Investigating the influence of the solution-processing method on the morphological properties of organic semiconductor films and their impact on OLED performance and lifetime

• Published in: Organic electronics Vol. 78; p. 105509
• Main Authors: Hamanaka, Viviane Nogueira, Salsberg, Elizabeth, Fonseca, Fernando Josepetti, Aziz, Hany
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.03.2020
• Subjects: Blade coating; Lifetime; Morphology; OLEDs; Organic semiconductors; Spin coating; Organic semiconductors; Lifetime; OLEDs; Blade coating; Spin coating; Morphology
• ISSN: 1566-1199; 1878-5530
• DOI: 10.1016/j.orgel.2019.105509

The morphological properties of organic semiconductor films deposited by blade coating and spin coating were investigated. The effect of these solution coating methods in fabricating the hole transport layer (HTL) and emissive layer (EML) of OLEDs was also examined. Transient photoluminescence measurements showed that blade-coated films have longer exciton lifetimes than spin-coated films, indicating that blade coating leads to films with less aggregated and more uniform morphologies. OLEDs with a blade-coated CBP:Ir(ppy)3 EML exhibited an external quantum efficiency (EQE) at 20 mA/cm2 of 8.6% versus 6.4% in case of device with the same structure but with a spin-coated EML. Additionally, the blade coated CBP:Ir(ppy)3-based device showed a decrease in electroluminescence emission peak by about 52% from its initial value after 20 min of electrical aging, whereas for the spin-coated device, the decrease was 74%. The higher efficiency and longer lifetime in the blade coated devices is likely a result of a more uniform or less aggregated film morphology. These findings demonstrate that blade coating is a promising solution-based fabrication technique to enable more efficient and longer-lived small molecule, solution-coated OLEDs and organic optoelectronic devices. [Display omitted] •The morphological properties of organic semiconductor films deposited by blade coating and spin coating were investigated.•Blade coating produces films with less aggregated morphologies and higher uniformity relative to spin coating.•OLEDs with blade coated HTLs and EMLs had higher efficiency and longer lifetime than spin-coated ones.