Employing Heavy Metal-Free Colloidal Quantum Dots in Solution-Processed White Light-Emitting Diodes

• Published in: Nano letters Vol. 11; no. 2; pp. 329 - 332
• Main Authors: Zhang, Yu, Xie, Chuang, Su, Huaipeng, Liu, Jie, Pickering, Shawn, Wang, Yongqiang, Yu, William W, Wang, Jingkang, Wang, Yiding, Hahm, Jong-in, Dellas, Nicholas, Mohney, Suzanne E, Xu, Jian
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 09-02-2011
• Subjects: Applied sciences; Colloids - chemistry; Cross-disciplinary physics: materials science; rheology; Electronics; Equipment Design; Equipment Failure Analysis; Exact sciences and technology; Lighting - instrumentation; Materials science; Metals, Heavy - chemistry; Molecular electronics, nanoelectronics; Nanocrystalline materials; Nanoscale materials and structures: fabrication and characterization; Nanotechnology - instrumentation; Optoelectronic devices; Physics; Quantum Dots; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Semiconductors; white light-emitting diodes; quantum dots; aging effect; heavy metal-free; Bilayer structure; Zinc sulfide; II-VI semiconductors; Quantum dots; Core shell structure; Light emitting diodes; Optoelectronic devices; Chromaticity; Electroluminescence; Polymers; Nanostructured materials; Bilayers
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl1021442

We report in this communication the design and fabrication of solution-processed white light-emitting diodes (LEDs) containing a bilayer of heavy metal-free colloidal quantum dots (QDs) and polymer in the device active region. White electroluminescence was obtained in the LEDs by mixing the red emission of ZnCuInS/ZnS core/shell QDs and the blue-green emission of poly(N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)benzidine). A high color rendering index of 92 was achieved as compared to a 5310 K blackbody reference by virtue of broadband emission of the QDs. The Commission Internationale de l’Eclairage chromaticity coordinates of the white LED output exhibit a distinctive bias dependence. Finally, aging of the white LEDs was studied, revealing the difference between the photochemical stabilities of the QDs and polymer molecules and the consequent effect on the color evolution of the LEDs.