Researchers build a high-performance NIR OLED device by using redesigned C-shaped OLED materials

Researchers from National Taiwan University, National Yang Ming Chiao Tung University, National Taiwan Ocean University and Academia Sinica used a redesigned C-shaped OLED materials, to create a high-efficiency NIR (1000 nm) OLED device. 

To achieve such a high-efficiency NIR OLED, the researchers replaced a benzene-centered framework with more electron-rich sulfur- and selenium-containing cores. The researchers explain that the stronger electron-rich character promotes intramolecular charge transfer, shifting emission toward 1,000 nanometers, while the rigid C-shaped structure limits molecular relaxation and reduces nonradiative energy loss. The study is published in Advanced Materials.

The researchers tested three types of C-shaped materials (CT-F, CT-Se, and CT-2Se), and found that CT-F showed the most balanced electron and hole transport., and thus was most effective in allowing charges to recombine. But to push into NIR, the researchers used a selenium-containing cores. The researchers build a hyperfluorescent device, where a highly emissive deuterated platinum complex acted as an energy sensitizer, while the C-shaped dye was added as a separate layer by transfer printing. The CT-Se device achieved a 3.07% EQE at 1,000 nm. This is a low EQE for a visible-light OLED, but is actually very high for NIR OLED emission.