Structure compensation and illumination uniformity improvement through inkjet printing in organic light-emitting diode subpixels

• Published in: Journal of vacuum science and technology. B, Nanotechnology & microelectronics Vol. 35; no. 2
• Main Authors: Lin, Chin-Yen, Wang, Li-Wen, Liao, Kuan-Hsun, Lo, Cheng-Yao
• Format: Journal Article
• Language: English
• Published: 01.03.2017
• ISSN: 2166-2746; 2166-2754
• DOI: 10.1116/1.4974932

A structural compensation method is proposed and demonstrated for subpixels with global nonuniform surface morphologies in organic light-emitting diodes. The morphologies were realized by identifying the coffee-ring effect in the hole injection layer (HIL) before it was flattened by depositing additional materials into the HIL recess through inkjet printing. The compensated HIL significantly improved the surface and illumination intensity uniformity. Studies of the printing sequence and wetting behaviors of two HILs proved the effectiveness of the proposed approach. Moreover, a scientific quantification method is proposed, through which the authors determined that the surface morphology and illumination intensity distribution of the subpixel improved by 56.3% and 26.2%, respectively. In addition, conductivity and transmittance examinations revealed good continuity between the HILs, indicating that the proposed compensation is efficient and commercially practicable.