High efficiency AMOLED using hybrid of small molecule and polymer materials patterned by laser transfer

Abstract

Laser-Induced Thermal Imaging (LITI) is a laser addressed patterning process and has unique advantages such as highresolution patterning with over all position accuracy of the imaged stripes of within 2.5 micrometer and scalability to largesize mother glass. This accuracy is accomplished by real-time error correction and a high-resolution stage control system that includes laser interferometers. Here the new concept of hybrid system that complement the merits of small molecule and polymer to be used as an OLED; our system can realize easy processing of light emitting polymers and high luminance efficiency of small molecules. LITI process enables the stripes to be patlerned with excellent thickness uniformity and multistacking of various functional layers without having to use any type of fine metal shadow mask. In this study, we report a full-color hybrid OLED using the multi-layered structure consisting of small molecules and polymers.

Full color organic light emitting diodes with laser-patterned optical path-length compensation layer

“…Hence, there have been a lot of efforts to improve the device performance and finally achieved almost same performances as those obtained from conventional evaporation device. However, it has been continually pointed out that LITI process is very difficult to overcome the particle issue around the active area because the process normally requires continual transfer of glasses and donor films between vacuum and atmospheric pressure condition [14,16,17]. This impurity could be eliminated by CO 2 or laser rinsing process.…”

29.3: A Novel Patterning Method for Full‐Color Organic Light‐Emitting Devices: Laser Induced Thermal Imaging (LITI)

“…Hybrids consisting of small molecules (light-emitting or charge transporting) and LEPs further improve the pattern quality as well as the efficiency and lifetime of LITI devices in comparison to conventional PLED technology [3,4]. The incorporation of the small molecule material lowers the cohesion of the polymer film without greatly reducing the adhesion between the receptor substrate and the hybrid polymer film.…”

“…To overcome this problem, we have developed molecularly doped polymeric systems or small molecule host/LEP blend hybrid systems to reduce cohesion in LITI transfer layers and greatly improve pattern accuracy [3,4]. The small molecule-polymer hybrid mixtures function as an emitting layer in which the small molecules serve as a host system for energy transfer from a fluorescent light-emitting polymer or dispersed phosphorescent dyes.…”

Molecularly doped electrophosphorescent emitters for solution processed and laser patterned devices

“…In that work, we found that the transferring layer fabricated on top of the donor sheets for laser transfer should be a moderate molecular weight material (or a blend of small molecules and polymer), since the transferred layer will not have clear patterns when the cohesive force of the film is too strong, which is typically the case for purely polymeric materials. We obtained excellent pattern image quality and improved device properties using blend systems composed of hole transporting small molecules and a light emitting polymer [13,14].…”