Organic light emitting diodes (OLEDs) with slot-die coated functional layers

Abstract

OLEDs have become prominent in commercial display and lighting applications, mainly for television and smartphone screens, and in many electronic gadgets due to superior features over other display technologies such as Liquid Crystal Displays (LCDs). In the evolution of OLED fabrication, roll-to-roll (R2R) solution-based techniques, which are low-cost and high throughput, have emerged as next-generation manufacturing methods for OLED production. Researchers and scientists all over the world are investigating R2R upscaling methods. Thus far, the existing R2R fabrication methods for manufacturing high performance OLEDs have had limited success due to film thickness variations, aggregation in films, challenges in forming the multi-layer structure, and scarcity of efficient interlayers. Slot-die coating is a very promising fabrication technique that can facilitate R2R manufacturing of OLEDs and address some of the aforementioned challenges. In this review, a summary of the developments in OLED fabrication using slot-die coating methods is presented. First, we highlight the research work on the slot-die coating of single and multi-layer OLEDs, and then we present various modifications of slot-die heads to fabricate micro-sized OLEDs for high-resolution display applications. Lastly, we present a qualitative comparison between the performance of OLEDs fabricated by slot-die coating and the ones fabricated by other R2R techniques. While many review articles have been published on OLED materials and devices, there is not one collection of reports detailing the slot-die coating, an additive manufacturing method, of OLEDs.