5%, although a very small number of near-infrared organic light-emitting diodes (NIR-OLEDs) with good performance have achieved an external quantum efficiency of more than 15%.

In response to this problem, Yang Xiaolong, Sun Yuanhui, Zhou Guijiang and others from the School of Chemistry of Xi’an Jiaotong University and Chen Zhao of Wuyi University reported pure near-infrared luminescence NIR-OLED with electroluminescence efficiency of 16.43%. By optimizing the molecular structure design of the Ir(III) complex, the researchers reduced the transition from metal center to ligand charge transfer and improved the ligand-based ππ transition component in the trilinear excited state, successfully reducing the half-peak width of the luminescence spectrum to 43 nm, and obtained a high-efficiency pure near-infrared luminescent material with a maximum emission peak around 730 nm. The researchers prepared the corresponding electroluminescent devices by solution spin-coating method, and obtained pure near-infrared electroluminescence spectra that were nearly consistent with the photoluminescence spectra of the corresponding materials, and the highest electroluminescence efficiency was as high as 15.00% and 16.43%, respectively, which significantly exceeded the reported maximum electroluminescence efficiency of NIR-OLED based on near-infrared Ir(III) complexes. It also significantly exceeds the highest electroluminescence efficiency of NIR-OLED based on different organic near-infrared luminescent materials prepared by solution spin coating.

Narrow-spectrum pure near-infrared luminescent iridium complexes for the preparation of organic light-emitting diodes with external quantum efficiency exceeding 16% by solution method. (Photo courtesy of the research group)

Recently, the research results were published in the international chemical journal “German Applied Chemistry” with the title “Narrow-spectrum pure near-infrared light-emitting iridium complexes for the preparation of organic light-emitting diodes with external quantum efficiency exceeding 16% by solution method”. The first author of the paper is Associate Professor Yang Xiaolong, School of Chemistry, Xi’an Jiaotong University, and the corresponding authors are Associate Professor Sun Yuanhui and Professor Zhou Guijiang of the School of Chemistry, Xi’an Jiaotong University, and Dr. Chen Zhao of Wuyi University. The School of Chemistry of Xi’an Jiaotong University is the first communication unit for papers. (Source: Yan Tao, China Science News)

Related paper information:https://onlinelibrary.wiley.com/doi/10.1002/anie.202309739



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